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  Subjects -> BIOLOGY (Total: 2843 journals)
    - BIOCHEMISTRY (214 journals)
    - BIOENGINEERING (93 journals)
    - BIOLOGY (1382 journals)
    - BIOPHYSICS (43 journals)
    - BIOTECHNOLOGY (187 journals)
    - BOTANY (219 journals)
    - CYTOLOGY AND HISTOLOGY (25 journals)
    - ENTOMOLOGY (57 journals)
    - GENETICS (150 journals)
    - MICROBIOLOGY (241 journals)
    - MICROSCOPY (11 journals)
    - ORNITHOLOGY (27 journals)
    - PHYSIOLOGY (66 journals)
    - ZOOLOGY (128 journals)

ZOOLOGY (128 journals)                  1 2     

Acta Herpetologica     Open Access   (Followers: 3)
Acta Theriologica     Full-text available via subscription   (Followers: 6)
Acta Zoologica     Hybrid Journal   (Followers: 3)
Acta Zoologica Cracoviensia     Free   (Followers: 2)
Acta zoológica mexicana     Open Access  
Advances in Zoology     Open Access  
Advances in Zoology and Botany     Open Access  
African Invertebrates     Open Access  
African Journal of Herpetology     Full-text available via subscription   (Followers: 1)
African Zoology     Hybrid Journal   (Followers: 7)
American Journal of Zoological Research     Open Access  
animal     Hybrid Journal   (Followers: 3)
Animal Behaviour     Hybrid Journal   (Followers: 132)
Animal Biology     Hybrid Journal   (Followers: 8)
Animal Biology & Animal Husbandry     Open Access   (Followers: 4)
Animal Biotelemetry     Open Access   (Followers: 2)
Animal Genetics     Hybrid Journal   (Followers: 8)
Animal Migration     Open Access   (Followers: 1)
Animal Studies Journal     Open Access   (Followers: 6)
Annales Zoologici     Full-text available via subscription  
Annales Zoologici Fennici     Open Access  
Annals of Animal Science     Open Access   (Followers: 1)
Annual Review of Animal Biosciences     Full-text available via subscription   (Followers: 4)
Anthrozoos : A Multidisciplinary Journal of The Interactions of People & Animals     Full-text available via subscription   (Followers: 7)
Applied Animal Behaviour Science     Hybrid Journal   (Followers: 14)
Applied Entomology and Zoology     Partially Free   (Followers: 2)
Aquatic Mammals     Full-text available via subscription   (Followers: 3)
Aquatic Sciences     Hybrid Journal   (Followers: 10)
Arthropod Management Tests     Hybrid Journal  
Asian Journal of Animal and Veterinary Advances     Open Access   (Followers: 7)
Australian Journal of Zoology     Hybrid Journal   (Followers: 1)
Bioacoustics : The International Journal of Animal Sound and its Recording     Partially Free   (Followers: 3)
Bird Conservation International     Hybrid Journal   (Followers: 17)
Bird Study     Full-text available via subscription   (Followers: 14)
Brazilian Journal of Veterinary Research and Animal Science     Open Access   (Followers: 7)
British Birds     Full-text available via subscription   (Followers: 7)
Bulletin of the Museum of Comparative Zoology     Full-text available via subscription   (Followers: 4)
Canadian Journal of Animal Science     Full-text available via subscription   (Followers: 5)
Canadian Journal of Zoology     Full-text available via subscription   (Followers: 12)
Contributions to Zoology     Open Access   (Followers: 3)
Der Zoologische Garten     Full-text available via subscription   (Followers: 3)
Ecology of Freshwater Fish     Hybrid Journal   (Followers: 17)
Edentata     Open Access  
European Journal of Taxonomy     Open Access   (Followers: 3)
Euscorpius     Open Access  
EvoDevo     Open Access   (Followers: 1)
Fieldiana Zoology     Full-text available via subscription   (Followers: 2)
Fish and Fisheries     Hybrid Journal   (Followers: 25)
Frontiers in Zoology     Open Access   (Followers: 7)
Graellsia     Open Access  
Hystrix, the Italian Journal of Mammalogy     Open Access  
i-Perception     Open Access   (Followers: 3)
Iheringia. Série Zoologia     Open Access  
In Vitro Cellular & Developmental Biology - Animal     Hybrid Journal   (Followers: 1)
Integrative Zoology     Hybrid Journal  
International Journal of Odonatology     Hybrid Journal   (Followers: 1)
International Journal of Zoological Research     Open Access   (Followers: 2)
International Journal of Zoology     Open Access   (Followers: 2)
International Studies on Sparrows     Open Access  
International Zoo Yearbook     Hybrid Journal   (Followers: 2)
Invertebrate Reproduction & Development     Hybrid Journal   (Followers: 3)
Italian Journal of Animal Science     Open Access   (Followers: 2)
Italian Journal of Zoology     Hybrid Journal   (Followers: 1)
Journal of Agrobiology     Open Access   (Followers: 2)
Journal of Animal Ecology     Hybrid Journal   (Followers: 33)
Journal of Animal Physiology and Animal Nutrition     Hybrid Journal   (Followers: 5)
Journal of Apicultural Science     Open Access   (Followers: 1)
Journal of Applied Animal Research     Hybrid Journal   (Followers: 1)
Journal of Basic & Applied Zoology : Physiology     Open Access  
Journal of Experimental Zoology Part A: Ecological Genetics and Physiology     Hybrid Journal   (Followers: 2)
Journal of Experimental Zoology Part B : Molecular and Developmental Evolution     Hybrid Journal  
Journal of Freshwater Ecology     Hybrid Journal   (Followers: 11)
Journal of Insects     Open Access  
Journal of Venomous Animals and Toxins     Open Access   (Followers: 4)
Journal of Venomous Animals and Toxins including Tropical Diseases     Open Access  
Journal of Wildlife Management     Hybrid Journal   (Followers: 27)
Journal of Zoo and Aquarium Research     Open Access   (Followers: 1)
Journal of Zoological Systematics and Evolutionary Research     Hybrid Journal   (Followers: 5)
Journal of Zoology     Hybrid Journal   (Followers: 9)
Laboratory Animals     Hybrid Journal   (Followers: 10)
Mammalia     Hybrid Journal   (Followers: 7)
Marine Ecology Progress Series MEPS     Hybrid Journal   (Followers: 9)
Mastozoología Neotropical     Open Access  
Memorias de la Conferencia Interna en Medicina y Aprovechamiento de Fauna Silvestre, Exótica y no Convencional     Open Access  
Natural History Sciences     Hybrid Journal  
Neotropical Primates     Open Access  
New Zealand Journal of Zoology     Hybrid Journal  
Papéis Avulsos de Zoologia     Open Access   (Followers: 1)
Parasite     Open Access   (Followers: 6)
Physiological and Biochemical Zoology     Full-text available via subscription   (Followers: 5)
Polish Journal of Entomology     Open Access   (Followers: 2)
Protist Genomics     Open Access   (Followers: 1)
Remote Sensing in Ecology and Conservation     Open Access  
Research in Zoology     Open Access   (Followers: 1)
Revista Brasileira de Zoologia     Open Access  
Revista de Biología Marina y Oceanografía     Open Access   (Followers: 1)
Revista de Zoologia     Open Access   (Followers: 1)
Revista del Museo Argentino de Ciencias Naturales     Open Access  
Russian Journal of Herpetology     Full-text available via subscription   (Followers: 1)
Scientific Journal of Animal Science     Open Access   (Followers: 4)

        1 2     

Journal Cover   Journal of Animal Ecology
  [SJR: 3.074]   [H-I: 102]   [33 followers]  Follow
    
   Hybrid Journal Hybrid journal (It can contain Open Access articles)
   ISSN (Print) 0021-8790 - ISSN (Online) 1365-2656
   Published by John Wiley and Sons Homepage  [1609 journals]
  • Genetic, ecological and geographic covariables explaininghost range and
           specificity of a microsporidian parasite
    • Authors: Benjamin Lange; Andrea Patricia Kaufmann, Dieter Ebert
      Abstract: Parasites often have a smaller geographic distribution than their hosts. Common garden infection trials can untangle the role that historical contingencies, ecological conditions and the genetic constitution of local host populations play in limiting parasite geographic range: however, infection trials usually overestimate the range of hosts in which a parasite could naturally persist. This study overcomes that problem by using multi‐generation, long‐term persistence experiments. We study the microsporidian parasite Hamiltosporidium tvaerminnensis in monoclonal populations of Daphnia magna from 43widely spread sites. The parasite persisted well in hosts collected from its natural geographic range, but demonstrated long‐term persistence in only a few host genotypes outside this range. Genetic distance between hosts from the parasite's origin site and newly tested host populations correlated negatively with parasite persistence. Furthermore, the parasite persisted only in host populations from habitats with a high likelihood of drying up in summer, although we excluded environmental variation in our experiments. Together, our results suggest that host genetic factors play the dominant role in explaining the limited geographic range of parasites, and that these genetic differences covary with geographic distance and the habitat type the host is adapted to. This article is protected by copyright. All rights reserved.
      PubDate: 2015-07-05T21:56:25.452638-05:
      DOI: 10.1111/1365-2656.12421
       
  • Adaptive strategies in nocturnally migrating insects and songbirds:
           contrasting responses to wind
    • Authors: Jason W. Chapman; Cecilia Nilsson, Ka S. Lim, Johan Bäckman, Donald R. Reynolds, Thomas Alerstam
      Abstract: 1. Animals that use flight as their mode of transportation must cope with the fact that their migration and orientation performance is strongly affected by the flow of the medium they are moving in, i.e. by the winds. Different strategies can be used to mitigate the negative effects and benefit from the positive effects of a moving flow. The strategies an animal can use will be constrained by the relationship between the speed of the flow and the speed of the animal's own propulsion in relation to the surrounding air. 2. Here we analyse entomological and ornithological radar data from north‐western Europe to investigate how two different nocturnal migrant taxa, the noctuid moth Autographa gamma and songbirds, deal with wind by analysing variation in resulting flight directions in relation to the wind‐dependent angle between the animal's heading and track direction. 3. Our results, from fixed locations along the migratory journey, reveal different global strategies used by moths and songbirds during their migratory journeys. As expected, nocturnally migrating moths experienced a greater degree of wind drift than nocturnally migrating songbirds, but both groups were more affected by wind in autumn than in spring. 4. The songbirds’ strategies involve elements of both drift and compensation, providing some benefits from wind in combination with destination and time control. In contrast, moths expose themselves to a significantly higher degree of drift in order to obtain strong wind assistance, surpassing the songbirds in mean ground speed, at the cost of a comparatively lower spatiotemporal migratory precision. 5. Moths and songbirds show contrasting but adaptive responses to migrating through a moving flow, which are fine‐tuned to the respective flight capabilities of each group in relation to the wind currents they travel within. This article is protected by copyright. All rights reserved.
      PubDate: 2015-07-04T08:31:09.134657-05:
      DOI: 10.1111/1365-2656.12420
       
  • Quantifying the influence of measured and unmeasured individual
           differences on demography
    • Authors: Floriane Plard; Jean‐Michel Gaillard, Tim Coulson, Daniel Delorme, Claude Warnant, Jacques Michallet, Shripad Tuljapurkar, Siddharth Krishnakumar, Christophe Bonenfant
      Abstract: Demographic rates can vary not only with measured individual characters like age, sex and mass but also with unmeasured individual variables like behaviour, genes and health. Predictions from population models that include measured individual characteristics often differ from models that exclude them. Similarly, unmeasured individual differences have the potential to impact predictions from population models. However, unmeasured individual differences are rarely included in population models. We construct stage‐ and age‐structured models (where stage is mass) of a roe deer population, which are parameterized from statistical functions that either include, or ignore, unmeasured individual differences. We found that mass and age structures substantially impacted model parameters describing population dynamics, as did temporal environmental variation, while unmeasured individual differences impacted parameters describing population dynamics to a much smaller extent once individual heterogeneity related to mass and age has been included in the model. We discuss how our assumptions (unmeasured individual differences only in mean trait values) could have influenced our findings and under what circumstances unmeasured individual differences could have had a larger impact on population dynamics. There are two reasons explaining the relative small influence of unmeasured individual differences on population dynamics in roe deer. First, individual body mass and age both capture a large amount of individual differences in roe deer. Second, in large populations of long‐lived animals, the average quality of individuals (independent of age and mass) within the population is unlikely to show substantial variation over time, unless rapid evolution is occurring. So even though a population consisting of high‐quality individuals would have much higher population growth rate than a population consisting of low‐quality individuals, the probability of observing a population consisting only of high‐quality individuals is small. The authors used a mass‐and‐age structured model of a roe deer population to investigate the influence of unmeasured individual differences on population dynamics. It was found that unmeasured individual differences impacted weakly on parameters describing population dynamics once individual heterogeneity related to mass and age had been included in the model.
      PubDate: 2015-07-03T05:37:42.259506-05:
      DOI: 10.1111/1365-2656.12393
       
  • Colour polymorphism torn apart by opposing positive
           frequency‐dependent selection, yet maintained in space
    • Authors: Swanne P. Gordon; Hanna Kokko, Bibiana Rojas, Ossi Nokelainen, Johanna Mappes
      Abstract: Polymorphic warning signals in aposematic species are enigmatic because predator learning and discrimination should select for the most common coloration, resulting in positive frequency‐dependent survival selection. Here, we investigated whether differential mating success could create sufficiently strong negative frequency‐dependent selection for rare morphs to explain polymorphic (white and yellow) warning coloration in male wood tiger moths (Parasemia plantaginis). We conducted an experiment in semi‐natural conditions where we estimated mating success for both white and yellow male moths under three different morph frequencies. Contrary to expectations, mating success was positively frequency‐dependent: white morph males had high relative fitness when common, likewise yellow morph males had high relative fitness when instead they were common. We hence built a model parameterized with our data to examine whether polymorphism can be maintained despite two sources of positive frequency dependence. The model includes known spatial variation in the survival advantage enjoyed by the yellow morph, and assumes that relative mating success follows our experimentally derived values. It predicts that polymorphism is possible under migration for up to approximately 20% exchange of individuals between subpopulations in each generation. Our results suggest that differential mating success combined with spatial variation in predator communities may operate as a selection mosaic that prevents complete fixation of either morph. This article is protected by copyright. All rights reserved.
      PubDate: 2015-06-26T10:03:19.281835-05:
      DOI: 10.1111/1365-2656.12416
       
  • The developmental race between maturing host plants and their butterfly
           herbivore – the influence of phenological matching and temperature
    • Authors: D. Posledovich; T. Toftegaard, C. Wiklund, J. Ehrlén, K. Gotthard
      Abstract: Interactions between herbivorous insects and their host plants that are limited in time are widespread. Therefore, many insect‐plant interactions result in a developmental race, where herbivores need to complete their development before plants become unsuitable while plants strive to minimize damage from herbivores by outgrowing them. When spring phenologies of interacting species change asymmetrically in response to climate warming there will be a change in the developmental state of host plants at the time of insect herbivore emergence. In combination with altered temperatures during the subsequent developmental period, this is likely to affect interaction strength as well as fitness of interacting species. Here, we experimentally explore if the combined effect of phenological matching and thermal conditions influence the outcome of an insect‐host interaction. We manipulated both developmental stages of the host plants at the start of the interaction and temperature during the subsequent developmental period in a model system of a herbivorous butterfly, Anthocharis cardamines, and five of its Brassicaceae host plant species. Larval performance characteristics were favoured by earlier stages of host plants at oviposition as well as by higher developmental temperatures on most of the host species. The probability of a larva needing a second host plant covered the full range from no influence of either phenological matching or temperature to strong effects of both factors, and complex interactions between them. The probability of a plant outgrowing a larva was dependent only on the species identity. This study demonstrates that climatic variation can influence the outcome of consumer‐resource interactions in multiple ways and that its effects differ among host plant species. Therefore, climate warming is likely to change the temporal match between larval and plant development in some plant species, but not in the others. This is likely to have important implications for host plant use and possibly influence competitive relationships. This article is protected by copyright. All rights reserved.
      PubDate: 2015-06-26T10:02:38.748873-05:
      DOI: 10.1111/1365-2656.12417
       
  • Time‐scale dependency of host plant biomass‐ and
           trait‐mediated indirect effects of deer herbivory on a swallowtail
           butterfly
    • Authors: S. Takagi; T. Miyashita
      Abstract: Despite recent attempts to quantify the relative strength of density‐ and trait‐mediated indirect effects, rarely has the issue been properly addressed at the population level. Most research is based on short‐term small‐scale experiments in which behavioral and/or physiological responses prevail. Here we estimated the time‐scales during which density‐ and trait‐mediated effects manifest, as well as the strength of these effects, using an interaction chain with three organisms (deer‐plant‐butterfly). A hierarchical Bayesian model was performed by using a long‐term dataset of deer density in the Boso Peninsula, central Japan (where local densities differ spatially and temporally) as well as densities of the swallowtail butterfly Byasa alcinous and its host plant Aristolochia kaempferi. The time‐scale effect of deer on plant quantity and quality was estimated according to the degree of carry‐over effects. The negative influence on leaf density showed a temporal saturation pattern over the long term, while the positive influence on leaf quality due to resprouting of leaves after deer browsing, showed no clear temporal trend. The net indirect effect changed from positive to negative with time, with the negative density‐mediated effect becoming prominent in the long‐term. Our novel approach is widely applicable in assessing the dynamic impacts of wildlife if the spatio‐temporal variability of expansion and/or invasion history is known. This article is protected by copyright. All rights reserved.
      PubDate: 2015-06-26T09:55:12.410035-05:
      DOI: 10.1111/1365-2656.12415
       
  • What doesn't kill you might make you stronger: functional basis for
           variation in body armour
    • Authors: Chris Broeckhoven; Genevieve Diedericks, P. le Fras N. Mouton
      Abstract: 1.Predation has been proposed to be a selective agent in the evolution of morphological antipredator strategies in prey. Among vertebrates, one of the morphological traits that evolved multiple times is body armour, including carapaces, thickened keratinised scales and plates of dermal bone. 2.It has been generally assumed that body armour provides protection against a predatory attack, yet, few explicit tests of the hypothesis exist. Cordylidae, a relatively small family of southern African lizards, show considerable variation in the degree of body armour. Hence, this family provides an opportunity to test the hypothesis that body armour serves as protection against predators. 3.Experiments were conducted to test whether the bite forces of four species of mammalian predators were high enough to penetrate the skins of Karusasaurus polyzonus, Namazonurus peersi, Cordylus cordylus and Cordylus macropholis, as well as those of Ouroborus cataphractus individuals originating from three localities that differed in their predator diversity. Furthermore, histological techniques were used to test whether variation in skin toughness was associated with concomitant changes in degree of epidermal (i.e. β‐keratin) and dermal (i.e. osteoderm) armour. 4.The skin toughness values for four out of five cordylid lizards tested in this study were well‐below the bite forces of the mammalian predators. In contrast, the thick osteoderms in the dermis of O. cataphractus can withstand bites from several mongoose species. However, the significant variation in body armour that is present between the three populations of O. cataphractus does not seem to be related to predator diversity. 5.It is concluded that body armour can serve as protection against predation in O. cataphractus, but that alternative selection pressures, such as thermoregulation or predation by snakes, presumably underlie variation in defensive morphology in the other cordylid lizards. This article is protected by copyright. All rights reserved.
      PubDate: 2015-06-22T23:56:52.609705-05:
      DOI: 10.1111/1365-2656.12414
       
