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  Subjects -> BIOLOGY (Total: 2974 journals)
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    - ZOOLOGY (136 journals)

ZOOLOGY (136 journals)                     

Showing 1 - 0 of 0 Journals sorted alphabetically
Acta Herpetologica     Open Access   (Followers: 5)
Acta Theriologica     Full-text available via subscription   (Followers: 6)
Acta Zoologica     Hybrid Journal   (Followers: 5)
Acta Zoologica Cracoviensia     Free   (Followers: 2)
Acta zoológica mexicana     Open Access  
Advances in Zoology and Botany     Open Access  
African Invertebrates     Open Access  
African Journal of Herpetology     Full-text available via subscription   (Followers: 3)
African Journal of Wildlife Research     Full-text available via subscription   (Followers: 3)
African Zoology     Hybrid Journal   (Followers: 6)
American Journal of Zoological Research     Open Access   (Followers: 1)
Animal Behaviour     Hybrid Journal   (Followers: 133)
Animal Biology     Hybrid Journal   (Followers: 8)
Animal Biology & Animal Husbandry     Open Access   (Followers: 4)
Animal Biotelemetry     Open Access   (Followers: 1)
Animal Genetics     Hybrid Journal   (Followers: 8)
Animal Migration     Open Access   (Followers: 1)
Animal Studies Journal     Open Access   (Followers: 4)
Annales Zoologici     Full-text available via subscription  
Annales Zoologici Fennici     Open Access  
Annals of Animal Science     Open Access   (Followers: 1)
Annals of the Ditsong National Museum of Natural History     Full-text available via subscription   (Followers: 3)
Annual Review of Animal Biosciences     Full-text available via subscription   (Followers: 5)
Anthrozoos : A Multidisciplinary Journal of The Interactions of People & Animals     Hybrid Journal   (Followers: 7)
Applied Animal Behaviour Science     Hybrid Journal   (Followers: 17)
Applied Entomology and Zoology     Partially Free   (Followers: 2)
Aquatic Mammals     Full-text available via subscription   (Followers: 8)
Aquatic Sciences     Hybrid Journal   (Followers: 12)
Arquivos de Ciências Veterinárias e Zoologia da UNIPAR     Open Access   (Followers: 1)
Arthropod Management Tests     Hybrid Journal   (Followers: 2)
Asian Journal of Animal and Veterinary Advances     Open Access   (Followers: 8)
Australian Journal of Zoology     Hybrid Journal  
Bangladesh Journal of Zoology     Open Access  
Bioacoustics : The International Journal of Animal Sound and its Recording     Partially Free   (Followers: 2)
Biodiversidade     Open Access  
Bird Study     Full-text available via subscription   (Followers: 25)
Brazilian Journal of Veterinary Research and Animal Science     Open Access   (Followers: 9)
British Birds     Full-text available via subscription   (Followers: 24)
Bulletin of the Museum of Comparative Zoology     Full-text available via subscription   (Followers: 2)
Canadian Journal of Animal Science     Full-text available via subscription   (Followers: 4)
Canadian Journal of Zoology     Full-text available via subscription   (Followers: 16)
Canadian Zooarchaeology / Zooarchéologie canadienne     Open Access  
Contributions to Zoology     Open Access   (Followers: 3)
Current Zoology     Full-text available via subscription  
Der Zoologische Garten     Full-text available via subscription   (Followers: 2)
Ecology of Freshwater Fish     Hybrid Journal   (Followers: 18)
European Journal of Taxonomy     Open Access   (Followers: 3)
Euscorpius     Open Access  
EvoDevo     Open Access   (Followers: 3)
Fish and Fisheries     Hybrid Journal   (Followers: 29)
Frontiers in Zoology     Open Access   (Followers: 7)
Graellsia     Open Access  
Herpetology Notes     Open Access   (Followers: 4)
Hystrix, the Italian Journal of Mammalogy     Open Access  
i-Perception     Open Access   (Followers: 3)
Iheringia. Série Zoologia     Open Access   (Followers: 1)
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: 1)
International Journal of Zoology     Open Access   (Followers: 2)
International Studies on Sparrows     Open Access  
International Zoo Yearbook     Hybrid Journal   (Followers: 3)
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: 3)
Journal of Animal Ecology     Hybrid Journal   (Followers: 60)
Journal of Animal Physiology and Animal Nutrition     Hybrid Journal   (Followers: 5)
Journal of Apicultural Science     Open Access   (Followers: 2)
Journal of Applied Animal Research     Hybrid Journal   (Followers: 3)
Journal of Basic & Applied Zoology : Physiology     Open Access   (Followers: 2)
Journal of Experimental Zoology Part A: Ecological Genetics and Physiology     Hybrid Journal   (Followers: 4)
Journal of Experimental Zoology Part B : Molecular and Developmental Evolution     Hybrid Journal   (Followers: 2)
Journal of Freshwater Ecology     Hybrid Journal   (Followers: 14)
Journal of Herpetology     Full-text available via subscription   (Followers: 11)
Journal of Morphology     Hybrid Journal   (Followers: 4)
Journal of Threatened Taxa     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: 35)
Journal of Zoo and Aquarium Research     Open Access   (Followers: 4)
Journal of Zoological Systematics and Evolutionary Research     Hybrid Journal   (Followers: 4)
Journal of Zoology     Hybrid Journal   (Followers: 22)
Laboratory Animals     Hybrid Journal   (Followers: 13)
Mammalia     Hybrid Journal   (Followers: 6)
Memorias de la Conferencia Interna en Medicina y Aprovechamiento de Fauna Silvestre, Exótica y no Convencional     Open Access  
Monographs of the Transvaal Museum     Full-text available via subscription  
Natural History Sciences     Hybrid Journal   (Followers: 1)
New Zealand Journal of Zoology     Hybrid Journal   (Followers: 4)
Papéis Avulsos de Zoologia     Open Access  
Parasite     Open Access   (Followers: 4)
Physiological and Biochemical Zoology     Full-text available via subscription   (Followers: 6)
Polish Journal of Entomology     Open Access   (Followers: 4)
Primate Biology     Open Access   (Followers: 1)
Protist Genomics     Open Access   (Followers: 1)
Redia : Journal of Zoology     Open Access   (Followers: 1)
Remote Sensing in Ecology and Conservation     Open Access   (Followers: 14)
Research in Zoology     Open Access   (Followers: 2)
Revista Brasileira de Reprodução Animal     Open Access  
Revista Brasileira de Zoologia     Open Access  
Revista de Biología Marina y Oceanografía     Open Access  
Revista de Educação Continuada em Medicina Veterinária e Zootecnia     Open Access  
Revista de Zoologia     Open Access   (Followers: 1)
Russian Journal of Herpetology     Full-text available via subscription   (Followers: 2)
Scientific Journal of Animal Science     Open Access   (Followers: 4)
Scientific Journal of Zoology     Open Access   (Followers: 3)
SHILAP Revista de Lepidopterologia     Open Access   (Followers: 2)
Skeletal Muscle     Open Access   (Followers: 2)
South American Journal of Herpetology     Full-text available via subscription   (Followers: 4)
Sri Lanka Journal of Aquatic Sciences     Open Access   (Followers: 1)
Travaux du Muséum National d’Histoire Naturelle “Grigore Antipa”     Open Access  
Tropical Zoology     Partially Free   (Followers: 2)
Turkish Journal of Zoology     Open Access  
University Journal of Zoology, Rajshahi University     Open Access  
Veterinária e Zootecnia     Open Access  
Waterbirds     Full-text available via subscription   (Followers: 9)
Wildlife Society Bulletin     Hybrid Journal   (Followers: 9)
World Rabbit Science     Full-text available via subscription  
Zoo Biology     Hybrid Journal   (Followers: 9)
ZooKeys     Open Access   (Followers: 5)
Zoologia (Curitiba)     Open Access   (Followers: 1)
Zoologica Poloniae : The Journal of Polish Zoological Society     Open Access   (Followers: 1)
Zoologica Scripta     Hybrid Journal   (Followers: 3)
Zoological Journal of the Linnean Society     Hybrid Journal   (Followers: 11)
Zoological Letters     Open Access  
Zoological Science     Full-text available via subscription   (Followers: 2)
Zoological Studies     Open Access   (Followers: 1)
Zoologische Mededelingen     Open Access  
Zoologischer Anzeiger - A Journal of Comparative Zoology     Hybrid Journal  
Zoologist (The)     Full-text available via subscription  
Zoology     Hybrid Journal   (Followers: 6)
Zoology and Ecology     Hybrid Journal   (Followers: 5)
Zoomorphology     Hybrid Journal   (Followers: 3)
Zoosystematics and Evolution - Mitteilungen Aus Dem Museum Fur Naturkunde Zu Berlin     Open Access   (Followers: 1)
Zootecnia     Open Access  