  • Testing predator‐prey theory using broad‐scale manipulations
           and independent validation
    • Authors: Robert Serrouya; Bruce N. McLellan, Stan Boutin
      Abstract: 1.A robust test of ecological theory is to gauge the predictive accuracy of general relationships parameterized from multiple systems but applied to a new area. To address this goal, we used an ecosystem‐level experiment to test predator‐prey theory by manipulating prey abundance to determine whether predation was density dependent, density independent, compensatory, or depensatory (inversely density dependent) on prey populations. 2.Understanding the nature of predation is of primary importance in community ecology because it establishes whether predation has little effect on prey abundance (compensatory), whether it promotes coexistence (density dependent), reduces the equilibrium of prey (density independent), or whether it can be destabilizing (depensatory). 3.We used theoretical predictions consisting of functional and numerical equations parameterized independently from meta‐analyses on wolves (Canis lupus) and moose (Alces alces), but applied to our specific wolf‐moose system. Predictions were tested by experimentally reducing moose abundance across 6500 km2 as a novel way of evaluating the nature of predation. 4.Depensatory predation of wolves on moose was the best explanation of the population dynamic – a mechanism that has been hypothesized to occur but has rarely been evaluated. Adding locally obtained kill rates and numerical estimates to the independent data provided no benefit to model predictions, suggesting that the theory was robust to local variation. 5.These findings have critical implications for any organism that is preyed upon but that also has, or will be, subject to increased human exploitation or perturbations from environmental change. If depensatory predation is not accounted for in harvest models, predicted yields will be excessive and lead to further population decline. This article is protected by copyright. All rights reserved.
      PubDate: 2015-06-22T23:36:51.462408-05:
      DOI: 10.1111/1365-2656.12413
       
  • Who escapes detection? Quantifying the causes and consequences of
           sampling biases in a long‐term field study
    • Authors: Lindall R. Kidd; Ben C. Sheldon, Emily G. Simmonds, Ella F. Cole
      Abstract: Inferences drawn from long‐term field studies are vulnerable to biases in observability of different classes of individuals, which may lead to biases in the estimates of selection, or fitness. Population surveys that monitor breeding individuals can introduce such biases by not identifying individuals that fail early in their reproductive attempts. Here, we quantify how the standard protocol for detecting breeding females introduces bias in a long‐term population study of the great tit, Parus major. We do so by identifying females whose breeding attempts fail before they would normally be censused, and explore whether this early failure can be predicted by a number of intrinsic and extrinsic factors. We investigate the effect of these biases on estimates of reproductive performance and selection. We show that females that go undetected by standard censusing because they fail early in their breeding attempt were less likely to have been previously trapped within our study site and were more likely to breed in poor quality habitats. Furthermore we demonstrate that this bias sampling had lead previous studies on this population to overestimate the reproductive performance of unringed females, which are likely to be immigrants to the population. Finally, we show that these biases in detectability influence estimates of selection on a key life history trait. While these conclusions are specific to this study, we suggest that such effects are likely to be widespread, and that more attention should be given to whether or not methods for surveying natural populations introduce systematic bias that will influence conclusions about ecological and evolutionary processes. This article is protected by copyright. All rights reserved.
      PubDate: 2015-06-17T02:23:46.475224-05:
      DOI: 10.1111/1365-2656.12411
       
  • Microhabitat and body size effects on heat tolerance: implications for
           responses to climate change (army ants: Formicidae, Ecitoninae)
    • Authors: Kaitlin M. Baudier; Abigail E. Mudd, Shayna C. Erickson, Sean O'Donnell
      Abstract: Models that predict organismal and population responses to climate change may be improved by considering ecological factors that affect species thermal tolerance. Species differences in microhabitat use can expose animals to diverse thermal selective environments at a given site and may cause sympatric species to evolve different thermal tolerances. We tested the hypothesis that species differences in body size and microhabitat use (above‐ vs. below‐ground activity) would correspond to differences in thermal tolerance (maximum critical temperatures: CTmax). Thermal buffering effects of soil can reduce exposure to extreme high temperatures for below‐ground active species. We predicted larger‐bodied individuals and species would have higher CTmax and that species mean CTmax would covary positively with degree of above‐ground activity. We used Neotropical army ants (Formicidae: Ecitoninae) as models. Army ants vary in microhabitat use from largely subterranean to largely above‐ground active species and are highly size polymorphic. We collected data on above‐ and below‐ground temperatures in habitats used by army ants to test for microhabitat temperature differences, and we conducted CTmax assays for army ant species with varying degrees of surface activity and with different body sizes within and between species. We then tested whether microhabitat use was associated with species differences in CTmax and whether microhabitat was a better predictor of CTmax than body size for species that overlapped in size. Microhabitat use was a highly significant predictor of species' upper thermal tolerance limits, both for raw data and after accounting for the effects of phylogeny. Below‐ground species were more thermally sensitive, with lower maximum critical temperatures (CTmax). The smallest workers within each species were the least heat tolerant, but the magnitude of CTmax change with body size was greater in below‐ground species. Species‐typical microhabitat was a stronger predictor of CTmax than body size for species that overlapped in size. Compared to the soil surface, 10‐cm subsoil was a significantly moderated thermal environment for below‐ground army ants, while maximum surface raid temperatures sometimes exceeded CTmax for the most thermally sensitive army ant castes. We conclude sympatric species differences in thermal physiology correspond to microhabitat use. These patterns should be accounted for in models of species and community responses to thermal variation and climate change. This study assesses the role microhabitat and body size play in setting critical thermal maxima (CTmax) among small‐bodied ectotherms. The authors show that different microhabitat uses among army ants affect CTmax beyond what is explained by size. This challenges the ecological relevance of models for climate change that fail to account for species differences in habitat use.
      PubDate: 2015-06-15T00:01:46.702754-05:
      DOI: 10.1111/1365-2656.12388
       
  • On the variety of methods for calculating confidence intervals by
           bootstrapping
    • Authors: Marie‐Therese Puth; Markus Neuhäuser, Graeme D. Ruxton
      Abstract: Researchers often want to place a confidence interval around estimated parameter values calculated from a sample. This is commonly implemented by bootstrapping. There are several different frequently used bootstrapping methods for this purpose. Here we demonstrate that authors of recent papers frequently do not specify the method they have used and that different methods can produce markedly different confidence intervals for the same sample and parameter estimate. We encourage authors to be more explicit about the method they use (and number of bootstrap resamples used). We recommend the bias corrected and accelerated method as giving generally good performance; although researchers should be warned that coverage of bootstrap confidence intervals is characteristically less than the specified nominal level, and confidence interval evaluation by any method can be unreliable for small samples in some situations. Many scientists use bootstrapping as a method to generate confidence intervals around statistics that they calculate. But several different bootstrapping methods are available. The authors highlight that they can give quite different results, and offer advice on which to chose and how best to implement them.
      PubDate: 2015-06-12T23:45:58.942623-05:
      DOI: 10.1111/1365-2656.12382
       
  • Body size affects individual winter foraging strategies of
           thick‐billed murres in the Bering Sea
    • Authors: Rachael A. Orben; Rosana Paredes, Daniel D. Roby, David B. Irons, Scott A. Shaffer
      Abstract: 1.Foraging and migration often require different energetic and movement strategies. Though not readily apparent, constraints during one phase might influence the foraging strategies observed in another. For marine birds that fly and dive, body size constraints likely present a trade‐off between foraging ability and migration as smaller bodies reduce flight costs whereas larger bodies are advantageous for diving deeper. 2.This study examines individual wintering strategies of deep diving thick‐billed murres (Uria lomvia) breeding at three colonies in the south‐eastern Bering Sea, St Paul, St George, and Bogoslof. These colonies, arranged north to south, are located such that breeding birds forage in a gradient from shelf to deep‐water habitats. 3.We used geolocation time‐depth recorders and stable isotopes from feathers to determine differences in foraging behaviour and diet of murres during three non‐breeding periods, 2008‐11. Body size was quantified by a principal component analysis (wing, culmen, head+bill, and tarsus length). A hierarchical cluster analysis identified winter foraging strategies based on individual movement, diving behaviour, and diet (inferred from stable isotopes). 4.Structural body size differed by breeding island. Larger birds from St Paul had higher wing‐loading than smaller birds from St George. Larger birds, mainly from St Paul, dove to deeper depths, spent more time in the Bering Sea, and likely consumed higher trophic‐level prey in late winter. Three winter foraging strategies were identified. The main strategy, employed by small birds from all three breeding colonies in the first two years, was characterized by high residency areas in the North Pacific south of the Aleutians and nocturnal diving. In contrast, 31% of birds from St Paul remained in the Bering Sea, and foraged mainly during the day, apparently feeding on higher trophic‐level prey. Throat feather stable isotopes indicated that individuals exhibited flexibility in the use of this colony‐specific foraging strategy. The third strategy only occurred in 2010/11, when birds dove more and deeper, suggesting limited prey resources. 5.Foraging strategies partitioned with respect to annual differences, presumably in response to shifts in distribution of prey, and were linked to body size. The presence of a colony specific wintering strategy suggests the potential for overwinter survival differences between these populations. This article is protected by copyright. All rights reserved.
      PubDate: 2015-06-11T03:10:40.65794-05:0
      DOI: 10.1111/1365-2656.12410
       
  • Predictive modelling of habitat selection by marine predators with respect
           to the abundance and depth distribution of pelagic prey
    • Authors: Charlotte Boyd; Ramiro Castillo, George L. Hunt, André E. Punt, Glenn R. VanBlaricom, Henri Weimerskirch, Sophie Bertrand
      Abstract: Understanding the ecological processes that underpin species distribution patterns is a fundamental goal in spatial ecology. However, developing predictive models of habitat use is challenging for species that forage in marine environments, as both predators and prey are often highly mobile and difficult to monitor. Consequently, few studies have developed resource selection functions for marine predators based directly on the abundance and distribution of their prey. We analyse contemporaneous data on the diving locations of two seabird species, the shallow‐diving Peruvian Booby (Sula variegata) and deeper‐diving Guanay Cormorant (Phalacrocorax bougainvilliorum), and the abundance and depth distribution of their main prey, Peruvian anchoveta (Engraulis ringens). Based on this unique dataset, we develop resource selection functions to test the hypothesis that the probability of seabird diving behaviour at a given location is a function of the relative abundance of prey in the upper water column. For both species, we show that the probability of diving behaviour is mostly explained by the distribution of prey at shallow depths. While the probability of diving behaviour increases sharply with prey abundance at relatively low levels of abundance, support for including abundance in addition to the depth distribution of prey is weak, suggesting that prey abundance was not a major factor determining the location of diving behaviour during the study period. The study thus highlights the importance of the depth distribution of prey for two species of seabird with different diving capabilities. The results complement previous research that points towards the importance of oceanographic processes that enhance the accessibility of prey to seabirds. The implications are that locations where prey is predictably found at accessible depths may be more important for surface foragers, such as seabirds, than locations where prey is predictably abundant. Analysis of the relative importance of abundance and accessibility is essential for the design and evaluation of effective management responses to reduced prey availability for seabirds and other top predators in marine systems. This article is protected by copyright. All rights reserved.
      PubDate: 2015-06-09T09:47:12.049722-05:
      DOI: 10.1111/1365-2656.12409
       
  • Habitat‐mediated carry‐over effects lead to context dependent
           outcomes of species interactions
    • Authors: Benjamin G. Van Allen; Volker H.W. Rudolf
      Abstract: When individuals disperse, their performance in newly colonized habitats can be influenced by the conditions they experienced in the past, leading to environmental carry‐over effects. While carry‐over effects are ubiquitous in animal and plant systems, their impact on species interactions and coexistence are largely ignored in traditional coexistence theory. Here we used a combination of modeling and experiments with two competing species to examine when and how such environmental carry‐over effects influence community dynamics and competitive exclusions. We found that variation in the natal habitat quality of colonizing individuals created carry‐over effects which altered competitive coefficients, fecundity and mortality rates, and extinction probabilities of both species. As a consequence, the dynamics of competitive exclusion within and across habitat types was contingent on the natal habitat of colonizing individuals, indicating that spatial carry‐over effects can fundamentally alter the dynamics and outcome of interspecific competition. Interestingly, carry‐over effects persistently influenced dynamics in systems with interspecific competition for the entire duration of the experiment while carry‐over effects were transient and only influenced initial dynamics in single species populations. Thus carry‐over effects can be enhanced by species interactions, suggesting that their long‐term effects may often not be accurately predicted by single species studies. Given that carry‐over effects are ubiquitous in heterogeneous landscapes, our results provide a novel mechanism that could help explain variation in the structure of natural communities. This article is protected by copyright. All rights reserved.
      PubDate: 2015-06-09T09:42:27.646628-05:
      DOI: 10.1111/1365-2656.12408
       
  • Habitat features and long‐distance dispersal modify the use of
           social information by a long‐distance migratory bird
    • Authors: Clark S. Rushing; Michele R. Dudash, Peter P. Marra
      Abstract: 1.The processes by which individuals select breeding sites have important consequences for individual fitness as well as population‐ and community‐dynamics. Although there is increasing evidence that many animal species use information acquired from conspecifics to assess the suitability of potential breeding sites, little is known about how the use of this social information is modified by biotic and abiotic conditions. 2.We used an automated playback experiment to simulate two types of social information, post‐breeding public information and pre‐breeding location cues, to determine the relative importance of these cues for breeding site selection by a migratory songbird, the American redstart (Setophaga ruticilla). In addition, we used stable hydrogen isotopes to determine the dispersal status of individuals that responded to our experimental treatments and quantify whether long‐distance dispersers use different social cues to select breeding sites compared to philopatric individuals. 3.We found that points that received pre‐breeding location cue treatments were significantly more likely to be settled by redstarts than control points that received no playback. However, we found no evidence the redstarts used post‐breeding public information gathered during one season to select breeding sites the following year. Breeding site habitat structure was also a strong predictor of settlement probability, indicating that redstarts modified the use of social information based on habitat cues. Furthermore, stable hydrogen isotope signatures from individuals that responded to location cue treatments suggest that long‐distance dispersers may rely more heavily on these cues than local recruits. 4.Collectively, these results indicate that redstarts use multiple sources of information to select breeding sites, which could buffer individuals from selecting suboptimal sites when they breed in unfamiliar locations or when habitat quality becomes decoupled from social cues. This article is protected by copyright. All rights reserved.
      PubDate: 2015-06-08T05:09:23.236002-05:
      DOI: 10.1111/1365-2656.12395
       
  • Animal personality in a foundation species drives community divergence and
           collapse in the wild
    • Authors: Jonathan N. Pruitt; Andreas P. Modlmeier
      Abstract: 1.Despite thousands of papers on the topic, precious few of the studies on animal personality have considered the role of personality in shaping community‐level processes. Here we test the effect of individual variation on the long‐term trajectories of biological communities, from initiation to their demise. The spider Anelosimus studiosus builds webs that serve as habitat for >50 species of spider, which together construct a species‐rich silken reef. This species also exhibits a temporally consistent behavioral polymorphism where females exhibit either an aggressive or docile phenotype (personality). 2.In this study we established incipient colonies of either two docile or two aggressive females and then tracked community succession and persistence over seven years in the field. In particular we noted the community compositions associated with colony extinction/collapse events, which are common in this species. 3.The community composition of webs founded by different phenotypes diverged rapidly in their early successional stages. However, this period of divergence was ephemeral and all communities eventually converged on a similar composition; communities founded by aggressive females merely took longer to reach it. This secondary stage of community convergence was itself short‐lived and independent of founders’ personality; all communities collapsed within a year of achieving it. 4.Experimentally imposing this fatal climax composition on colonies caused 80% of communities to collapse within a year, suggesting that this climax composition actually causes the collapse of the community. Community collapse was characterized by a complete die‐off of the foundation species and the dispersal of all other spiders. Thus, the behavioral traits of the founding, foundational individuals of these communities dictate their path of succession and longevity in the wild. This article is protected by copyright. All rights reserved.
      PubDate: 2015-06-08T05:08:59.11412-05:0
      DOI: 10.1111/1365-2656.12406
       
  • Implications of scaled δ15N fractionation for community
           predator‐prey body mass ratio estimates in size‐structured
           food webs
    • Authors: J. C. P. Reum; S. Jennings, M. E. Hunsicker
      Abstract: Nitrogen stable isotope ratios (δ15N) may be used to estimate community‐level relationships between trophic level (TL) and body size in size‐structured food webs and hence the mean predator to prey body mass ratio (PPMR). In turn, PPMR is used to estimate mean food chain length, trophic transfer efficiency, rates of change in abundance with body mass (usually reported as slopes of size‐spectra) and to calibrate and validate food web models. When estimating TL, researchers had assumed that fractionation of δ15N (Δδ15N) did not change with TL. However, a recent meta‐analysis indicated that this assumption was not as well supported by data as the assumption that Δδ15N scales negatively with the δ15N of prey. We collated existing fish community δ15N‐body size data for the Northeast Atlantic and tropical Western Arabian Sea, and combined this with new data from the Northeast Pacific. This was used to estimate TL‐body mass relationships and PPMR under constant and scaled Δδ15N assumptions, and to assess how the scaled Δδ15N assumption affects our understanding of the structure of these food webs. Adoption of the scaled Δδ15N approach markedly reduces the previously reported differences in TL at body mass among fish communities from different regions. With scaled Δδ15N, TL‐body mass relationships became more positive and PPMR fell. Results implied that realized prey size choices in these size‐structured fish communities are less variable than previously assumed and food chains potentially longer. The adoption of generic PPMR estimates for calibration and validation of size‐based fish community models is better supported than hitherto assumed, but predicted slopes of community size‐spectra are more sensitive to a given change or error in realized PPMR when PPMR is small. This article is protected by copyright. All rights reserved.
      PubDate: 2015-06-05T05:51:56.890855-05:
      DOI: 10.1111/1365-2656.12405
       
  • Synergistic effects of fire and elephants on arboreal animals in an
           African savannah
    • Authors: Robert M. Pringle; Duncan M. Kimuyu, Ryan L. Sensenig, Todd M. Palmer, Corinna Riginos, Kari E. Veblen, Truman P. Young
      Abstract: Disturbance is a crucial determinant of animal abundance, distribution, and community structure in many ecosystems, but ways in which multiple disturbance types interact remain poorly understood. The effects of multiple‐disturbance interactions can be additive, sub‐additive, or super‐additive (synergistic). Synergistic effects in particular can accelerate ecological change; thus, characterizing such synergies, the conditions under which they arise, and how long they persist has been identified as a major goal of ecology. We factorially manipulated two principal sources of disturbance in African savannahs, fire and elephants, and measured their independent and interactive effects on the numerically dominant vertebrate (the arboreal gekkonid lizard Lygodactylus keniensis) and invertebrate (a guild of symbiotic Acacia ants) animal species in a semi‐arid Kenyan savannah. Elephant exclusion alone (minus fire) had negligible effects on gecko density. Fire alone (minus elephants) had negligible effects on gecko density after 4 months, but increased gecko density two‐fold after 16 months, likely because the decay of fire‐damaged woody biomass created refuges and nest sites for geckos. In the presence of elephants, fire increased gecko density nearly three‐fold within 4 months of the experimental burn: fire increased the incidence of elephant damage to trees, which in turn improved microhabitat quality for geckos. However, this synergistic positive effect of fire and elephants attenuated over the ensuing year, such that only the main effect of fire was evident after 16 months. Fire also altered the structure of symbiotic plant‐ant assemblages occupying the dominant tree species (Acacia drepanolobium); this influenced gecko habitat selection but did not explain the synergistic effect of fire and elephants. However, fire‐driven shifts in plant‐ant occupancy may have indirectly mediated this effect by increasing trees’ susceptibility to elephant damage. Our findings confirm the importance of fire × elephant interactions in structuring arboreal wildlife populations. Where habitat modification by megaherbivores facilitates co‐occurring species, fire may amplify these effects in the short term by increasing the frequency or intensity of herbivory, leading to synergy. In the longer term, tree mortality due to both top‐kill by fire and toppling by large herbivores may reduce overall microhabitat availability, eliminating the synergy. This article is protected by copyright. All rights reserved.
      PubDate: 2015-06-01T10:28:37.535511-05:
      DOI: 10.1111/1365-2656.12404
       