           

Journal Cover Journal of Animal Ecology
  [SJR: 3.359]   [H-I: 119]   [60 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  [1605 journals]
  • Nitrogen deposition cancels out exotic earthworm effects on plant-feeding
           nematode communities
    • Authors: Yuanhu Shao; Weixin Zhang, Nico Eisenhauer, Tao Liu, Yanmei Xiong, Chenfei Liang, Shenglei Fu
      Abstract: 1.The activity and spread of exotic earthworms often are spatially correlated with N deposition because both arise from human activities. Exotic earthworms, in turn, can also greatly affect soil abiotic and biotic properties, as well as related ecological processes. Previous studies showed, for example, that earthworms can counteract the detrimental effects of plant-feeding nematodes on plant growth. However, potential interactive effects of N deposition and exotic earthworms on ecosystems are poorly understood.2.We explored the changes in density of plant-feeding nematodes in response to the presence of exotic earthworms, and whether these changes are altered by elevated N deposition in a two-factorial field mesocosm experiment at the Heshan National Field Research Station of Forest Ecosystem, in southern China.3.Our results show that earthworm addition marginally significantly increased the density of exotic earthworms and significantly increased the mass of earthworm casts. The total density of plant-feeding nematodes was not significantly affected by exotic earthworms or N deposition. However, exotic earthworms tended to increase the density of plant-feeding nematode taxa that are less detrimental to plant growth (r-strategists), while they significantly reduced the density of more harmful plant-feeding nematodes (K-strategists). Importantly, these earthworm effects were restricted to the ambient N deposition treatment, and elevated N deposition cancelled out the earthworm effect. Although exotic earthworms and N deposition interactively altered foliar N:P ratio in the target tree species, this did not result in significant changes in shoot and root biomass in the short term.4.Overall, our study indicates that N deposition can cancel out exotic earthworm-induced reductions in the density of harmful plant-feeding nematodes. These results suggest that anthropogenic N deposition can alter biotic interactions between exotic and native soil organisms with potential implications for ecosystem functioning.This article is protected by copyright. All rights reserved.
      PubDate: 2017-02-21T22:50:25.213879-05:
      DOI: 10.1111/1365-2656.12660
       
  • Sex Differences and Allee Effects Shape the Dynamics of Sex-Structured
           Invasions
    • Authors: Allison K. Shaw; Hanna Kokko, Michael G. Neubert
      Abstract: SummaryThe rate at which a population grows and spreads can depend on individual behaviour and interactions with others. In many species with two sexes, males and females differ in key life history traits (e.g. growth, survival, dispersal), which can scale up to affect population rates of growth and spread. In sexually reproducing species, the mechanics of locating mates and reproducing successfully introduce further complications for predicting the invasion speed (spread rate), as both can change nonlinearly with density.Most models of population spread are based on one sex, or include limited aspects of sex differences. Here we ask whether and how the dynamics of finding mates interact with sex-specific life history traits to influence the rate of population spread.We present a hybrid approach for modelling invasions of populations with two sexes that links individual-level mating behaviour (in an individual-based model) to population-level dynamics (in an integrodifference equation model).We find that limiting the amount of time during which individuals can search for mates causes a demographic Allee effect which can slow, delay or even prevent an invasion. Furthermore, any sex-based asymmetries in life history or behaviour (skewed sex ratio, sex-biased dispersal, sex-specific mating behaviours) amplify these effects. In contrast, allowing individuals to mate more than once ameliorates these effects, enabling polygynandrous populations to invade under conditions where monogamously mating populations would fail to establish.We show that details of individuals’ mating behaviour can impact the rate of population spread. Based on our results, we propose a stricter definition of a mate-finding Allee effect, which is not met by the commonly used minimum mating function. Our modelling approach, which links individual and population-level dynamics in a single model, may be useful for exploring other aspects of individual behaviour that are thought to impact the rate of population spread.This article is protected by copyright. All rights reserved.
      PubDate: 2017-02-20T21:55:22.697351-05:
      DOI: 10.1111/1365-2656.12658
       