  • When Siberia came to the Netherlands: the response of continental
           black‐tailed godwits to a rare spring weather event
    • Authors: Nathan R. Senner; Mo A. Verhoeven, José M. Abad‐Gómez, Jorge S. Gutiérrez, Jos C. E. W. Hooijmeijer, Rosemarie Kentie, José A. Masero, T. Lee Tibbitts, Theunis Piersma
      Abstract: Extreme weather events have the potential to alter both short‐ and long‐term population dynamics as well as community‐ and ecosystem‐level function. Such events are rare and stochastic, making it difficult to fully document how organisms respond to them and predict the repercussions of similar events in the future. To improve our understanding of the mechanisms by which short‐term events can incur long‐term consequences, we documented the behavioural responses and fitness consequences for a long‐distance migratory bird, the continental black‐tailed godwit Limosa limosa limosa, resulting from a spring snowstorm and three‐week period of record low temperatures. The event caused measurable responses at three spatial scales – continental, regional and local – including migratory delays (+19 days), reverse migrations (>90 km), elevated metabolic costs (+8·8% maintenance metabolic rate) and increased foraging rates (+37%). There were few long‐term fitness consequences, however, and subsequent breeding seasons instead witnessed high levels of reproductive success and little evidence of carry‐over effects. This suggests that populations with continued access to food, behavioural flexibility and time to dissipate the costs of the event can likely withstand the consequences of an extreme weather event. For populations constrained in one of these respects, though, extreme events may entail extreme ecological consequences. This is one of the first studies to document how extreme weather events affect populations at multiple spatial scales, ranging from the local to continental. This enabled the authors to identify how extreme events actually impact individuals and predict what future increases in their occurrence will mean for vulnerable populations.
      PubDate: 2015-05-29T11:23:10.027084-05:
      DOI: 10.1111/1365-2656.12381
       
  • The sign of cascading predator effects varies with prey traits in a
           detrital system
    • Authors: Xinwei Wu; John N. Griffin, Xinqiang Xi, Shucun Sun
      Abstract: 1.Theory and experiments show that the nature of ‘green’ trophic cascades, between predators, herbivores and plants, varies with several key species traits: predator hunting mode and predator‐and‐prey habitat domains. Meanwhile, ‘brown’ cascades between predators, environment‐modifying detritivores and plants have been largely overlooked and the roles of species traits, particularly prey traits, in determining the nature of these cascades remains unclear. 2.We hypothesize that, in predator‐detritivore‐plant interaction chains, the burrowing ability of plant‐facilitating detritivores determines their response to predators and thus the sign of indirect effect transmitted. In the dung‐decomposer food web of an alpine meadow, we predicted that in the presence of aboveground predacious beetles: 1) non‐burrowing detritivores will suffer mortality due to predation and transmit negative indirect effects to plants, whereas 2) burrowing detritivores will escape predation by retreating deeper into the soil, transmitting positive indirect effects to plants. 3.In support of predictions, experiments showed that a single species of predacious beetle: 1) reduced the density of the non‐burrowing species and indirectly reduced dung loss rate, soil nutrient concentrations and plant biomass, but 2) drove the burrowing species deeper, indirectly improved soil conditions and increased plant biomass. 4.These results show that the burrowing ability of a detritivore can determine whether it transmits a negative indirect effect mediated by a reduction in its density, or a positive indirect effect mediated by its behavioral response to predation risk. 5.We call for further tests of our detritivore‐trait hypothesis in different regions and ecosystems to further develop a general trait‐based framework for trophic cascades in detrital food webs. We further advance the general hypothesis that the locomotion traits of prey species (e.g., burrowing/flying ability) may help explain their behavioral response to predation risk and the nature of indirect effect they transmit from predators to plants. This article is protected by copyright. All rights reserved.
      PubDate: 2015-05-23T09:27:03.93-05:00
      DOI: 10.1111/1365-2656.12403
       
  • Ecosystem‐level effects of a globally‐spreading invertebrate
           invader are not moderated by a functionally similar native
    • Authors: Marcin Penk; Kenneth Irvine, Ian Donohue
      Abstract: 1.Biological invasions are a key element of human‐induced global environmental change. However, lack of knowledge of the indirect consequences of invasions, combined with poor understanding of how their ecological effects depend upon competitive attributes of the receiving community, hinders our ability to manage and predict the effects of invasive species on ecosystems. 2.We established an experiment using a combination of both additive and substitutive experimental designs to explore effects of the globally‐spreading mysid shrimp Hemimysis anomala on the biological structure of outdoor pond mecososms in the absence and presence of a functionally similar native competitor, Mysis salemaai. 3.The naturally smaller H. anomala had considerably stronger effects on primary producers, multiple aspects of consumer assemblages and overall biological structure of the ponds in comparison to the functionally similar native. Moreover, the magnitude of these effects was generally independent of the presence of M. salemaai and even total mysid density. H. anomala reduced both the abundance and diversity of zooplankton assemblages significantly, triggering a strong trophic cascade on phytoplankton and a simultaneous increase of benthic invertebrate biomass. These findings indicate that invasion by H. anomala may exacerbate the effects of nutrient enrichment on lakes. 4.Our results demonstrate that introduced species can, irrespective of the presence of functionally similar natives, induce complex changes to ecosystems that reach beyond direct consumptive effects. Moreover, the cascading indirect effects of invasion can exacerbate the impacts of other stressors. Disregarding the complexity of indirect effects therefore risks underestimating significantly the global ecological footprint of biological invasions. This article is protected by copyright. All rights reserved.
      PubDate: 2015-05-23T09:21:39.75134-05:0
      DOI: 10.1111/1365-2656.12402
       
  • Diet complexity in early life affects survival in released pheasants by
           altering foraging efficiency, food choice, handling skills, and gut
           morphology
    • Authors: Mark A. Whiteside; Rufus Sage, Joah R. Madden
      Abstract: Behavioural and physiological deficiencies are major reasons why reintroduction programs suffer from high mortality when captive animals are used. Mitigation of these deficiencies is essential for successful reintroduction programs. Our study manipulated early developmental diet to better replicate foraging behaviour in the wild. Over two years we hand‐reared 1800 pheasants (Phasianus colchicus), from one day old, for seven weeks under different dietary conditions. In year one, 900 pheasants were divided into three groups and reared with (i) commercial chick crumb, (ii) crumb plus 1% live mealworm or (iii) crumb plus 5% mixed seed and fruit. In year two, a further 900 pheasants were divided into two groups and reared with (i) commercial chick crumb or (ii) crumb plus a combination of 1% mealworm and 5% mixed seed and fruit. In both years the commercial chick crumb acted as a control treatment, whilst those with live prey and mixed seeds and fruits mimicking a more naturalistic diet. After seven weeks reared on these diets pheasants were released into the wild. Post release survival was improved with exposure to more naturalistic diets prior to release. We identified four mechanisms to explain this. Pheasants reared with more naturalistic diets: 1) foraged for less time and had a higher likelihood of performing vigilance behaviours; 2) were quicker at handling live prey items; 3) were less reliant on supplementary feed which could be withdrawn; 4) developed different gut morphology. These mechanisms allowed the pheasants to: 1) reduce the risk of predation by reducing exposure time whilst foraging, while allowing more time to be vigilant; 2) be better at handling and discriminating natural food items, and not be solely reliant on supplementary feed; 3) have a better gut system to cope with the natural forage after the cessation of supplementary feeding in the spring. Learning food discrimination, preference and handling skills by the provision of a more naturalistic diet is essential prior to the release of pheasants in a reintroduction program. Subsequent diet, foraging behaviour, gut morphology and digestive capabilities all work together as one nutritional complex. Simple manipulations during early development can influence these characteristics to better prepare an individual for survival upon release. This article is protected by copyright. All rights reserved.
      PubDate: 2015-05-21T02:20:38.113759-05:
      DOI: 10.1111/1365-2656.12401
       
  • Disentangling trait‐based mortality in species with decoupled size
           and age
    • Authors: Shay O'Farrell; Roberto Salguero‐Gómez, Jules M. van Rooij, Peter J. Mumby
      Abstract: 1.Size and age are fundamental organismal traits and, typically, both are good predictors of mortality. For many species, however, size and age predict mortality in ontogenetically opposing directions. Specifically, mortality due to predation is often more intense on smaller individuals whereas mortality due to senescence impacts, by definition, on older individuals. 2.When size‐based and age‐based mortality are independent in this manner, modeling mortality in both traits is often necessary. Classical approaches, such as Leslie or Lefkovitch matrices, usually require the model to infer the state of one trait from the state of the other, for example by assuming that explicitly modelled age (or stage) class structure provides implicit information on underlying size class structure, as is the case in many species. 3.However, the assumption that one trait informs on the other is challenged when size and age are decoupled, as often occurs in invertebrates, fish, reptiles and plants. In these cases, age‐structured models may perform poorly at capturing size‐based mortality, and vice versa. 4.We offer a solution to this dilemma, relaxing the assumption that class structure in one trait is inferable from class structure in another trait. Using empirical data from a reef fish, Sparisoma viride (Scaridae), we demonstrate how an individual‐based model (IBM) can be implemented to model mortality as explicit, independent and simultaneous functions of individual size and age – an approach that mimics the effects of mortality in many wild populations. By validating this ‘multi‐trait IBM’ against three independent lines of empirical data, we determine that the approach produces more convincing predictions of size‐class structure, longevity and post‐settlement mortality for S. viride than do the trait‐independent or single‐trait mortality models tested. 5.Multi‐trait IBMs also allow trait‐based mortality to be modelled either additively or multiplicatively, and individual variability in growth rates can be accommodated. Consequently, we propose that the approach may be useful in fields that may benefit from disentangling, or investigating interactions among, size‐based and age‐based demographic processes, including comparative demography (e.g., life‐history consequences of resource patchiness) and conservation biology (e.g., impacts of invasive predators on size structure but not lifespan of natives). This article is protected by copyright. All rights reserved.
      PubDate: 2015-05-19T05:55:33.975488-05:
      DOI: 10.1111/1365-2656.12399
       
  • Spatial and spatiotemporal variation in metapopulation structure affects
           population dynamics in a passively dispersing arthropod
    • Authors: A De Roissart; S Wang, D Bonte
      Abstract: 1.The spatial and temporal variation in the availability of suitable habitat within metapopulations determines colonization‐extinction events, regulates local population sizes and eventually affects local population and metapopulation stability. Insights into the impact of such a spatiotemporal variation on the local population and metapopulation dynamics are principally derived from classical metapopulation theory and have not been experimentally validated. 2.By manipulating spatial structure in artificial metapopulations of the spider mite Tetranychus urticae, we test to which degree spatial (island‐mainland metapopulations) and spatiotemporal variation (classical metapopulations) in habitat availability affect the dynamics of the metapopulations relative to systems where habitat is constantly available in time and space (patchy metapopulations). 3.Our experiment demonstrates that (i) spatial variation in habitat availability decreases variance in metapopulation size, decreases density dependent dispersal at the metapopulation level, while (ii) spatiotemporal variation in habitat availability increases patch extinction rates, decreases local population and metapopulation sizes, and decreases density dependence in population growth rates. We found dispersal to be negatively density dependent and overall low in the spatial variable mainland‐island metapopulation. 4.This demographic variation subsequently impacts local and regional population dynamics and determines patterns of metapopulation stability. Both local and metapopulation‐level variability is minimised in mainland‐island metapopulations relative to classical and patchy ones. This article is protected by copyright. All rights reserved.
      PubDate: 2015-05-19T05:49:00.784855-05:
      DOI: 10.1111/1365-2656.12400
       
  • Inferring the effects of potential dispersal routes on the metacommunity
           structure of stream insects: as the crow flies, as the fish swims or as
           the fox runs?
    • Authors: Olli‐Matti Kärnä; Mira Grönroos, Harri Antikainen, Jan Hjort, Jari Ilmonen, Lauri Paasivirta, Jani Heino
      Abstract: 1. Metacommunity research relies largely on proxies for inferring the effect of dispersal on local community structure. Overland and watercourse distances have been typically used as such proxies. A good proxy for dispersal should, however, take into account more complex landscape features that can affect an organism's movement and dispersal. The cost distance approach does just that, allowing determining the path of least resistance across a landscape. 2. Here, we examined the distance decay of assemblage similarity within a subarctic stream insect metacommunity. We tested if overland, watercourse and cumulative cost distances performed differently as correlates of dissimilarity in assemblage composition between sites. We also investigated the effect of body size and dispersal mode on metacommunity organisation. 3. We found that dissimilarities in assemblage composition correlated more strongly with environmental than physical distances between sites. Overland and watercourse distances showed similar correlations to assemblage dissimilarity between sites, being sometimes significantly correlated with biological variation of entire insect communities. In metacommunities deconstructed by body size or dispersal mode, contrary to our expectation, passive dispersers showed a slightly stronger correlation than active dispersers to environmental differences between sites, although passive dispersers also showed a stronger correlation than active dispersers to physical distances between sites. The strength of correlation between environmental distance and biological dissimilarity also varied slightly among the body size classes. 4. After controlling for environmental differences between sites, cumulative cost distances were slightly better correlates of biological dissimilarities than overland or watercourse distances between sites. However, quantitative differences in correlation coefficients were small between different physical distances. 5. Although environmental differences typically override physical distances as determinants of the composition of stream insect assemblages, correlations between environmental distances and biological dissimilarities are typically rather weak. This undetermined variation may be attributable to dispersal processes, which may be captured using better proxies for the process. We suggest that further modifying the measurement of cost distances may be a fruitful avenue, especially if complemented by more direct natural history information on insect dispersal behaviour and distances travelled by them. This article is protected by copyright. All rights reserved.
      PubDate: 2015-05-18T04:04:20.700177-05:
      DOI: 10.1111/1365-2656.12397
       
  • The role of a dominant predator in shaping biodiversity over space and
           time in a marine ecosystem
    • Authors: Kari E. Ellingsen; Marti J. Anderson, Nancy L. Shackell, Torkild Tveraa, Nigel G. Yoccoz, Kenneth T. Frank
      Abstract: Exploitation of living marine resources has resulted in major changes to populations of targeted species and functional groups of large‐bodied species in the ocean. However, the effects of over‐fishing and collapse of large top predators on the broad‐scale biodiversity of oceanic ecosystems remains largely unexplored. Populations of the Atlantic cod (Gadus morhua) were overfished and several collapsed in the early 1990s across Atlantic Canada, providing a unique opportunity to study potential ecosystem‐level effects of the reduction of a dominant predator on fish biodiversity, and to identify how such effects might interact with other environmental factors, such as changes in climate, over time. We combined causal modelling with model selection and multi‐model inference to analyse 41 years of fishery‐independent survey data (1970‐2010) and quantify ecosystem‐level effects of over‐fishing and climate variation on the biodiversity of fishes across a broad area (172,000 km2) of the Scotian Shelf. We found that alpha and beta diversity increased with decreases in cod occurrence; fish communities were less homogeneous and more variable in systems where cod no longer dominated. These effects were most pronounced in the colder north‐eastern parts of the Scotian Shelf. Our results provide strong evidence that intensive harvesting (and collapse) of marine apex predators can have large impacts on biodiversity, with far‐reaching consequences for ecological stability across an entire ecosystem. This article is protected by copyright. All rights reserved.
      PubDate: 2015-05-18T04:03:18.416362-05:
      DOI: 10.1111/1365-2656.12396
       
  • Movement is the glue connecting home ranges and habitat selection
    • Authors: Bram Van Moorter; Christer M. Rolandsen, Mathieu Basille, Jean‐Michel Gaillard
      Abstract: 1.Animal space use has been studied by focusing either on geographic (e.g., home ranges, species’ distribution) or environmental (e.g., habitat use and selection) space. However, all patterns of space use emerge from individual movements, which are the primary means by which animals change their environment. 2.Individuals increase their use of a given area by adjusting two key movement components: the duration of their visit, and/or the frequency of re‐visits. Thus, in spatially heterogeneous environments animals exploit known, high‐quality resource areas by increasing their Residence Time (RT) in and/or decreasing their Time to Return (TtoR) to these areas. We expected that spatial variation in these two movement properties should lead to observed patterns of space use in both geographic and environmental spaces. We derived a set of 9 predictions linking spatial distribution of movement properties to emerging space use patterns. We predicted that, at a given scale, high variation in RT and TtoR among habitats leads to strong habitat selection, and that long RT and short TtoR result in a small home range size. 3.We tested these predictions using moose (Alces alces) GPS tracking data. We first modelled the relationship between landscape characteristics and movement properties. Then, we investigated how the spatial distribution of predicted movement properties (i.e., spatial autocorrelation, mean, and variance of RT and TtoR) influences home range size and hierarchical habitat selection. 4.In landscapes with high spatial autocorrelation of RT and TtoR, a high variation in both RT and TtoR occurred in home ranges. As expected, home range location was highly selective in such landscapes (i.e., 2nd‐order habitat selection); RT was higher and TtoR lower within the selected home range than outside, and moose home ranges were small. Within home ranges, a higher variation in both RT and TtoR was associated to higher selectivity among habitat types (i.e., 3rd‐order habitat selection). 5.Our findings show how patterns of geographic and environmental space use correspond to the two sides of a coin, linked by movement responses of individuals to environmental heterogeneity. By demonstrating the potential to assess the consequences of altering RT or TtoR (e.g., through human disturbance or climatic changes) on home range size and habitat selection, our work sets the basis for new theoretical and methodological advances in movement ecology. This article is protected by copyright. All rights reserved.
      PubDate: 2015-05-16T00:15:47.35042-05:0
      DOI: 10.1111/1365-2656.12394
       
  • Spatial distribution of fishes in a Northwest Atlantic ecosystem in
           relation to risk of predation by a marine mammal
    • Authors: Douglas P. Swain; Hugues P. Benoît, Mike O. Hammill
      Abstract: 1.Numerous studies have shown that, at spatial scales of meters to several kilometers, animals balance the trade‐off between foraging success and predation mortality by increasing their use of safer but less profitable habitats as predation risk increases. However, it is less clear whether prey respond similarly at the larger spatiotemporal scales of many ecosystems. 2.We determine whether this behaviour is evident in a large marine ecosystem, the southern Gulf of St. Lawrence (sGSL, 75,000 km2) over a 42‐year period. This ecosystem is characterized by a recent increase in the abundance of a large marine predator, the grey seal (Halichoerus grypus Fabricius), by more than an order of magnitude. 3.We compared changes in spatial distribution over the 1971‐2012 period between important prey of grey seals (Atlantic cod, Gadus morhua L.; white hake, Urophycis tenuis Mitchill; and thorny skate, Amblyraja radiata Donovan) and non‐prey fishes. Distribution was modelled using Generalized Additive Models incorporating spatially‐variable effects of predation risk, density dependence and water temperature. 4.Distributions of cod, hake and skate were strongly related to risk of predation by seals, with distribution shifting into lower risk areas as predation risk increased. Non‐prey species did not show similar changes in habitat use. Spatial variation in fish condition suggests that these low risk areas are also less profitable for cod and skate in terms of food availability. The effects of density‐dependence and water temperature were also important in models, but did not account for the changes in habitat use as risk of predation increased. 5.These results indicate that these fish are able to assess and respond to spatial variation in predation risk at very large spatial scales. They also suggest that non‐consumptive “risk” effects may be an important component of the declines in productivity of seal prey in this ecosystem, and of the indirect effects at lower trophic levels. This article is protected by copyright. All rights reserved.
      PubDate: 2015-05-14T08:52:49.322374-05:
      DOI: 10.1111/1365-2656.12391
       
  • Population density and climate shape early‐life survival and
           recruitment in a long‐lived pelagic seabird
    • Authors: R Fay; H Weimerskirch, K Delord, C Barbraud
      Abstract: 1. Our understanding of demographic processes is mainly based on analyses of traits from the adult component of populations. Early‐life demographic traits are poorly known mainly for methodological reasons. Yet, survival of juvenile and immature individuals is critical for the recruitment into the population and thus for the whole population dynamic, especially for long‐lived species. This bias currently restrains our ability to fully understand population dynamic of long‐lived species and life history theory. 2. The goal of this study was to estimate the early‐life demographic parameters of a long‐lived species with a long immature period (9‐10 years), to test for sex and age effects on these parameters, and to identify the environmental factors encountered during the period of immaturity that may influence survival and recruitment. 3. Using capture‐mark‐recapture multi‐event models allowing us to deal with uncertain and unobservable individual states, we analysed a long‐term data set of wandering albatrosses to estimate both age and sex specific early‐life survival and recruitment. We investigated environmental factors potentially driving these demographic traits using climatic and fisheries covariates and tested for density dependence. 4. Our study provides for the first time an estimate of annual survival during the first two years at sea for an albatross species (0.801±0.014). Both age and sex affected early‐life survival and recruitment processes of this long‐lived seabird species. Early‐life survival and recruitment were highly variable across years although the sensitivity of young birds to environmental variability decreased with age. Early‐life survival was negatively associated with sea surface temperature and recruitment rate was positively related to both Southern Annular Mode and sea surface temperature. We found strong evidence for density dependence mortality of juveniles. Population size explained 41% of the variation of this parameter over the study period. 5. These results indicate that early‐life survival and recruitment were strongly age and sex‐dependent in a dimorphic long‐lived species. In addition, early life demographic parameters were affected by natal environmental conditions and by environmental conditions faced during the period of immaturity. Finally, our results constitute one of the first demonstrations of density dependence on juvenile survival in seabirds, with major consequences for our understanding of population dynamics in seabirds. This article is protected by copyright. All rights reserved.
      PubDate: 2015-05-14T08:51:53.564576-05:
      DOI: 10.1111/1365-2656.12390
       
  • Double decomposition: decomposing the variance in subcomponents of male
           extra‐pair reproductive success
    • Authors: Sylvain Losdat; Peter Arcese, Jane M. Reid
      Abstract: 1.Extra‐pair reproductive success (EPRS) is a key component of male fitness in socially monogamous systems, and could cause selection on female extra‐pair reproduction if extra‐pair offspring (EPO) inherit high value for EPRS from their successful extra‐pair fathers. However, EPRS is itself a composite trait that can be fully decomposed into subcomponents of variation, each of which can be further decomposed into genetic and environmental variances. However, such decompositions have not been implemented in wild populations, impeding evolutionary inference. 2.We first show that EPRS can be decomposed into the product of three life‐history subcomponents: the number of broods available to a focal male to sire EPO, the male's probability of siring an EPO in an available brood, and the number of offspring in available broods. This decomposition of EPRS facilitates estimation from field data because all subcomponents can be quantified from paternity data without need to quantify extra‐pair matings. Our decomposition also highlights that the number of available broods, and hence population structure and demography, might contribute substantially to variance in male EPRS and fitness. 3.We then used 20 years of complete genetic paternity and pedigree data from wild song sparrows (Melospiza melodia) to partition variance in each of the three subcomponents of EPRS, and thereby estimate their additive genetic variance and heritability conditioned on effects of male coefficient of inbreeding, age and social status. 4.All three subcomponents of EPRS showed some degree of within‐male repeatability, reflecting combined permanent environmental and genetic effects. Number of available broods and offspring per brood showed low additive genetic variances. The estimated additive genetic variance in extra‐pair siring probability was larger, although the 95% credible interval still converged towards zero. Siring probability also showed inbreeding depression and increased with male age, while the numbers of available broods and offspring per brood did not. 5.Our results indicate that the probability that a male will sire an extra‐pair offspring in an available brood is the primary source of genetic variation in male EPRS, implying that the evolution of female extra‐pair reproduction could be facilitated by genetic covariance with this subcomponent of EPRS. This article is protected by copyright. All rights reserved.
      PubDate: 2015-05-14T08:41:15.056339-05:
      DOI: 10.1111/1365-2656.12389
       
  • Exploiting the richest patch has a fitness pay‐off for the migratory
           swift parrot
    • Authors: Dejan Stojanovic; Aleks Terauds, Martin J. Westgate, Matthew H. Webb, David A. Roshier, Robert Heinsohn
      Abstract: Unlike philopatric migrants, the ecology of nomadic migrants is less well understood. This life‐history strategy reflects responses to spatiotemporal variation in resource availability and the need to find resource rich patches to initiate breeding. The fitness consequences of movements between regions of patchily distributed resources can provide insight into ecology of all migrants and their responses to global change. We link broad‐scale data on spatiotemporal fluctuation in food availability to data on settlement patterns and fitness outcomes for a nomadic migrant, the endangered swift parrot Lathamus discolor. We test several predictions to determine whether facultative movements are adaptive for individual swift parrots in an environment where resources are patchily distributed over time and space. Variation in the availability of swift parrot food resources across our study period was dramatic. As a consequence, swift parrots moved to breed wherever food was most abundant and did not resettle nesting regions in successive years when food availability declined. By moving, swift parrots exploited a variable food resource and reproduced successfully. Exploiting the richest patches allowed swift parrots to maintain stable fitness outcomes between discrete breeding events at different locations. Unlike sedentary species that often produce few or lower quality offspring when food is scarce, nomadic migration buffered swift parrots against extreme environmental variation. We provide the first detailed evidence that facultative movements and nomadic migration are adaptive for individuals in unpredictable environments. Our data support the widely held assumption that nomadic migration allows animals to escape resource limitation. Exploiting the richest patch allowed swift parrots to maintain stable reproductive outcomes irrespective of the particular location where they bred. Unlike sedentary species that often produce few or lower quality offspring when food is scarce, nomadic migration buffered swift parrots against extreme environmental variation.
      PubDate: 2015-05-14T00:58:13.324726-05:
      DOI: 10.1111/1365-2656.12375
       
  • Age‐related effects of chronic hantavirus infection on female host
           fecundity
    • Authors: Eva R. Kallio; Heikki Helle, Esa Koskela, Tapio Mappes, Olli Vapalahti
      Abstract: 1.Pathogens often cause detrimental effects to their hosts and, consequently, may influence host population dynamics that may, in turn, feed back to pathogen transmission dynamics. Understanding fitness effects of pathogens upon animal host populations can help to predict the risks that zoonotic pathogens pose to humans. 2.Here we determine whether chronic infection by Puumala hantavirus (PUUV) affects important fitness related traits, namely the probability of breeding, reproductive effort and mother and offspring condition, in the bank vole (Myodes glareolus). Using nine years empirical data in a PUUV endemic area in Central Finland, we found differences between reproductive characteristics of PUUV‐infected and uninfected female bank voles. 3.Young infected females had a significantly higher, and old individuals lower, likelihood of reproducing than uninfected animals during the middle of the breeding season. The implication is that PUUV infection may have long‐term deleterious effects that are observed at old age, while in young individuals the infection may enhance breeding probability by directing resources towards current breeding. 4.Moreover, PUUV infection was related with the mother's body condition. Infected mothers were in poorer condition than uninfected mothers in the early breeding season, but were in better condition than uninfected mothers during the middle of the breeding season. Offspring body condition was positively associated with mother's body condition, which, in turn, was related to the PUUV infection status of the mother. 5.Our findings indicate that chronic infection may affect the reproduction of female hosts, but the effect is dependent on the host age. The effect of chronic hantavirus infection was small and density‐independent and hence unlikely to contribute to the cyclic population dynamics of the host. However, the effects on a female's reproductive output might affect the abundance of young susceptible individuals in the population and hence influence the transmission and persistence of the pathogen. Although experimental and long‐term capture‐mark‐recapture studies are required to further clarify the fitness effects of hantavirus infection and their consequences for pathogen dynamics, this study shows that the infection may have complex effects that are dependent on the age of the individual and the time of the breeding season. This article is protected by copyright. All rights reserved.
      PubDate: 2015-05-12T10:17:17.430852-05:
      DOI: 10.1111/1365-2656.12387
       
  • Predicting the continuum between corridors and barriers to animal
           movements using Step Selection Functions and Randomized Shortest Paths
    • Authors: Manuela Panzacchi; Bram Van Moorter, Olav Strand, Marco Saerens, Ilkka Kivimäki, Colleen Cassady St.Clair, Ivar Herfindal, Luigi Boitani
      Abstract: 1.The loss, fragmentation, and degradation of habitat everywhere on Earth prompt increasing attention to identifying landscape features that support animal movement (corridors) or impede it (barriers). Most algorithms used to predict corridors assume that animals move through preferred habitat either optimally (e.g. Least Cost Path), or as random‐walkers (e.g. Current Models), but neither extreme is realistic. 2.We propose that corridors and barriers are two sides of the same coin, and that animals experience landscapes as spatio‐temporally dynamic corridor‐barrier continua connecting (separating) functional areas where individuals fulfill specific ecological processes. Based on this conceptual framework, we propose a novel methodological approach that uses high‐resolution individual‐based movement data to predict corridor‐barrier continua with increased realism. 3.Our approach consists of two innovations. First, we use Step Selection Functions (SSF) to predict friction maps quantifying corridor‐barrier continua for tactical steps between consecutive locations. Second, we introduce to movement ecology the Randomized Shortest Path algorithm (RSP) which operates on friction maps to predict the corridor‐barrier continuum for strategic movements between functional areas. By modulating the parameter Ѳ, which controls the trade‐off between exploration and optimal exploitation of the environment, RSP bridges the gap between algorithms assuming optimal movements (when Ѳ approaches infinity, RSP is equivalent to LCP) or random‐walk (when Ѳ → 0, RSP → Current Models). 4.Using this approach, we identify migration corridors for GPS‐monitored wild reindeer (Rangifer t. tarandus) in Norway. We demonstrate that reindeer movement is best predicted by an intermediate value of Ѳ, indicative of a movement trade‐off between optimization and exploration. Model calibration allows identification of a corridor‐barrier continuum that closely fits empirical data, and demonstrates that RSP outperforms models that assume either optimality or random‐walk. 5.The proposed approach models the multi‐scale cognitive maps by which animals likely navigate real landscapes, and generalizes the most common algorithms for identifying corridors. Because sub‐optimal, but non‐random, movement strategies are likely widespread, our approach has the potential to predict more realistic corridor‐barrier continua for a wide range of species. This article is protected by copyright. All rights reserved.
      PubDate: 2015-05-07T03:56:33.585073-05:
      DOI: 10.1111/1365-2656.12386
       
  • Seasonal Demography of a Cyclic Lemming Population in the Canadian Arctic
    • Authors: Dominique Fauteux; Gilles Gauthier, Dominique Berteaux
      Abstract: 1.The causes of cyclical fluctuations in animal populations remain a controversial topic in ecology. Food limitation and predation are two leading hypotheses to explain small mammal population dynamics in northern environments. We documented the seasonal timing of the decline phases and demographic parameters (survival and reproduction) associated with population changes in lemmings, allowing us to evaluate some predictions from these two hypotheses. 2.We studied the demography of brown lemmings (Lemmus trimucronatus), a species showing 3‐4 year population cycles in the Canadian Arctic, by combining capture‐mark‐recapture analysis of summer live‐trapping with monitoring of winter nests over a 10‐year period. We also examined the effects of some weather variables on survival. 3.We found that population declines after a peak occurred between the summer and winter period and not during the winter. During the summer, population growth was driven by change in survival, but not in fecundity or proportion of juveniles, whereas in winter population growth was driven by changes in late summer and winter reproduction. 4.We did not find evidence for direct density‐dependence on summer demographic parameters, though our analysis was constrained by the paucity of data during the low phase. Body mass, however, was highest in peak years. 5.Weather effects were detected only in early summer when lemming survival was positively related to snow depth at the onset of melt but negatively related to rainfall. 6.Our results show that high mortality causes population declines of lemmings during summer and fall, which suggests that predation is sufficient to cause population crashes, whereas high winter fecundity is the primary factor leading to population irruptions. The positive association between snow depth and early summer survival may be due to the protective cover offered by snow against predators. It is still unclear why reproduction remains low during the low phase. This article is protected by copyright. All rights reserved.
      PubDate: 2015-05-05T02:16:32.001481-05:
      DOI: 10.1111/1365-2656.12385
       
  • Greater flexibility in metabolic rate confers a growth advantage under
           changing food availability
    • Authors: Sonya K. Auer; Karine Salin, Agata M. Rudolf, Graeme J. Anderson, Neil B. Metcalfe
      Abstract: 1.Phenotypic flexibility in physiological, morphological, and behavioural traits can allow organisms to cope with environmental challenges. Given recent climate change and the degree of habitat modification currently experienced by many organisms, it is therefore critical to quantify the degree of phenotypic variation present within populations, individual capacities to change, and what their consequences are for fitness. 2.Flexibility in standard metabolic rate (SMR) may be particularly important since SMR reflects the minimal energetic cost of living and is one of the primary traits underlying organismal performance. SMR can increase or decrease in response to food availability, but the consequences of these changes for growth rates and other fitness components are not well known. 3.We examined individual variation in metabolic flexibility in response to changing food levels and its consequences for somatic growth in juvenile brown trout (Salmo trutta). 4.SMR increased when individuals were switched to a high food ration and decreased when they were switched to a low food regime. These shifts in SMR, in turn, were linked with individual differences in somatic growth; those individuals that increased their SMR more in response to elevated food levels grew fastest, while growth at the low food level was fastest in those individuals that depressed their SMR most. 5.Flexibility in energy metabolism is therefore a key mechanism to maximize growth rates under the challenges imposed by variability in food availability and is likely to be an important determinant of species’ resilience in the face of global change. This article is protected by copyright. All rights reserved.
      PubDate: 2015-05-05T02:08:03.743865-05:
      DOI: 10.1111/1365-2656.12384
       
  • Digestive capacity predicts diet diversity in Neotropical frugivorous bats
    • Authors: Romeo A. Saldaña‐Vázquez; Eduardo Ruiz‐Sanchez, Leonel Herrera‐Alsina, Jorge E. Schondube
      Abstract: 1.Predicting the diet diversity of animals is important to basic and applied ecology. Knowledge of diet diversity in animals helps us understand niche partitioning, functional diversity and ecosystem services such as pollination, pest control and seed dispersal. 2.There is a negative relationship between the length of the digestive tract and diet diversity in animals; however the role of digestive physiology in determining diet diversity has been ignored. This is especially important in vertebrates with powered flight because, unlike non‐flying vertebrates, they have limitations that may constrain gut size. 3.Here we evaluate the relationship between digestive capacity and diet diversity in Carollinae and Stenodermatinae frugivorous bats. These bats disperse the seeds of plants that are key to Neotropical forest regeneration. 4.Our results show that digestive capacity is a good predictor of diet diversity in Carollinae and Stenodermatinae frugivorous bats (R2 = 0.77). 5.Surprisingly, the most phylogenetically closely related species were not similar in their digestive capacity or diet diversity. The lack of a phylogenetic signal for the traits evaluated implies differences in digestive physiology and diet in closely related species. 6.Our results highlight the predictive usefulness of digestive physiology for understanding the feeding ecology of animals. This article is protected by copyright. All rights reserved.
      PubDate: 2015-04-28T07:14:26.855774-05:
      DOI: 10.1111/1365-2656.12383
       
  • What is the animal doing' Tools for exploring behavioral structure in
           animal movements
    • Authors: Eliezer Gurarie; Chloe Bracis, Maria Delgado, Trevor D. Meckley, Ilpo Kojola, C. Michael Wagner
      Abstract: 1.Movement data provide a window ‐ often our only window ‐ into the cognitive, social and biological processes that underlie the behavioral ecology of animals in the wild. Robust methods for identifying and interpreting distinct modes of movement behavior are of great importance, but complicated by the fact that movement data are complex, multivariate, and dependent. Many different approaches to exploratory analysis of movement have been developed to answer similar questions and practitioners are often at a loss for how to choose an appropriate tool for a specific question. 2.We apply and compare four methodological approaches: first passage time (FPT), Bayesian partitioning of Markov models (BPMM), behavioral change point analysis (BCPA), and a fitted multi‐state random walk (MRW) to three simulated tracks and two animal trajectories ‐ a sea lamprey (Petromyzon marinus) tracked for 12 hours and a wolf (Canis lupus) tracked for one year. 3.The simulations ‐ in which, respectively, velocity, tortuosity, and spatial bias change ‐ highlight the sensitivity of all methods to model misspecification. Methods that do not account for autocorrelation in the movement variables lead to spurious change points while methods that do not account for spatial bias completely miss changes in orientation. We make suggestions towards unifying directions for methodological advances. 4.When applied to the animal data, the methods broadly agree on the structure of the movement behaviors. Important discrepancies, however, reect differences in the assumptions and nature of the outputs. Important trade‐offs are between the strength of the a priori assumptions (low in BCPA, high in MRW), complexity of output (high in the BCPA, low in the BPMM and MRW), and explanatory potential (highest in the MRW). 5.The animal track analysis suggests some general principles for the exploratory analysis of movement data, including ways to exploit the strengths of the various methods. We argue for close and detailed exploratory analysis of movement before fitting complex movement models. This article is protected by copyright. All rights reserved.
      PubDate: 2015-04-23T09:48:38.045866-05:
      DOI: 10.1111/1365-2656.12379
       