  • Caching reduces kleptoparasitism in a solitary, large felid
    • Authors: Guy A. Balme; Jennifer R. B. Miller, Ross T. Pitman, Luke T. B. Hunter
      Abstract: Food caching is a common strategy used by a diversity of animals, including carnivores, to store and/or secure food. Despite its prevalence, the drivers of caching behaviour, and its impacts on individuals, remain poorly understood, particularly for short-term food cachers.Leopards Panthera pardus exhibit a unique form of short-term food caching, regularly hoisting, storing, and consuming prey in trees. We explored the factors motivating such behaviour among leopards in the Sabi Sand Game Reserve, South Africa, associated with four not mutually exclusive hypotheses: food-perishability, consumption-time, resource-pulse, and kleptoparasitism-avoidance.Using data from 2,032 prey items killed by 104 leopards from 2013–2015, we built generalized linear mixed models to examine how hoisting behaviour, feeding time, and the likelihood of a kill being kleptoparasitised varied with leopard sex and age, prey size and vulnerability, vegetation, elevation, climate, and the short-term (immediate presence) and long-term (species density) risk posed by dominant competitors.Leopards hoisted 51% of kills. They were more likely to hoist kills of an intermediate size, outside of a resource pulse, and in response to the presence of some competitors. Hoisted kills were also fed on for longer than non-hoisted kills. At least 21% of kills were kleptoparasitised, mainly by spotted hyaenas Crocuta crocuta. Kills were more likely to be kleptoparasitised at lower temperatures and if prey were larger, not hoisted, and in areas where the risk of encountering hyaenas was greatest. Female leopards that suffered higher rates of kleptoparasitism exhibited lower annual reproductive success than females that lost fewer kills.Our results strongly support the kleptoparasitism-avoidance hypothesis and suggest hoisting is a key adaptation that enables leopards to coexist sympatrically with high densities of competitors. We further argue that leopards may select smaller-sized prey than predicted by optimal foraging theory, to balance trade-offs between kleptoparasitic losses and the energetic gains derived from killing larger prey.Although caching may provide the added benefits of delaying food perishability and enabling consumption over an extended period, the behaviour primarily appears to be a strategy for leopards, and possibly other short-term cachers, to reduce the risks of kleptoparasitism. This article is protected by copyright. All rights reserved.
      PubDate: 2017-02-19T20:50:27.643215-05:
      DOI: 10.1111/1365-2656.12654
       
  • Range shifting species reduce phylogenetic diversity in high latitude
           communities via competition
    • Authors: Robert Fitt; Lesley T. Lancaster
      Abstract: Under anthropogenic climate change, many species are expanding their ranges to higher latitudes and altitudes, resulting in novel species interactions. The consequences of these range shifts for native species, patterns of local biodiversity, and community structure in high latitude ecosystems are largely unknown but critical to understand in light of widespread poleward expansions by many warm-adapted generalists.Using niche modelling, phylogenetic methods, and field and laboratory studies, we investigated how colonisation of Scotland by a range expanding damselfly, Ischnura elegans, influences patterns of competition and niche shifts in native damselfly species, and changes in phylogenetic community structure.Colonization by I. elegans was associated with reduced population density and niche shifts in the resident species least related to I. elegans (Lestes sponsa), reflecting enhanced competition. Furthermore, communities colonized by I. elegans exhibited phylogenetic underdispersion, reflecting patterns of relatedness and competition.Our results provide a novel example of a potentially general mechanism whereby climate change-mediated range shifts can reduce phylogenetic diversity within high latitude communities, if colonising species are typically competitively superior to members of native communities that are least-closely-related to the coloniser.This article is protected by copyright. All rights reserved.
      PubDate: 2017-02-19T20:50:22.399318-05:
      DOI: 10.1111/1365-2656.12655
       