  • Social information from immigrants: multiple immigrant based sources of
           information for dispersal decisions in a ciliate
    • Authors: Staffan Jacob; Alexis S. Chaine, Nicolas Schtickzelle, Michèle Huet, Jean Clobert
      Abstract: Dispersal is increasingly recognized as being an informed process, based on information organisms obtain about the landscape. While local conditions are often found to drive dispersal decisions, local context is not always a reliable predictor of conditions in neighbouring patches, making the use of local information potentially useless or even maladaptive. In this case, using social information gathered by immigrants might allow adjusting dispersal decisions without paying the costs of prospecting. However, this hypothesis has been largely neglected despite its major importance for ecological and evolutionary processes. We investigated three fundamental questions about immigrant informed dispersal: do immigrants convey information that influences dispersal, do organisms use multiple cues from immigrants, and is immigrant informed dispersal genotype‐dependent' Using Tetrahymena thermophila ciliates in microcosms, we manipulated the number of immigrants arriving, the density of congeners and resource quality in neighbouring patches, matrix characteristics and the level of cooperation of individuals in the neighbouring populations. We provide the first experimental evidence that immigrants convey a number of different cues about neighbouring patches and matrix (patch quality, matrix characteristics, and cooperation in neighbouring populations) in this relatively simple organism. Furthermore, we demonstrate genotype‐dependent immigrant‐informed dispersal decisions about patch quality and matrix characteristics. Multiple cues from immigrants and genotype‐dependent use of cues have major implications for theoretical metapopulation dynamics and the potential for local adaptation. This article is protected by copyright. All rights reserved.
      PubDate: 2015-04-22T20:46:08.042846-05:
      DOI: 10.1111/1365-2656.12380
       
  • Disentangling direct and growth‐mediated influences on early
           survival: a mechanistic approach
    • Authors: Floriane Plard; Nigel G. Yoccoz, Christophe Bonenfant, François Klein, Claude Warnant, Jean‐Michel Gaillard
      Abstract: 1.Early survival is a key life‐history trait that often accounts for a large part of the variation in individual fitness and shapes population dynamics. The factors influencing early survival are multiple in large herbivores, including malnutrition, predation, cohort variation or maternal effects. However, the mechanistic pathways connecting these drivers to variation in early survival are much less studied. Indeed, whether these factors influence early survival directly or indirectly through early growth remains to be disentangled. 2.In this study, we used a path analysis to separate the direct and indirect (i.e. mediated by early growth) pathways through which sex, birth date, cohort and family effects influence early survival. We used a large dataset of marked roe deer newborns collected from 1985 to 2010 in the intensively monitored population of Trois Fontaines (France). 3.We found that most drivers have indirect influences on early survival through early growth. Indeed, cohort effects influenced early survival through the indirect effect of precipitation around birth on early growth during the birth period. Precipitation also had direct effects on early survival. Family effects indirectly influenced early survival. Twins from the same litter grew at about the same rate, so they had the same fate. Moreover, some factors, such as birth date, had both direct and indirect effects on roe deer early survival, with fawns born early in the season benefiting from high early survival both because they have more time to grow before the harsh season and because they grow faster during their first days of life than late‐born fawns. 4.These findings suggest that most drivers of early survival previously identified in large mammalian herbivores may affect early survival primarily through their influence on early growth. Disentangling the direct and indirect pathways by which different factors influence early survival is of crucial importance to understand the mechanisms shaping this key component of individual fitness. This article is protected by copyright. All rights reserved.
      PubDate: 2015-04-17T01:20:54.66407-05:0
      DOI: 10.1111/1365-2656.12378
       
  • Migration timing and its determinants for nocturnal migratory birds during
           autumn migration
    • Authors: Frank A. La Sorte; Wesley H. Hochachka, Andrew Farnsworth, Daniel Sheldon, Daniel Fink, Jeffrey Geevarghese, Kevin Winner, Benjamin M. Van Doren, Steve Kelling
      Abstract: 1.Migration is a common strategy used by birds that breed in seasonal environments, and multiple environmental and biological factors determine the timing of migration. How these factors operate in combination during autumn migration, which is considered to be under weaker time constraints relative to spring migration, is not clear. 2.Here, we examine the patterns and determinants of migration timing for nocturnal migrants during autumn migration in the northeastern USA using nocturnal reflectivity data from 12 weather surveillance radar stations and modeled diurnal probability of occurrence for 142 species of nocturnal migrants. We first model the capacity of seasonal atmospheric conditions (wind and precipitation) and ecological productivity (vegetation greenness) to predict autumn migration intensity. We then test predictions, formulated under optimal migration theory, on how migration timing should be related to assemblage‐level estimates of body size and total migration distance within the context of dietary guild (insectivore and omnivore) and level of dietary plasticity during autumn migration. 3.Our results indicate seasonal declines in ecological productivity delineate the beginning and end of peak migration, whose intensity is best predicted by the velocity of winds at migration altitudes. Insectivorous migrants departed earlier in the season and, consistent with our predictions, large‐bodied and long‐distance insectivorous migrants departed the earliest. Contrary to our predictions, large‐bodied and some long‐distance omnivorous migrants departed later in the season, patterns that were replicated in part by insectivorous migrants that displayed dietary plasticity during autumn migration. 4.Our findings indicate migration timing in the region is dictated by optimality strategies, modified based on the breadth and flexibility of migrant's foraging diets, with declining ecological productivity defining possible resource thresholds during which migration occurs when winds at migration altitudes are mild. These observations provide the basis to assess how avian migration strategies may be affected by adjustments in seasonal patterns of atmospheric circulation and ecological productivity that may occur under global climate change. This article is protected by copyright. All rights reserved.
      PubDate: 2015-04-08T01:49:08.480832-05:
      DOI: 10.1111/1365-2656.12376
       
  • Antagonistic effect of helpers on breeding male and female survival in a
           cooperatively breeding bird
    • Authors: Matthieu Paquet; Claire Doutrelant, Ben J. Hatchwell, Claire N. Spottiswoode, Rita Covas
      Abstract: 1.Cooperatively breeding species are typically long‐lived and hence, according to theory, are expected to maximise their lifetime reproductive success through maximising survival. Under these circumstances, the presence of helpers could be used to lighten the effort of current reproduction for parents to achieve higher survival. 2.In addition, individuals of different sexes and ages may follow different strategies, but whether male and female breeders and individuals of different ages benefit differently from the presence of helpers has often been overlooked. Moreover only one study that investigated the relationship between parental survival and the presence of helpers used Capture‐Mark‐Recaptures analyses (CMR). These methods are important since they allow us to account for the non‐detection of individuals that are alive in the population but not detected, and thus the effects on survival and recapture probability to be disentangled. 3.Here we used multi‐event CMR methods to investigate whether the number of helpers was associated with an increase in survival probability for male and female breeders of different ages in the sociable weaver Philetairus socius. In this species, both sexes reduce their feeding rate in presence of helpers. We therefore predicted that the presence of helpers should increase the breeders’ survival in both sexes, especially early in life when individuals potentially have more future breeding opportunities. In addition, sociable weaver females reduce their investment in eggs in the presence of helpers, so we predicted a stronger effect of helpers on female than male survival. 4.As expected we found that females had a higher survival probability when breeding with more helpers. Unexpectedly, however, male survival probability decreased with increasing number of helpers. This antagonistic effect diminished as the breeders grew older. 5.These results illustrate the complexity of fitness costs and benefits underlying cooperative behaviours and how these may vary with the individuals’ sex and age. They also highlight the need for further studies on the sex‐specific effects of helpers on survival. This article is protected by copyright. All rights reserved.
      PubDate: 2015-04-08T01:48:53.143626-05:
      DOI: 10.1111/1365-2656.12377
       
  • Wolves adapt territory size, not pack size to local habitat quality
    • Authors: Andrew M. Kittle; Morgan Anderson, Tal Avgar, James A. Baker, Glen S. Brown, Jevon Hagens, Ed Iwachewski, Scott Moffatt, Anna Mosser, Brent R. Patterson, Douglas E.B. Reid, Arthur R. Rodgers, Jen Shuter, Garrett M. Street, Ian D. Thompson, Lucas M. Vander Vennen, John M. Fryxell
      Abstract: 1.Although local variation in territorial predator density is often correlated with habitat quality, the causal mechanism underlying this frequently observed association is poorly understood and could stem from facultative adjustment in either group size or territory size. 2.To test between these alternative hypotheses we used a novel statistical framework to construct a winter population‐level utilization distribution for wolves (Canis lupus) in northern Ontario, which we then linked to a suite of environmental variables to determine factors influencing wolf space use. Next we compared habitat quality metrics emerging from this analysis as well as an independent measure of prey abundance, with pack size and territory size to investigate which hypothesis was most supported by the data. 3.We show that wolf space use patterns were concentrated near deciduous, mixed deciduous/coniferous and disturbed forest stands favoured by moose (Alces alces), the predominant prey species in the diet of wolves in northern Ontario, and in proximity to linear corridors, including shorelines and road networks remaining from commercial forestry activities. 4.We then demonstrate that landscape metrics of wolf habitat quality – projected wolf use, probability of moose occupancy and proportion of preferred land cover classes ‐ were inversely related to territory size but unrelated to pack size. 5.These results suggest that wolves in boreal ecosystems alter territory size, but not pack size, in response to local variation in habitat quality. This could be an adaptive strategy to balance tradeoffs between territorial defense costs and energetic gains due to resource acquisition. That pack size was not responsive to habitat quality suggests that variation in group size is influenced by other factors such as intra‐specific competition between wolf packs. This article is protected by copyright. All rights reserved.
      PubDate: 2015-04-06T08:33:50.619013-05:
      DOI: 10.1111/1365-2656.12366
       
  • Flowering time of butterfly nectar food plants is more sensitive to
           temperature than the timing of butterfly adult flight
    • Authors: Heather M. Kharouba; Mark Vellend
      Abstract: Variation among species in their phenological responses to temperature change suggests that shifts in the relative timing of key life cycle events between interacting species are likely to occur under climate warming. However, it remains difficult to predict the prevalence and magnitude of these shifts given that there have been few comparisons of phenological sensitivities to temperature across interacting species. Here, we used a broad‐scale approach utilizing collection records to compare the temperature sensitivity of the timing of adult flight in butterflies vs. flowering of their potential nectar food plants (days/°C) across space and time in British Columbia, Canada. On average, the phenology of both butterflies and plants advanced in response to warmer temperatures. However, the two taxa were differentially sensitive to temperature across space vs. across time, indicating the additional importance of non‐temperature cues and/or local adaptation for many species. Across butterfly‐plant associations, flowering time was significantly more sensitive to temperature than the timing of butterfly flight and these sensitivities were not correlated. Our results indicate that warming‐driven shifts in the relative timing of life cycle events between butterflies and plants are likely to be prevalent, but that predicting the magnitude and direction of such changes in particular cases is going to require detailed, fine‐scale data. This article is protected by copyright. All rights reserved.
      PubDate: 2015-03-31T04:19:03.570022-05:
      DOI: 10.1111/1365-2656.12373
       
  • Shape up or ship out: migratory behaviour predicts morphology across
           spatial scale in a freshwater fish
    • Authors: Ben B. Chapman; Kaj Hulthén, Christer Brönmark, P. Anders Nilsson, Christian Skov, Lars‐Anders Hansson, Jakob Brodersen
      Abstract: 1.Migration is a widespread phenomenon, with powerful ecological and evolutionary consequences. Morphological adaptations to reduce the energetic costs associated with migratory transport are commonly documented for migratory species. However few studies have investigated whether variation in body morphology can be explained by variation in migratory strategy within a species. 2.We address this question in roach Rutilus rutilus, a partially migratory freshwater fish that migrates from lakes into streams during winter. We both compare body shape between populations that differ in migratory opportunity (open versus closed lakes), and between individuals from a single population that vary in migratory propensity (migrants and residents from a partially migratory population). Following hydrodynamic theory, we posit that migrants should have a more shallow body depth, to reduce the costs associated with migrating into streams with higher flow conditions than the lakes the residents occupy all year round. 3.We find evidence both across and within‐populations to support our prediction, with individuals from open lakes and migrants from the partially migratory population having a more slender, shallow‐bodied morphology than fish from closed lakes and all‐year residents. 4.Our data suggest that a shallow body morphology is beneficial to migratory individuals and our study is one of the first to link migratory strategy and intraspecific variation in body shape. This article is protected by copyright. All rights reserved.
      PubDate: 2015-03-30T10:04:53.146635-05:
      DOI: 10.1111/1365-2656.12374
       
  • Optimal population prediction of sandhill crane recruitment based on
           climate‐mediated habitat limitations
    • Authors: Brian D. Gerber; William L. Kendall, Mevin B. Hooten, James A. Dubovsky, Roderic C. Drewien
      Abstract: 1.Prediction is fundamental to scientific inquiry and application; however, ecologists tend to favor explanatory modeling. We discuss a predictive modeling framework to evaluate ecological hypotheses and to explore novel/unobserved environmental scenarios to assist conservation and management decision makers. We apply this framework to develop an optimal predictive model for juvenile (
      PubDate: 2015-03-24T07:54:44.165516-05:
      DOI: 10.1111/1365-2656.12370
       
  • Informed herbivore movement and interplant communication determine the
           effects of induced resistance in an individual‐based model
    • Authors: Ilan N. Rubin; Stephen P. Ellner, Andre Kessler, Kimberly A. Morrell
      Abstract: 1.Plant induced resistance to herbivory affects the spatial distribution of herbivores, as well as their performance. In recent years, theories regarding the benefit to plants of induced resistance have shifted from ideas of optimal resource allocation towards a more eclectic set of theories that consider spatial and temporal plant variability and the spatial distribution of herbivores among plants. However, consensus is lacking on whether induced resistance causes increased herbivore aggregation or increased evenness, as both trends have been experimentally documented. 2.We created a spatial individual‐based model that can describe many plant‐herbivore systems with induced resistance, in order to analyze how different aspects of induced resistance might affect herbivore distribution, and the total damage to a plant population, during a growing season. 3.We analyze the specific effects on herbivore aggregation of informed herbivore movement (preferential movement to less‐damaged plants) and of information transfer between plants about herbivore attacks, in order to identify mechanisms driving both aggregation and evenness. We also investigate how the resulting herbivore distributions affect the total damage to plants and aggregation of damage. 4.Even, random and aggregated herbivore distributions can all occur in our model with induced resistance. Highest levels of aggregation occurred in the models with informed herbivore movement, and the most even distributions occurred when the average number of herbivores per plant was low. With constitutive resistance only random distributions occur. Damage to plants was spatially correlated, unless plants recover very quickly from damage; herbivore spatial autocorrelation was always weak. 5.Our model and results provide a simple explanation for the apparent conflict between experimental results indicating that both increased aggregation and increased evenness of herbivores can result from induced resistance. We demonstrate that information transfer from plants to herbivores, and from plants to neighboring plants, can both be major factors in determining nonrandom herbivore distributions. This article is protected by copyright. All rights reserved.
      PubDate: 2015-03-23T07:00:30.317305-05:
      DOI: 10.1111/1365-2656.12369
       
  • Global patterns and predictors of fish species richness in estuaries
    • Authors: Rita P. Vasconcelos; Sofia Henriques, Susana França, Stéphanie Pasquaud, Inês Cardoso, Marina Laborde, Henrique N. Cabral
      Abstract: 1.Knowledge on global patterns of biodiversity and regulating variables is indispensable to develop predictive models. 2.The present study used predictive modelling approaches to investigate hypotheses that explain the variation in fish species richness between estuaries over a worldwide spatial extent. Ultimately, such models will allow assessment of future changes in ecosystem structure and function as a result of environmental changes. 3.A comprehensive worldwide database was compiled on the fish assemblage composition and environmental characteristics of estuaries. Generalized Linear Models were used to quantify how variation in species richness among estuaries is related to historical events, energy dynamics, and ecosystem characteristics, whilst controlling for sampling effect. 4.At the global extent, species richness differed among marine biogeographic realms and continents, and increased with mean sea surface temperature, terrestrial net primary productivity, and the stability of connectivity with marine ecosystem (open versus temporarily open estuaries). At a smaller extent (within marine biogeographic realm or continent) other characteristics were also important in predicting variation in species richness, with species richness increasing with estuary area and continental shelf width. 5.The results suggest that species richness in an estuary is defined by predictors that are spatially hierarchical. Over the largest spatial extents species richness is influenced by the broader distributions and habitat use patterns of marine and freshwater species that can colonize estuaries, which are in turn governed by history contingency, energy dynamics and productivity variables. Species richness is also influenced by more regional and local parameters that can further affect the process of community colonization in an estuary including the connectivity of the estuarine with the adjacent marine habitat, and, over smaller spatial extents, the size of these habitats. In summary, patterns of species richness in estuaries across large spatial extents seem to reflect from global to local processes acting on community colonization. The importance of considering spatial extent, sampling effects and of combining history and contemporary environmental characteristics when exploring biodiversity is highlighted. This article is protected by copyright. All rights reserved.
      PubDate: 2015-03-18T22:35:30.023007-05:
      DOI: 10.1111/1365-2656.12372
       
  • Plant resistance reduces the strength of consumptive and
           non‐consumptive effects of predators on aphids
    • Authors: Mônica F. Kersch‐Becker; Jennifer S. Thaler
      Abstract: 1.The impact of predators on prey has traditionally been attributed to the act of consumption. Prey responses to the presence of the predator (non‐consumptive effects), however, can be as important as predation itself. While plant defenses are known to influence predator‐prey interactions, their relative effects on consumptive versus non‐consumptive effects are not well understood. 2.We evaluated the consequences of plant resistance and predators (Hippodamia convergens) on the mass, number of nymphs, population growth, density, and dispersal of aphids (Macrosiphum euphorbiae). We tested for the effects of plant resistance on non‐consumptive and consumptive effects of predators on aphid performance and dispersal using a combination of path analysis and experimental manipulation of predation risk. 3.We manipulated plant resistance using genetically modified lines of tomato (Solanum lycopersicum) that vary incrementally in the expression of the jasmonate pathway, which mediates induced resistance to insects and manipulated aphid exposure to lethal and risk predators. Predation risk predators had mandibles impaired to prevent killing. 4.Plant resistance reduced predation rate (consumptive effect) on high‐resistance plants. As a consequence, predators had no impact on the number of nymphs, aphid density or population growth on high‐resistance plants, whereas on low‐resistance plants predators reduced aphid density by 35% and population growth by 86%. Path analysis and direct manipulation of predation risk showed that predation risk rather than predation rate promoted aphid dispersal, and varied with host plant resistance. Aphid dispersal in response to predation risk was greater on low‐ compared to high‐resistance plants. The predation risk experiment also showed that the number of aphid nymphs increased in the presence of risk predators but did not translate into increased population growth. 5.In conclusion, the consumptive and non‐consumptive components of predators affect different aspects of prey demography, acting together to shape prey population dynamics. While predation risk accounts for most of the total effect of the predator on aphid dispersal and number of nymphs, the suppressive effect of predators on aphid population occurred largely through consumption. These effects are strongly influenced by plant resistance levels, suggesting that they are context dependent. This article is protected by copyright. All rights reserved.
      PubDate: 2015-03-18T04:49:08.771202-05:
      DOI: 10.1111/1365-2656.12371
       
  • Habitat fragmentation alters the properties of a host‐parasite
           network: rodents and their helminths in South‐East Asia
    • Authors: Frédéric Bordes; Serge Morand, Shai Pilosof, Julien Claude, Boris R. Krasnov, Jean‐François Cosson, Yannick Chaval, Alexis Ribas, Kittipong Chaisiri, Kim Blasdell, Vincent Herbreteau, Stéphane Dupuy, Annelise Tran
      Abstract: 1.While the effects of deforestation and habitat fragmentation on parasite prevalence or richness are well investigated, host‐parasite networks are still understudied despite their importance in understanding the mechanisms of these major disturbances. Because fragmentation may negatively impact species occupancy, abundance and co‐occurrence, we predict a link between spatiotemporal changes in habitat and the architecture of host‐parasite networks. 2.For this we used an extensive data set on 16 rodent species and 29 helminth species from 7 localities of South‐East Asia. We analysed the effects of rapid deforestation on connectance and modularity of helminth‐parasite networks. We estimated both the degree of fragmentation and the rate of deforestation through the development of land uses and their changes through the last 20 to 30 years in order to take into account the dynamics of habitat fragmentation in our statistical analyses. 3.We found that rapid fragmentation does not affect helminth species richness per se but impacts host‐parasite interactions as the rodent‐helminth network becomes less connected and more modular. 4.Our results suggest that parasite sharing among host species may become more difficult to maintain with the increase of habitat disturbance. This article is protected by copyright. All rights reserved.
      PubDate: 2015-03-16T17:28:59.990357-05:
      DOI: 10.1111/1365-2656.12368
       
  • Can habitat selection predict abundance'
    • Authors: Mark S. Boyce; Chris J. Johnson, Evelyn H. Merrill, Scott E. Nielsen, Erling J. Solberg, Bram Moorter
      Abstract: Habitats have substantial influence on the distribution and abundance of animals. Animals’ selective movement yields their habitat use. Animals generally are more abundant in habitats that are selected most strongly. Models of habitat selection can be used to distribute animals on the landscape or their distribution can be modeled based on data of habitat use, occupancy, intensity of use, or counts of animals. When the population is at carrying capacity or in an ideal free distribution, habitat selection and related metrics of habitat use can be used to estimate abundance. If the population is not at equilibrium, models have the flexibility to incorporate density into models of habitat selection; but abundance might be influenced by factors influencing fitness that are not directly related to habitat thereby compromising the use of habitat‐based models for predicting population size. Scale and domain of the sampling frame, both in time and space, are crucial considerations limiting application of these models. Ultimately, identifying reliable models for predicting abundance from habitat data requires an understanding of the mechanisms underlying population regulation and limitation. This article is protected by copyright. All rights reserved.
      PubDate: 2015-03-16T02:44:25.832642-05:
      DOI: 10.1111/1365-2656.12359
       
  • Ant–mediated ecosystem functions on a warmer planet: effects on soil
           movement, decomposition and nutrient cycling
    • Authors: Israel Del Toro; Relena R. Ribbons, Aaron M. Ellison
      Abstract: 1.Direct and indirect consequences of global warming on ecosystem functions and processes mediated by invertebrates remain understudied but are likely to have major impacts on ecosystems in the future. Among animals, invertebrates are taxonomically diverse, responsive to temperature changes, and play major ecological roles which also respond to temperature changes. 2.We used a mesocosm experiment to evaluate impacts of two warming treatments (+3.5 and + 5 °C, set points) and the presence and absence of the ant Formica subsericea (a major mediator of processes in north‐temperate ecosystems) on decomposition rate, soil movement, soil respiration, and nitrogen availability. 3.Replicate 19‐Litre mesocosms were placed outdoors in lathe houses and continuously warmed for 30 days in 2011 and 85 days in 2012. Warming treatments mimicked expected temperature increases for future climates in eastern North America. 4.In both years, the amount of soil displaced and soil respiration increased in the warming and ant presence treatments (soil movement: 73 – 119%; soil respiration: 37 – 48% relative to the control treatments without ants). 5.Decomposition rate and nitrogen availability tended to decrease in the warmest treatments (decomposition rate: ‐26 – ‐30%; nitrate availability: ‐11 – ‐42%). 6.Path analyses indicated that ants had significant short term direct and indirect effects on the studied ecosystem processes. These results suggest that ants may be moving more soil and building deeper nests to escape increasing temperatures, but warming may also influence their direct and indirect effects on soil ecosystem processes. This article is protected by copyright. All rights reserved.
      PubDate: 2015-03-13T08:59:00.994513-05:
      DOI: 10.1111/1365-2656.12367
       
  • Host age modulates parasite infectivity, virulence and reproduction
    • Authors: Rony Izhar; Frida Ben‐Ami
      Abstract: 1.Host age is one of the most striking differences among hosts within most populations, but there is very little data on how age‐dependent effects impact ecological and evolutionary dynamics of both the host and the parasite. 2.Here we examined the influence of host age (juveniles, young and old adults) at parasite exposure on host susceptibility, fecundity and survival as well as parasite transmission, using two clones of the water flea Daphnia magna and two clones of its bacterial parasite Pasteuria ramosa. 3.Younger D. magna were more susceptible to infection than older ones, regardless of host or parasite clone. Also, younger‐infected D. magna became castrated faster than older hosts, but host and parasite clone effects contributed to this trait as well. Furthermore, the early‐infected D. magna produced considerably more parasite transmission stages than late‐infected ones, while host age at exposure did not affect virulence as it is defined in models (host mortality). 4.When virulence is defined more broadly as the negative effects of infection on host fitness, by integrating the parasitic effects on host fecundity and mortality, then host age at exposure seems to slide along a negative relationship between host and parasite fitness. Thus, the virulence‐transmission trade‐off differs strongly among age classes, which in turn affects predictions of optimal virulence. 5.Age‐dependent effects on host susceptibility, virulence and parasite transmission could pose an important challenge for experimental and theoretical studies of infectious disease dynamics and disease ecology. Our results present a call for a more explicit stage‐structured theory for disease, which will incorporate age‐dependent epidemiological parameters. This article is protected by copyright. All rights reserved.
      PubDate: 2015-02-09T00:56:28.845454-05:
      DOI: 10.1111/1365-2656.12352
       
  • Indirect effects of predators control herbivore richness and abundance in
           a benthic eelgrass (Zostera marina) mesograzer community
    • Authors: Sarah L. Amundrud; Diane S. Srivastava, Mary I. O'Connor
      Abstract: 1.Herbivore communities can be sensitive to changes in predator pressure (top‐down effects) and resource availability (bottom‐up effects) in a wide range of systems. However, it remains unclear whether such top‐down and bottom‐up effects reflect direct impacts of predators and/or resources on herbivores, or are indirect, reflecting altered interactions amongst herbivore species. 2.We quantified direct and indirect effects of bottom‐up and top‐down processes on an eelgrass (Zostera marina) herbivore assemblage. In a field experiment, we factorially manipulated water column nutrients (with Osmocote™ slow‐release fertilizer) and predation pressure (with predator‐exclusion cages) and measured the effects on herbivore abundance, richness, and beta diversity. We examined likely mechanisms of community responses by statistically exploring the response of individual herbivore species to trophic manipulations. 3.Predators increased herbivore richness and total abundance, in both cases through indirect shifts in community composition. Increases in richness occurred through predator suppression of common gammarid amphipod species (Monocorophium acherusicum and Photis brevipes), permitting the inclusion of rarer gammarid species (Aoroides columbiae and Pontogeneia rostrata). Increased total herbivore abundance reflected increased abundance of a caprellid amphipod species (Caprella sp.), concurrent with declines in the abundance of other common species. Furthermore, predators decreased beta diversity by decreasing variability in Caprella sp. abundance among habitat patches. 4.Osmocote™ fertilization increased nutrient concentrations locally, but nutrients dissipated to background levels within 3 m of the fertilizer. Nutrient addition weakly affected the herbivore assemblage, not affecting richness and increasing total abundance by increasing one herbivore species (Caprella sp.). Nutrient addition did not affect beta diversity. 5.We demonstrated that assemblage‐level effects of trophic manipulations on community structure are the result of distinct and often indirect responses of herbivore species. These results underscore the importance of understanding herbivore‐herbivore interactions in a system commonly subjected to both eutrophication and overfishing. This article is protected by copyright. All rights reserved.
      PubDate: 2015-02-09T00:51:52.168881-05:
      DOI: 10.1111/1365-2656.12350
       
  • Discriminative host sanction together with relatedness promote the
           cooperation in fig/fig wasp mutualism
    • Authors: Rui‐Wu Wang; Bao‐Fa Sun, Yan Yang
      Abstract: 1.Sanctioning or punishing are regarded as one of most important dynamics in the evolution of cooperation. However, it has not been empirically examined yet whether or not such enforcement selection by sanctioning or punishing and classical theories like kin or reciprocity selection are separate mechanisms contributing to the evolution of cooperation. In addition, it remains largely unclear what factors determine the intensity or effectiveness of sanction. 2.Here we show that in the obligate, inter‐specific cooperation between figs and fig wasps, the hosted figs can discriminatively sanction cheating individuals by decreasing the offspring development ratio. Concurrently, the figs can reward the cooperative pollinators with a higher offspring development ratio. This sanction intensity and effectiveness largely depend on how closely the host and symbiont are related either in terms of reciprocity exchange or genetic similarity as measured by the reciprocal of the foundress number. 3.Our results imply that in asymmetric systems, symbionts might be forced to evolve to be cooperative or even altruistic through discriminative sanction against the non‐cooperative symbiont and reward to the cooperative symbiont by the host (i.e., through a game of “carrot and stick”). This article is protected by copyright. All rights reserved.
      PubDate: 2015-02-09T00:51:36.547257-05:
      DOI: 10.1111/1365-2656.12351
       
  • The crabs that live where hot and cold collide
    • Authors: Andrew R. Thurber
      Pages: 889 - 891
      Abstract: The distribution of Kiwa tyleri with the large male individual in the high‐temperature flow (right hand side ‐ fluid flow indicated by shimmering water) and the mixed sex assemblage (left). Note the heavy coat of epibiotic bacteria (grey colouring) on the individual in the hottest section of the vent, as expected from being closest to the sulphide needed to sustain the epibiotic bacteria that this species harvests for its food. Image courtesy of Dr. L. Marsh (Credit: NERC ChEsSo Consortium). In Focus: Marsh, L., Copley, J.T., Tyler, P.A. & Thatje, S. (2015) In hot and cold water: differential life‐history traits are key to success in contrasting thermal deep‐sea environments. Journal of Animal Ecology, 84, 898–913. Southern Ocean hydrothermal vents juxtapose two extremes – intense food‐poor cold and scalding food‐rich oases. At these vents, Marsh et al. (2015) found a community of Kiwa (Yeti) crabs that separated themselves along this gradient with the largest males sitting in hot, food‐rich waters, while smaller males and females co‐occur in an intermediate zone of warmth. However, as their eggs start to develop, females embark away from the vent to the food‐poor yet stable cold of the Southern Ocean. This species has found an intriguing way to balance foraging risk and population persistence at the interface of hot and cold.
      PubDate: 2015-06-23T07:46:11.848266-05:
      DOI: 10.1111/1365-2656.12398
       
  • In hot and cold water: differential life‐history traits are key to
           success in contrasting thermal deep‐sea environments
    • Authors: Leigh Marsh; Jonathan T. Copley, Paul A. Tyler, Sven Thatje
      First page: 898
      Abstract: Few species of reptant decapod crustaceans thrive in the cold‐stenothermal waters of the Southern Ocean. However, abundant populations of a new species of anomuran crab, Kiwa tyleri, occur at hydrothermal vent fields on the East Scotia Ridge. As a result of local thermal conditions at the vents, these crabs are not restricted by the physiological limits that otherwise exclude reptant decapods south of the polar front. We reveal the adult life history of this species by piecing together variation in microdistribution, body size frequency, sex ratio, and ovarian and embryonic development, which indicates a pattern in the distribution of female Kiwaidae in relation to their reproductive development. High‐density ‘Kiwa’ assemblages observed in close proximity to sources of vent fluids are constrained by the thermal limit of elevated temperatures and the availability of resources for chemosynthetic nutrition. Although adult Kiwaidae depend on epibiotic chemosynthetic bacteria for nutrition, females move offsite after extrusion of their eggs to protect brooding embryos from the chemically harsh, thermally fluctuating vent environment. Consequently, brooding females in the periphery of the vent field are in turn restricted by low‐temperature physiological boundaries of the deep‐water Southern Ocean environment. Females have a high reproductive investment in few, large, yolky eggs, facilitating full lecithotrophy, with the release of larvae prolonged, and asynchronous. After embryos are released, larvae are reliant on locating isolated active areas of hydrothermal flow in order to settle and survive as chemosynthetic adults. Where the cold water restricts the ability of all adult stages to migrate over long distances, these low temperatures may facilitate the larvae in the location of vent sites by extending the larval development period through hypometabolism. These differential life‐history adaptations to contrasting thermal environments lead to a disjunct life history among males and females of K. tyleri, which is key to their success in the Southern Ocean vent environment. We highlight the complexity in understanding the importance of life‐history biology, in combination with environmental, ecological and physiological factors contributing to the overall global distribution of vent‐endemic species. This paper reveals key features of the life‐history biology of the visually dominant species at newly discovered Antarctic deep‐sea hydrothermal vents, demonstrating contrasting influences of hydrothermal and polar deep‐sea conditions on distribution, population structure, sex‐ratio, reproductive development and global biogeography of vent endemic species.
      PubDate: 2015-03-02T19:47:51.418857-05:
      DOI: 10.1111/1365-2656.12337
       
  • Habitat traits and species interactions differentially affect abundance
           and body size in pond‐breeding amphibians
    • Authors: Brittany H. Ousterhout; Thomas L. Anderson, Dana L. Drake, William E. Peterman, Raymond D. Semlitsch
      First page: 914
      Abstract: 1.In recent studies habitat traits have emerged as stronger predictors of species occupancy, abundance, richness and diversity than competition. However, in many cases it remains unclear whether habitat also mediates processes more subtle than competitive exclusion, such as growth, or if intra‐ and interspecific interactions among individuals of different species may be a better predictor of size. 2.To test whether habitat traits are a stronger predictor of abundance and body size than intra‐ and interspecific interactions, we measured the density and body size of three species of larval salamanders in 192 ponds across a landscape. 3.We found that the density of larvae was best predicted by models that included habitat features, while models incorporating interactions among individuals of different species best explained the body size of larvae. Additionally, we found a positive relationship between focal species density and congener density, while focal species body size was negatively related to congener density. 4.We posit that salamander larvae may not experience competitive exclusion, and thus reduced densities, but instead compensate for increased competition behaviorally (e.g. reduced foraging), resulting in decreased growth. The discrepancy between larval density and body size, a strong predictor of fitness in this system, also highlights a potential shortcoming in using density or abundance as a metric of habitat quality or population health. This article is protected by copyright. All rights reserved.
      PubDate: 2015-02-03T04:08:01.872334-05:
      DOI: 10.1111/1365-2656.12344
       
  • Spatial variation in age structure among colonies of a marine snake: the
           influence of ectothermy
    • Authors: Xavier Bonnet; François Brischoux, David Pinaud, Catherine Louise Michel, Jean Clobert, Richard Shine, Thomas Fauvel
      First page: 925
      Abstract: Several tetrapod lineages that have evolved to exploit marine environments (e.g., seals, seabirds, sea kraits) continue to rely upon land for reproduction; and thus, form dense colonies on suitable islands. In birds and mammals (endotherms) the offspring cannot survive without their parents. Terrestrial colonies contain all age classes. In reptiles (ectotherms) this constraint is relaxed, because offspring are independent from birth. Hence, each age class has the potential to select sites with characteristics that favour them. Our studies of sea snakes (sea kraits) in the lagoon of New Caledonia reveal marked spatial heterogeneity in age structure among colonies. Sea krait colonies exhibit the endothermic “seal‐seabird” pattern (mixed age classes within populations) only where the lagoon is narrow. Where the lagoon is wide, most snake colonies are comprised primarily of a single age cohort. Nurseries are located near the coast, adult colonies offshore, and mixed colonies in between. We suggest that ectothermy allows individuals to utilize habitats that are best‐suited to their own ecological requirements, a flexibility not available to endothermic marine taxa with obligate parental care. This article is protected by copyright. All rights reserved.
      PubDate: 2015-03-16T02:44:54.004887-05:
      DOI: 10.1111/1365-2656.12358
       
  • The interaction between the spatial distribution of resource patches and
           population density: consequences for intra‐specific growth and
           morphology
    • Authors: Bailey Jacobson; James W. A. Grant, Pedro R. Peres‐Neto
      First page: 934
      Abstract: 1.How individuals within a population distribute themselves across resource patches of varying quality has been an important focus of ecological theory. The Ideal Free Distribution predicts equal fitness among individuals in a 1:1 ratio with resources, whereas resource defence theory predicts different degrees of monopolization (fitness variance) as a function of temporal and spatial resource clumping and population density. 2.One overlooked landscape characteristic is the spatial distribution of resource patches, altering the equitability of resource accessibility and thereby the effective number of competitors. While much work has investigated the influence of morphology on competitive ability for different resource types, less is known regarding the phenotypic characteristics conferring relative ability for a single resource type, particularly when exploitative competition predominates. 3.Here we used young‐of‐the‐year rainbow trout (Oncorhynchus mykiss) to test whether and how the spatial distribution of resource patches and population density interact to influence the level and variance of individual growth, as well as if functional morphology relates to competitive ability. Feeding trials were conducted within stream channels under three spatial distributions of 9 resource patches (distributed, semi‐ and clumped) at two density levels (9 and 27 individuals). 4.Average trial growth was greater in high‐density treatments with no effect of resource distribution. Within‐trial growth variance had opposite patterns across resource distributions. Here, variance decreased at low‐, but increased at high‐population densities as patches became increasingly clumped as the result of changes in the levels of interference versus exploitative competition. Within‐trial growth was related to both pre‐ and post‐trial morphology where competitive individuals were those with traits associated with swimming capacity and efficiency: larger heads/bodies/caudal fins and less angled pectoral fins. 5.The different degrees of within‐population growth variance at the same density level found here, as a function of spatial resource distribution, provides an explanation for the inconsistencies in within‐site growth variance and population regulation often noted with regards to density‐dependence in natural landscapes. This article is protected by copyright. All rights reserved.
      PubDate: 2015-04-06T08:34:11.414394-05:
      DOI: 10.1111/1365-2656.12365
       
  • Drivers of climate change impacts on bird communities
    • Authors: James W. Pearce‐Higgins; Sarah M. Eglington, Blaise Martay, Dan E. Chamberlain
      First page: 943
      Abstract: 1.Climate change is reported to have caused widespread changes to species’ populations and ecological communities. Warming has been associated with population declines in long‐distance migrants and habitat specialists, and increases in southerly distributed species. However, the specific climatic drivers behind these changes remain undescribed. 2.We analysed annual fluctuations in the abundance of 59 breeding bird species in England over 45 years to test the effect of monthly temperature and precipitation means upon population trends. 3.Strong positive correlations between population growth and both winter and breeding season temperature were identified for resident and short‐distance migrants. Lagged correlations between population growth and summer temperature and precipitation identified for the first time a widespread negative impact of hot, dry summer weather. Resident populations appeared to increase following wet autumns. Populations of long‐distance migrants were negatively affected by May temperature, consistent with a potential negative effect of phenological mismatch upon breeding success. There was evidence for some non‐linear relationships between monthly weather variables and population growth. 4.Habitat specialists and cold‐associated species showed consistently more negative effects of higher temperatures than habitat generalists and southerly‐distributed species associated with warm temperatures, suggesting that previously reported changes in community composition represent the accumulated effects of spring and summer warming. 5.Long‐term population trends were more significantly correlated with species’ sensitivity to temperature than precipitation, suggesting that warming had had a greater impact on population trends than changes in precipitation. Months where there had been the greatest warming were the most influential drivers of long‐term change. There was also evidence that species with the greatest sensitivity to extremes of precipitation have tended to decline. 6. Our results provide novel insights about the impact of climate change on bird communities. Significant lagged effects highlight the potential for altered species’ interactions to drive observed climate change impacts, although some community changes may have been driven by more immediate responses to warming. In England, resident and short‐distance migrant populations have increased in response to climate change, but potentially at the expense of long‐distance migrants, habitat‐specialists and cold‐associated species. This article is protected by copyright. All rights reserved.
      PubDate: 2015-04-06T08:30:16.588002-05:
      DOI: 10.1111/1365-2656.12364
       
  • Population size structure dependent fitness and ecosystem consequences in
           trinidadian guppies
    • Authors: Ronald D. Bassar; Thomas Heatherly, Michael C. Marshall, Steven A. Thomas, Alexander S. Flecker, David N. Reznick
      First page: 955
      Abstract: 1.Decades of theory and recent empirical results have shown that evolutionary, population, community and ecosystem properties are the result of feedbacks between ecological and evolutionary processes. The vast majority of theory and empirical research on these eco‐evolutionary feedbacks has focused on interactions among population size and mean traits of populations. 2.However, numbers and mean traits represent only a fraction of the possible feedback dimensions. Populations of many organisms consist of different size classes that differ in their impact on the environment and each other. Moreover, rarely do we know the map of ecological pathways through which changes in numbers or size structure cause evolutionary change. The goal of this study was to test the role of size structure in eco‐evolutionary feedbacks of Trinidadian guppies and to begin to build an eco‐evolutionary map along this unexplored dimension. 3.We used a factorial experiment in mesocosms wherein we crossed high and low predation guppy phenotypes with population size structure. We tested the ability of changes in size structure to generate selection on the demographic rates of guppies using an integral projection model (IPM). To understand how fitness differences among high and low predation phenotypes may be generated, we measured the response of the biomass of lower trophic levels and nutrient cycling to the different phenotype and size structure treatments. 4.We found a significant interaction between guppy phenotype and the size structure treatments for absolute fitness. Size structure had a very large effect on invertebrate biomass in the mesocosms, but there was little or no effect of the phenotype. The effect of size structure on algal biomass depended on guppy phenotype, with no difference in algal biomass in populations with more, smaller guppies, but a large decrease in algal biomass in mesocosms with phenotypes adapted to low predation risk. 5.These results indicate an important role for size structure partially driving eco‐evolutionary feedbacks in guppies. The changes in the ecosystem suggest that the absence of a steep decline in guppy fitness of the low predation risk populations is likely due to higher consumption of algae when invertebrates are comparatively rare. Overall, these results demonstrate size structure as a possible dimension through which eco‐evolutionary feedbacks may occur in natural populations. This article is protected by copyright. All rights reserved.
      PubDate: 2015-03-18T01:48:33.017414-05:
      DOI: 10.1111/1365-2656.12353
       
  • Detailed monitoring of a small but recovering population reveals sublethal
           effects of disease and unexpected interactions with supplemental feeding
    • Authors: Simon Tollington; Andrew Greenwood, Carl G. Jones, Paquita Hoeck, Aurélie Chowrimootoo, Donal Smith, Heather Richards, Vikash Tatayah, Jim J. Groombridge
      First page: 969
      Abstract: Infectious diseases are widely recognized to have substantial impact on wildlife populations. These impacts are sometimes exacerbated in small endangered populations, and therefore, the success of conservation reintroductions to aid the recovery of such species can be seriously threatened by outbreaks of infectious disease. Intensive management strategies associated with conservation reintroductions can further compound these negative effects in such populations. Exploring the sublethal effects of disease outbreaks among natural populations is challenging and requires longitudinal, individual life‐history data on patterns of reproductive success and other indicators of individual fitness. Long‐term monitoring data concerning detailed reproductive information of the reintroduced Mauritius parakeet (Psittacula echo) population collected before, during and after a disease outbreak was investigated. Deleterious effects of an outbreak of beak and feather disease virus (BFDV) were revealed on hatch success, but these effects were remarkably short‐lived and disproportionately associated with breeding pairs which took supplemental food. Individual BFDV infection status was not predicted by any genetic, environmental or conservation management factors and was not associated with any of our measures of immune function, perhaps suggesting immunological impairment. Experimental immunostimulation using the PHA (phytohaemagglutinin assay) challenge technique did, however, provoke a significant cellular immune response. We illustrate the resilience of this bottlenecked and once critically endangered, island‐endemic species to an epidemic outbreak of BFDV and highlight the value of systematic monitoring in revealing inconspicuous but nonetheless substantial ecological interactions. Our study demonstrates that the emergence of such an infectious disease in a population ordinarily associated with increased susceptibility does not necessarily lead to deleterious impacts on population growth and that negative effects on reproductive fitness can be short‐lived. Using long‐term monitoring data of a once critically endangered parakeet species, the authors document the effect on reproductive parameters of an epidemic outbreak of infectious disease. The negative effect on the population characterised by reduced hatch success was remarkably short‐lived and associated only with individuals which consumed supplemental food.
      PubDate: 2015-03-09T03:15:42.189511-05:
      DOI: 10.1111/1365-2656.12348
       
  • The path to host extinction can lead to loss of generalist parasites
    • Authors: Maxwell J. Farrell; Patrick R. Stephens, Lea Berrang‐Ford, John L. Gittleman, T. Jonathan Davies
      First page: 978
      Abstract: Host extinction can alter disease transmission dynamics, influence parasite extinction, and ultimately change the nature of host‐parasite systems. While theory predicts that single‐host parasites are among the parasite species most susceptible to extinction following declines in their hosts, documented parasite extinctions are rare. Using a comparative approach, we investigate how the richness of single‐host and multi‐host parasites is influenced by extinction risk among ungulate and carnivore hosts. Host‐parasite associations for free‐living carnivores (order Carnivora) and terrestrial ungulates (orders Perrisodactlya + Cetartiodactlya minus cetaceans) were merged with host trait data and IUCN Red List status to explore the distribution of single‐host and multi‐host parasites among threatened and non‐threatened hosts. We find that threatened ungulates harbour a higher proportion of single‐host parasites compared to non‐threatened ungulates, which is explained by decreases in the richness of multi‐host parasites. However, among carnivores threat status is not a significant predictor of the proportion of single‐host parasites, or the richness of single‐host or multi‐host parasites. The loss of multi‐host parasites from threatened ungulates may be explained by decreased cross‐species contact as hosts decline and habitats become fragmented. Among carnivores threat status may not be important in predicting patterns of parasite specificity because host decline results in equal losses of both single‐host parasites and multi‐host parasites through reduction in average population density and frequency of cross‐species contact. Our results contrast with current models of parasite coextinction and highlight the need for updated theories that are applicable across host groups and account for both inter and intraspecific contact. This article is protected by copyright. All rights reserved.
      PubDate: 2015-01-31T01:52:35.213789-05:
      DOI: 10.1111/1365-2656.12342
       
  • Differences in host species relationships and biogeographical influences
           produce contrasting patterns of prevalence, community composition and
           genetic structure in two genera of avian malaria parasites in southern
           Melanesia
    • Authors: Sophie Olsson‐Pons; Nicholas J. Clark, Farah Ishtiaq, Sonya M. Clegg
      First page: 985
      Abstract: 1.Host‐parasite interactions have the potential to influence broad scale ecological and evolutionary processes, levels of endemism, divergence patterns and distributions in host populations. Understanding the mechanisms involved requires identification of the factors that shape parasite distribution and prevalence. 2.A lack of comparative information on community‐level host‐parasite associations limits our understanding of the role of parasites in host population divergence processes. Avian malaria (haemosporodian) parasites in bird communities offer a tractable model system to examine the potential for pathogens to influence evolutionary processes in natural host populations. 3.Using cytochrome b variation, we characterized phylogenetic diversity and prevalence of two genera of avian haemosporidian parasites, Plasmodium and Haemoproteus, and analysed biogeographic patterns of lineages across islands and avian hosts, in southern Melanesian bird communities to identify factors that explain patterns of infection. 4.Plasmodium spp. displayed isolation by distance effects, a significant amount of genetic variation distributed among islands but insignificant amounts among host species and families, and strong local island effects with respect to prevalence. Haemoproteus spp. did not display isolation by distance patterns, showed significant structuring of genetic variation among avian host species and families, and significant host species prevalence patterns. 5.These differences suggest that Plasmodium spp. infection patterns were shaped by geography and the abiotic environment, whereas Haemoproteus spp. infection patterns were shaped predominantly by host associations. Heterogeneity in the complement and prevalence of parasite lineages infecting local bird communities likely exposes host species to a mosaic of spatially divergent disease selection pressures across their naturally fragmented distributions in southern Melanesia. Host associations for Haemoproteus spp. indicate a capacity for the formation of locally co‐adapted host‐parasite relationships, a feature that may limit intraspecific gene flow or range expansions of closely related host species. This article is protected by copyright. All rights reserved.
      PubDate: 2015-03-16T02:56:45.635066-05:
      DOI: 10.1111/1365-2656.12354
       
  • Context‐dependent survival, fecundity, and predicted
           population‐level consequences of brucellosis in African buffalo
    • Authors: Erin E. Gorsich; Vanessa O. Ezenwa, Paul C. Cross, Roy G. Bengis, Anna E. Jolles
      First page: 999
      Abstract: 1.Chronic infections may have negative impacts on wildlife populations, yet their effects are difficult to detect in the absence of long‐term population monitoring. Brucella abortus, the bacteria responsible for bovine brucellosis, causes chronic infections and abortions in wild and domestic ungulates, but its impact on population dynamics is not well understood. 2.We report infection patterns and fitness correlates of bovine brucellosis in African buffalo based on (1) seven years of cross‐sectional disease surveys and (2) a four‐year longitudinal study in Kruger National Park (KNP), South Africa. We then used a matrix population model to translate these observed patterns into predicted population‐level effects. 3.Annual brucellosis seroprevalence ranged from 8.7% (95% CI=1.8‐15.6) to 47.6% (95% CI=35.1‐60.1), increased with age until adulthood (>6), and varied by location within KNP. Animals were on average in worse condition after testing positive for brucellosis (F=‐5.074, p
      PubDate: 2015-03-18T02:08:44.874922-05:
      DOI: 10.1111/1365-2656.12356
       
  • Resources, key traits, and the size of fungal epidemics in Daphnia
           populations
    • Authors: David J. Civitello; Rachel M. Penczykowski, Aimee N. Smith, Marta S. Shocket, Meghan A. Duffy, Spencer R. Hall
      First page: 1010
      Abstract: Parasites can profoundly affect host populations and ecological communities. Thus, it remains critical to identify mechanisms that drive variation in epidemics. Resource availability can drive epidemics via traits of hosts and parasites that govern disease spread. Here, we map resource‐trait‐epidemic connections to explain variation in fungal outbreaks (Metschnikowia bicuspidata) in a zooplankton host (Daphnia dentifera) among lakes. We predicted epidemics would grow larger in lakes with more phytoplankton via three energetic mechanisms. First, resources should stimulate Daphnia reproduction, potentially elevating host density. Second, resources should boost body size of hosts, enhancing exposure to environmentally distributed propagules through size‐dependent feeding. Third, resources should fuel parasite reproduction within hosts. To test these predictions, we sampled 12 natural epidemics and tracked edible algae, fungal infection prevalence, body size, fecundity, and density of hosts, as well as within‐host parasite loads. Epidemics grew larger in lakes with more algal resources. Structural equation modeling revealed that resource availability stimulated all three traits (host fecundity, host size, and parasite load). However, only parasite load connected resources to epidemic size. Epidemics grew larger in more dense Daphnia populations, but host density was unrelated to host fecundity (thus breaking its link to resources). Thus, via energetic mechanisms, resource availability can stimulate key trait(s) governing epidemics in nature. A synthetic focus on resources and resource‐trait links could yield powerful insights into epidemics. This article is protected by copyright. All rights reserved.
      PubDate: 2015-03-21T09:21:22.199205-05:
      DOI: 10.1111/1365-2656.12363
       
  • Demographic mechanisms of inbreeding adjustment through extra‐pair
           reproduction
    • Authors: Jane M. Reid; A. Bradley Duthie, Matthew E. Wolak, Peter Arcese
      First page: 1029
      Abstract: 1.One hypothesis explaining extra‐pair reproduction is that socially monogamous females mate with extra‐pair males to adjust the coefficient of inbreeding (f) of extra‐pair offspring (EPO) relative to that of within‐pair offspring (WPO) they would produce with their socially‐paired male. Such adjustment of offspring f requires non‐random extra‐pair reproduction with respect to relatedness, which is in turn often assumed to require some mechanism of explicit pre‐copulatory or post‐copulatory kin discrimination. 2.We propose three demographic processes that could potentially cause mean f to differ between individual females’ EPO and WPO given random extra‐pair reproduction with available males without necessarily requiring explicit kin discrimination. Specifically, such a difference could arise if social pairings formed non‐randomly with respect to relatedness or persisted non‐randomly with respect to relatedness, or if the distribution of relatedness between females and their sets of potential mates changed during the period through which social pairings persisted. 3.We used comprehensive pedigree and pairing data from free‐living song sparrows (Melospiza melodia) to quantify these three processes and hence investigate how individual females could adjust mean offspring f through instantaneously random extra‐pair reproduction. 4.Female song sparrows tended to form social pairings with unrelated or distantly related males slightly less frequently than expected given random pairing within the defined set of available males. Furthermore, social pairings between more closely related mates tended to be more likely to persist across years than social pairings between less closely related mates. However, these effects were small and the mean relatedness between females and their sets of potential extra‐pair males did not change substantially across the years through which social pairings persisted. 5.Our framework and analyses illustrate how demographic and social structuring within populations might allow females to adjust mean f of offspring through random extra‐pair reproduction without necessarily requiring explicit kin discrimination, implying that adjustment of offspring f might be an inevitable consequence of extra‐pair reproduction. New theoretical and empirical studies are required to explore the general magnitude of such effects and the degree to which they could facilitate or constrain long‐term evolution of extra‐pair reproduction. This article is protected by copyright. All rights reserved.
      PubDate: 2015-02-02T08:41:37.597953-05:
      DOI: 10.1111/1365-2656.12340
       
  • Ecological opportunity leads to the emergence of an alternative
           behavioural phenotype in a tropical bird
    • Authors: Janeene M Touchton; Martin Wikelski
      First page: 1041
      Abstract: Loss of a dominant competitor can open ecological opportunities. Ecological opportunities are considered prerequisites for adaptive radiations. Nonetheless, initiation of diversification in response to ecological opportunity is seldom observed, so we know little about the stages by which behavioural variation either increases or coalesces into distinct phenotypes. Here, a natural experiment showed that in a tropical island's guild of army‐ant following birds, a new behavioural phenotype emerged in subordinate spotted antbirds (Hylophylax naevioides) after the socially dominant ocellated antbird (Phaenostictus mcleannani) died out. Individuals with this behavioural phenotype are less territorial; instead, they roam in search of ant swarms where they feed in locations from which dominant competitors formerly excluded them. Roaming individuals fledge more young than territorial individuals. We conclude that ecological opportunity arising from species loss may enhance the success of alternative behavioural phenotypes and can favour further intraspecific diversification in life‐history traits in surviving species. This article is protected by copyright. All rights reserved.
      PubDate: 2015-01-31T01:46:49.789493-05:
      DOI: 10.1111/1365-2656.12341
       
  • No apparent benefits of allonursing for recipient offspring and mothers in
           the cooperatively breeding meerkat
    • Authors: K. J MacLeod; K. E McGhee, T. H Clutton‐Brock
      First page: 1050
      Abstract: Cooperative behaviours by definition are those that provide some benefit to another individual. Allonursing, the nursing of non‐descendent young, is often considered a cooperative behavior and is assumed to provide benefits to recipient offspring in terms of growth and survival, and to their mothers, by enabling them to share the lactation load. However, these proposed benefits are not well understood, in part because maternal and litter traits and other ecological and social variables are not independent of one another, making patterns hard to discern using standard univariate analyses. Here, we investigate the potential benefits of allonursing in the cooperatively breeding Kalahari meerkat, where socially subordinate females allonurse the young of a dominant pair without having young of their own. We use structural equation modelling to allow us to account for the interdependence of maternal traits, litter traits and environmental factors. We find no evidence that allonursing provides benefits to pups or mothers. Pups that received allonursing were not heavier at emergence and did not have a higher survival rate than pups that did not receive allonursing. Mothers whose litters were allonursed were not in better physical condition, did not reconceive faster, and did not reduce their own nursing investment compared to mothers who nursed their litters alone. These patterns were not significantly influenced by whether mothers were in relatively good, or poor, condition. We suggest that allonursing may persist in this species because the costs to allonurses may be low. Alternatively allonursing may confer other, more cryptic, benefits to pups or allonurses, such as immunological or social benefits. This article is protected by copyright. All rights reserved.
      PubDate: 2015-01-31T02:03:51.549794-05:
      DOI: 10.1111/1365-2656.12343
       
  • Space‐use behavior of woodland caribou based on a cognitive movement
           model
    • Authors: Tal Avgar; James A. Baker, Glen S. Brown, Jevon S. Hagens, Andrew M. Kittle, Erin E. Mallon, Madeleine T. McGreer, Anna Mosser, Steven G. Newmaster, Brent R. Patterson, Douglas E. B. Reid, Art R. Rodgers, Jennifer Shuter, Garrett M. Street, Ian Thompson, Merritt J. Turetsky, Philip A. Wiebe, John M. Fryxell
      First page: 1059
      Abstract: Movement patterns offer a rich source of information on animal behavior and the ecological significance of landscape attributes. This is especially useful for species occupying remote landscapes where direct behavioral observations are limited. In this study we fit a mechanistic model of animal cognition and movement to GPS positional data of woodland caribou (Rangifer tarandus caribou; Gmelin 1788) collected over a wide range of ecological conditions. The model explicitly tracks individual animal informational state over space and time, with resulting parameter estimates that have direct cognitive and ecological meaning. Three biotic landscape attributes were hypothesized to motivate caribou movement: forage abundance (dietary digestible biomass), wolf (Canis lupus; Linnaeus, 1758) density, and moose (Alces alces; Linnaeus, 1758) habitat. Wolves are the main predator of caribou in this system and moose are their primary prey. Resulting parameter estimates clearly indicated that forage abundance is an important driver of caribou movement patterns, with predator and moose avoidance often having a strong effect, but not for all individuals. From the cognitive perspective, our results support the notion that caribou rely on limited sensory inputs from their surroundings, as well as on long‐term spatial memory, to make informed movement decisions. Our study demonstrates how sensory, memory and motion capacities may interact with ecological fitness covariates to influence movement decisions by free‐ranging animals. This article is protected by copyright. All rights reserved.
      PubDate: 2015-03-20T04:49:52.072333-05:
      DOI: 10.1111/1365-2656.12357
       
  • Patterns of trophic niche divergence between invasive and native fishes in
           wild communities are predictable from mesocosm studies
    • Authors: Thi Nhat Quyen Tran; Michelle C. Jackson, Danny Sheath, Hugo Verreycken, J. Robert Britton
      First page: 1071
      Abstract: 1.Ecological theory attempts to predict how impacts for native species arise from biological invasions. A fundamental question centres on the feeding interactions of invasive and native species: whether invasion will result in increased inter‐specific competition, which would result in negative consequences for the competing species, or trophic niche divergence, which would facilitate the invader's integration into the community and their co‐existence with native species. 2.Here, the feeding interactions of a highly invasive fish, topmouth gudgeon Pseudorasbora parva, with three native and functionally similar fishes were studied to determine whether patterns of either niche overlap or divergence detected in mesocosm experiments were apparent between the species at larger spatial scales. Using stable isotope analysis, their feeding relationships were assessed initially in the mesocosms (1000 L), and then in small ponds (< 400 square metres) and large ponds (> 600 square metres). 3.In the mesocosms, a consistent pattern of trophic niche divergence was evident between the sympatric fishes, with niches shifting further apart in isotopic space than suggested in allopatry, revealing that sharing of food resources was limited. Sympatric Pseudorasbora parva also had a smaller niche than their allopatric populations. 4.In eight small ponds where P. parva had coexisted for several years with at least one of the fish species used in the mesocosms, strong patterns of niche differentiation were also apparent, with P. parva always at a lower trophic position than the other fishes, as also occurred in the mesocosms. Where these fishes were sympatric within more complex fish communities in the large ponds, similar patterns were also apparent, with strong evidence of trophic niche differentiation. 5.Aspects of the ecological impacts of P. parva invasion for native communities in larger ponds were consistent with those in the mesocosm experiments. Their invasion resulted in divergence in trophic niches, partly due to their reduced niche widths when in sympatry with other species, facilitating their coexistence in invaded ecosystems. Our study highlights the utility of controlled mesocosm studies for predicting the trophic relationships that can develop from introductions of non‐native species into more complex ecosystems and at larger spatial scales. This article is protected by copyright. All rights reserved.
      PubDate: 2015-03-30T08:39:01.624524-05:
      DOI: 10.1111/1365-2656.12360
       
  • Determinants of Individual Foraging Specialisation in Large Marine
           Vertebrates, the Antarctic and Subantarctic Fur Seals
    • Authors: L. Kernaléguen; J. P. Y. Arnould, C. Guinet, Y. Cherel
      First page: 1081
      Abstract: 1.The degree of individual specialisation in resource use differs widely among wild populations where individuals range from fully generalised to highly specialised. This inter‐individual variation has profound implications in many ecological and evolutionary processes. A recent review proposed four main ecological causes of individual specialisation: inter‐ and intra‐specific competition, ecological opportunity and predation. 2.Using the isotopic signature of sub‐sampled whiskers, we investigated to what degree three of these factors (inter‐ and intra‐specific competition and ecological opportunity) affect the population niche width and the level of individual foraging specialisation in two fur seal species, the Antarctic and subantarctic fur seals (Arctocephalus gazella and A. tropicalis), over several years. 3.Population niche width was greater when the two seal species bred in allopatry (low inter‐specific competition) than in sympatry or when seals bred in high density stabilized colonies (high intra‐specific competition). In agreement with the Niche Variation Hypothesis (NVH), higher population niche width was associated with higher inter‐individual niche variation. However, in contrast with the NVH, all Antarctic females increased their niche width during the inter‐breeding period when they had potentially access to a wider diversity of foraging grounds and associated prey (high ecological opportunities), suggesting they all dispersed to a similar productive area. 4.The degree of individual specialisation varied among populations and within the annual cycle. Highest levels of inter‐individual variation were found in a context of lower inter‐ or higher intra‐specific competition. Contrasted results were found concerning the effect of ecological opportunity. Depending on seal species, females exhibited either a greater or lower degree of individual specialisation during the inter‐breeding period, reflecting species‐specific biological constraints during that period. 5.These results suggest a significant impact of ecological interactions on the population niche width and degree of individual specialisation. Such variation at the individual level may be an important factor in the species plasticity with significant consequences on how it may respond to environmental variability. This article is protected by copyright. All rights reserved.
      PubDate: 2015-02-02T09:45:42.500485-05:
      DOI: 10.1111/1365-2656.12347
       
  • Parasitoid wasps indirectly suppress seed production by stimulating
           consumption rates of their seed‐feeding hosts
    • Authors: Xinqiang Xi; Nico Eisenhauer, Shucun Sun
      First page: 1103
      Abstract: 1.In parasitoid‐herbivore‐plant food chains, parasitoids may be simultaneously linked with both herbivore hosts and plants, as occurs when herbivores attacked by parasitoids continue to consume plants although they are destined to die. This peculiar property may cause parasitoids to confer a differential trophic cascading effect on plants than that known for typical predators. 2.We hypothesized that larval koinobiont parasitoids would confer an immediate negative effect on plant seed production by stimulating consumption of their seed predator hosts. We tested this hypothesis in an alpine parasitic food chain of plant seeds, pre‐dispersal seed predators (tephritid fly larvae), and koinobiont parasitoids using field observations, a field experiment, and a microcosm study. 3.We first compared observed seed production in a) non‐infected capitula, b) capitula infected only by seed predators (tephritid flies), and c) capitula infected by both seed predators and their parasitoids in five Asteraceae species. Consistent with our hypothesis, seed loss in the capitula with both seed predators and parasitoids was significantly greater than in the capitula infested only by seed predators. 4.This effect was replicated in a controlled field experiment focusing on the most common parasitoid‐seed predator‐plant interaction chain in our system, in which confounding factors (e.g., density and phenology) were excluded. Here we show that parasitoids indirectly decreased plant seed production by changing the behavior of seed predators. 5.In a microcosm study we show that larval parasitoids significantly extended the growth period and increased the terminal size of their host tephritid maggots. Thus, parasitoids suppressed plant seed production by stimulating the growth and consumption of the fly maggots. 6.In contrast to the typical predator‐induced trophic cascade, we highlight the significance of parasitoids indirectly decreasing plant fitness by stimulating consumption by seed predators. Future studies on trophic interactions should consider the net effect of both increased consumption by seed predators and their death after development of parasitoids. This article is protected by copyright. All rights reserved.
      PubDate: 2015-03-20T04:49:25.781001-05:
      DOI: 10.1111/1365-2656.12361
       
  • Measuring β‐diversity with species abundance data
    • Authors: Louise J. Barwell; Nick J. B. Isaac, William E. Kunin
      First page: 1112
      Abstract: In 2003, 24 presence‐absence β‐diversity metrics were reviewed and a number of trade‐offs and redundancies identified. We present a parallel investigation into the performance of abundance‐based metrics of β‐diversity is lacking. β‐diversity is a multi‐faceted concept, central to spatial ecology. There are multiple metrics available to quantify it: the choice of metric is an important decision. We test 16 conceptual properties and two sampling properties of a β‐diversity metric: metrics should be 1) independent of α‐diversity and 2) cumulative along a gradient of species turnover. Similarity should be 3) probabilistic when assemblages are independently and identically distributed. Metrics should have 4) a minimum of zero and increase monotonically with the degree of 5) species turnover, 6) decoupling of species ranks and 7) evenness differences. However, complete species turnover should always generate greater values of β than extreme 8) ranks shifts or 9) evenness differences. Metrics should 10) have a fixed upper limit, 11) symmetry (βA,B=βB,A), 12) double‐zero asymmetry for double‐absences and double‐presences and 13) not decrease in a series of nested assemblages. Additionally, metrics should be independent of 14) species replication 15) the units of abundance and 16) differences in total abundance between sampling units. When samples are used to infer β‐diversity, metrics should be 1) independent of sample sizes and 2) independent of unequal sample sizes. We test 29 metrics for these properties and five “personality” properties. Thirteen metrics were outperformed or equalled across all conceptual and sampling properties. Differences in sensitivity to species’ abundance lead to a performance trade‐off between sample size bias and the ability to detect turnover among rare species. In general, abundance‐based metrics are substantially less biased in the face of undersampling, although the presence‐absence metric, βsim, performed well overall. Only βBaselga R turn, βBaselga B‐C turn and βsim measured purely species turnover and were independent of nestedness. Among the other metrics, sensitivity to nestedness varied >4‐fold. Our results indicate large amounts of redundancy among existing β‐diversity metrics, while the estimation of unseen shared and unshared species is lacking and should be addressed in the design of new abundance‐based metrics. This article is protected by copyright. All rights reserved.
      PubDate: 2015-03-21T09:21:27.315014-05:
      DOI: 10.1111/1365-2656.12362
       
  • To each its own: differential response of specialist and generalist
           herbivores to plant defence in willows
    • Authors: Martin Volf; Jan Hrcek, Riitta Julkunen‐Tiitto, Vojtech Novotny
      First page: 1123
      Abstract: 1.Plant‐insect food webs tend to be dominated by interactions resulting from diffuse coevolution between plants and multiple lineages of herbivores rather than by reciprocal coevolution and co‐cladogenesis. Plants therefore require defence strategies effective against a broad range of herbivore species. In one extreme, plants could develop a single universal defence effective against all herbivorous insects, or tailor‐made strategies for each herbivore species. The evolution and ecology of plant defence has to be studied with entire insect assemblages, rather than small subsets of pairwise interactions. 2.The present study examines whether specialists and generalists in three coexisting insect lineages, forming the leaf‐chewing guild, respond uniformly to plant phylogeny, secondary metabolites, nutrient content and mechanical anti‐herbivore defences of their hosts, thus permitting universal plant defence strategies against specialised and generalist folivorous insects from various taxa. 3.The extensive data on folivorous assemblages comprising three insect orders and 193 species are linked with plant phylogeny, secondary chemistry (salicylates, flavonoids and tannins), leaf morphological traits (SLA and trichome coverage), nutrient (C:N) content and growth‐form of eight willow (Salix) and one aspen (Populus) species growing in sympatry. 4.Generalists responded to overall host‐plant chemistry and trichomes, whilst specialists responded to host‐plant phylogeny and secondary metabolites that are unique to willows and that are capable of being utilised as an anti‐predator protection. We did not find any significant impact of other plant traits, i.e. specific leaf area, C:N ratio, flavonoids, tannins and growth‐form, on the composition of leaf‐chewing communities. 5.Our results show that the response to plant traits is differential among specialists and generalists. This finding constrains the ability of plants to develop defensive traits universally effective against herbivores and may lead to diversification of plant defensive mechanisms into several complementary syndromes, required for effective protection against generalists and specialists from multiple insect taxa comprising most leaf‐chewing assemblages. These results point to the necessity of broad studies of plant‐herbivore interactions, across multiple insect taxa and guilds. This article is protected by copyright. All rights reserved.
      PubDate: 2015-02-03T11:01:31.05106-05:0
      DOI: 10.1111/1365-2656.12349
       
  • Live fast, die old: no evidence of reproductive senescence or costs of
           mating in a damselfly (Odonata: Zygoptera)
    • Abstract: Recent examples of actuarial senescence in wild insect populations have challenged the long‐held assumption that the brevity of wild insect life spans precludes senescence. We investigate age‐related patterns in mating behaviour in adults of a short‐lived damselfly, Coenagrion puella and the implications of this mating. Using capture histories for 1033 individuals over two field seasons, we conduct both pooled and stratified analyses of variations in breeding activity. Pooled analyses suggest that there is strong age‐related variation in the probability of being present at the mating rendezvous. However, no age‐related variation was observed in the probability of mating. Stratified approaches confirmed a general pattern of age‐related declines in survival probability, but provided only equivocal evidence of an effect of age on transition between temporary breeding states. Mating males and females showed greater survival than non‐mating individuals, possibly as a consequence of higher body condition. Older males that were not currently breeding were less likely to commence breeding on the next day, but showed no patterns in breeding cessation. Overall, transitions between both breeding states declined with age, suggesting that males that breed tend to continue breeding while those that do not breed continue to be unsuccessful. Female mating rates were consistently high across all ages with no age‐related decline apparent. While previous research has demonstrated actuarial senescence in this population, as does this study, we find little evidence of either age‐related declines in reproductive behaviour or breeding‐related declines in survival, which might indicate functional senescence or costs of mating, respectively. Indeed, the greater survival in mating individuals of both sexes suggests that variations in individual quality may mediate both reproductive success and longevity. Contrary to recent studies, we found no compelling evidence for reproductive senescence or a cost of mating in an important and well‐studied model odonate. The possible link between condition and ageing suggests that individual quality needs to be taken into account when studying senescence. We recommend the use of multistrata models for the future investigation of these phenomena. In a previous study the authors demonstrated that older damselflies show signs of ageing despite their short lifespans, but in this comprehensive study the authors show that there appears to be neither a decline in reproductive performance nor a ‘cost of sex’ in terms of increased risk of mortality in breeding individuals.
       
  • Raccoon contact networks predict seasonal susceptibility to rabies
           outbreaks and limitations of vaccination
    • Abstract: Infectious disease transmission often depends on the contact structure of host populations. Although it is often challenging to capture the contact structure in wild animals, new technology has enabled biologists to obtain detailed temporal information on wildlife social contacts. In this study, we investigated the effects of raccoon contact patterns on rabies spread using network modeling. Raccoons (Procyon lotor) play an important role in the maintenance of rabies in the US. It is crucial to understand how contact patterns influence the spread of rabies in raccoon populations in order to design effective control measures and to prevent transmission to human populations and other animals. We constructed a dynamic system of contact networks based on empirical data from proximity logging collars on a wild suburban raccoon population, and then simulated rabies spread across these networks. Our contact networks incorporated the number and duration of raccoon interactions. We included differences in contacts according to sex and season, and both short‐term acquaintances and long‐term associations. Raccoons may display different behaviors when infectious, including aggression (furious behavior) and impaired mobility (dumb behavior); the network model was used to assess the impact of potential behavioral changes of rabid raccoons. We also tested the effectiveness of different vaccination coverage levels on rabies spread. Our results demonstrate that when rabies enters a suburban raccoon population, the likelihood of a disease outbreak affecting the majority of the population is high. Both the magnitude of rabies outbreaks and the speed of rabies spread depend strongly on the time of year that rabies is introduced into the population. When there is a combination of dumb and furious behaviors in the rabid raccoon population, there are similar outbreak sizes and speed of spread to when there are no behavioral changes due to rabies infection. By incorporating detailed data describing the variation in raccoon contact rates into a network modeling approach, we were able to show that suburban raccoon populations are highly susceptible to rabies outbreaks, that the risk of large outbreaks varies seasonally, and that current vaccination target levels may be inadequate to prevent the spread of rabies within these populations. Our findings thus provide new insights into rabies dynamics in raccoon populations and have important implications for disease control. This article is protected by copyright. All rights reserved.
       
  • Constructing, conducting, and interpreting animal social network analysis
    • Abstract: 1.Animal social networks are descriptions of social structure which, aside from their intrinsic interest for understanding sociality, can have significant bearing on across many fields of biology. 2.Network analysis provides a flexible toolbox for testing a broad range of hypotheses, and for describing the social system of species or populations in a quantitative and comparable manner. However, it requires careful consideration of underlying assumptions, in particular differentiating real from observed networks and controlling for inherent biases that are common in social data. 3.We provide a practical guide for using this framework to analyse animal social systems and test hypotheses. First, we discuss key considerations when defining nodes and edges, and when designing methods for collecting data. We then discuss different approaches for inferring social networks from these data and displaying them. We follow with an overview of methods for quantifying properties of nodes and networks, as well as for testing hypotheses concerning network structure and network processes. Finally, we provide information about assessing the power and accuracy of an observed network. 4.Alongside this manuscript, we provide appendices containing background information on common programming routines and worked examples of how to perform network analysis using the R programming language. 5.We conclude by discussing some of the major current challenges in social network analysis and interesting future directions. In particular, we highlight the under‐exploited potential of experimental manipulations on social networks to address research questions. This article is protected by copyright. All rights reserved.
       
  • A bust but no boom: Responses of floodplain bird assemblages during and
           after prolonged drought
    • Abstract: Climate change alters the frequency and severity of extreme events, such as drought. Such events will be increasingly important in shaping communities as climate change intensifies. The ability of species to withstand extreme events (resistance) and to recover once adverse conditions abate (resilience) will determine their persistence. We estimated the resistance and resilience of bird species during and after a 13‐yr drought (the ‘Big Dry’) in floodplain forests in southeastern Australia. We conducted bird surveys at the beginning and end of the Big Dry, and after the abrupt end to the drought (the ‘Big Wet’), to evaluate species‐specific changes in reporting rates among the three periods. We assessed changes in bird breeding activity before and after the Big Wet to estimate demographic resilience based on breeding. Between the start and the end of the Big Dry (1998 vs 2009), 37 of 67 species declined substantially. Of those, only two had increased reporting rates after the Big Wet (2009 vs 2013) that were equal to or larger than their declines, while three partially recovered. All other declining species showed low resilience: 25 showed no change in reporting rates and seven declined further. The number of breeding species and total breeding activity of all species declined after the Big Wet, and there was no change in the number of young produced. The Big Dry caused widespread declines in the floodplain avifauna. Despite the drought being broken by two years of well‐above‐average rainfall and subsequent near‐average rainfall, most species showed low resilience and there was little indication that overall breeding had increased. The effects of drought appeared to be pervasive for much of the floodplain avifauna, regardless of species traits (species body mass, fecundity, mobility or diet). Ecosystems such as these are likely to require active management and restoration, including reinstatement of natural flooding regimes, to improve ecological condition, to enhance resistance and resilience to extreme climate events. This article is protected by copyright. All rights reserved.
       
  • Differential contribution of demographic rate synchrony to population
           synchrony in barn swallows
    • Abstract: 1.Populations of many species show temporally synchronous dynamics over some range, mostly caused by spatial autocorrelation of the environment that affects demographic rates. Synchronous fluctuation of a demographic rate is a necessary, but not sufficient condition for population synchrony because population growth is differentially sensitive to variation in demographic rates. Little is known about the relative effects of demographic rates to population synchrony, because it is rare that all demographic rates from several populations are known. 2.We develop a hierarchical integrated population model with which all relevant demographic rates from all study populations can be estimated and apply it to demographic data of barn swallows Hirundo rustica from 9 sites that were between 19 and 224 km apart from each other. We decompose the variation of the population growth and of the demographic rates (apparent survival, components of productivity, immigration) into global and local temporal components using random effects which allowed the estimation of synchrony of these rates. 3.The barn swallow populations fluctuated synchronously, but less so than most demographic rates. The highest synchrony showed the probability of double brooding, while fledging success was highly asynchronous. Apparent survival, immigration and total productivity achieved intermediate levels of synchrony. The growth of all populations was most sensitive to changes in immigration and adult apparent survival, and both of them contributed to the observed temporal variation of population growth rates. 4.Using a simulation model we show that immigration and apparent survival of juveniles and adults were able to induce population synchrony, but not components of local productivity due to their low population growth rate sensitivity. Immigrants are mostly first time breeders and consequently their number depends on productivity of neighbouring populations. Since total productivity was synchronized we conclude that it contributed to population synchrony in an indirect way through dispersing individuals which appear as immigrants at the local scale. 5.The hierarchical integrated population model is promising for achieving an improved mechanistic understanding of population synchrony. This article is protected by copyright. All rights reserved.
       
 
 
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