  • Population dynamics of wild rodents induce stochastic fadeouts of a
           zoonotic pathogen
    • Authors: Giorgio Guzzetta; Valentina Tagliapietra, Sarah E. Perkins, Heidi C. Hauffe, Piero Poletti, Stefano Merler, Annapaola Rizzoli
      Abstract: Stochastic processes play an important role in the infectious disease dynamics of wildlife, especially in species subject to large population oscillations.Here we study the case of a free ranging population of yellow-necked mice (Apodemus flavicollis) in northern Italy, where circulation of Dobrava-Belgrade hantavirus (DOBV) has been detected intermittently since 2001, until an outbreak emerged in 2010.We analyzed the transmission dynamics of the recent outbreak using a computational model that accounts for seasonal changes of the host population and territorial behavior. Model parameters were informed by capture-mark-recapture data collected over 14 years and longitudinal seroprevalence data from 2010 to 2013.The intermittent observation of DOBV before 2010 can be interpreted as repeated stochastic fadeouts after multiple introductions of infectious rodents migrating from neighboring areas. We estimated that only 20% of introductions in a naïve host population results in sustained transmission after two years, despite an effective reproduction number well above the epidemic threshold (mean 4.5, 95% credible intervals, CI: 0.65-15.8). Following the 2010 outbreak, DOBV has become endemic in the study area, but we predict a constant probability of about 4.7% per year that infection dies out, following large population drops in winter. In the absence of stochastic fadeout, viral prevalence is predicted to continue its growth to an oscillating equilibrium around a value of 24% (95% CI: 3-57%).We presented an example of invasion dynamics of a zoonotic virus where stochastic fadeout have played a major role and may induce future extinction of the endemic infection. This article is protected by copyright. All rights reserved.
      PubDate: 2017-02-19T20:45:23.095352-05:
      DOI: 10.1111/1365-2656.12653
       
  • Life-history strategy determines constraints on immune function
    • Authors: Benjamin J. Parker; Seth M. Barribeau, Alice M. Laughton, Lynn H. Griffin, Nicole M. Gerardo
      Abstract: 1)Determining the factors governing investment in immunity is critical for understanding host-pathogen ecological and evolutionary dynamics. Studies often consider disease resistance in the context of life-history theory, with the expectation that investment in immunity will be optimized in anticipation of disease risk. Immunity, however, is constrained by context-dependent fitness costs. How the costs of immunity vary across life-history strategies has yet to be considered.2)Pea aphids are typically unwinged but produce winged offspring in response to high population densities and deteriorating conditions. This is an example of polyphenism, a strategy used by many organisms to adjust to environmental cues. The goal of this study was to examine the relationship between the fitness costs of immunity, pathogen resistance, and the strength of an immune response across aphid morphs that differ in life-history strategy but are genetically identical.3)We measured fecundity of winged and unwinged aphids challenged with a heat-inactivated fungal pathogen, and found that immune costs are limited to winged aphids. We hypothesized that these costs reflect stronger investment in immunity in anticipation of higher disease risk, and that winged aphids would be more resistant due to a stronger immune response. However, producing wings is energetically expensive. This guided an alternative hypothesis—that investing resources into wings could lead to a reduced capacity to resist infection.4)We measured survival and pathogen load after live fungal infection, and we characterized the aphid immune response to fungi by measuring immune cell concentration and gene expression. We found that winged aphids are less resistant and mount a weaker immune response than unwinged aphids, demonstrating that winged aphids pay higher costs for a less effective immune response.5)Our results show that polyphenism is an understudied factor influencing the expression of immune costs. More generally, our work shows that in addition to disease resistance, the costs of immunity vary between individuals with different life-history strategies. We discuss the implications of these findings for understanding how organisms invest optimally in immunity in light of context-dependent constraints.This article is protected by copyright. All rights reserved.
      PubDate: 2017-02-17T01:40:24.372905-05:
      DOI: 10.1111/1365-2656.12657
       
  • Detecting signals of chronic shedding to explain pathogen persistence:
           Leptospira interrogans in California sea lions
    • Authors: M. G. Buhnerkempe; K. C. Prager, C. C. Strelioff, D. J. Greig, J. L. Laake, S. R. Melin, R. L. DeLong, F. M. D. Gulland, J. O. Lloyd-Smith
      Abstract: Identifying mechanisms driving pathogen persistence is a vital component of wildlife disease ecology and control. Asymptomatic, chronically infected individuals are an oft-cited potential reservoir of infection but demonstrations of the importance of chronic shedding to pathogen persistence at the population level remain scarce.Studying chronic shedding using commonly collected disease data is hampered by numerous challenges, including short-term surveillance that focuses on single epidemics and acutely ill individuals, the subtle dynamical influence of chronic shedding relative to more obvious epidemic drivers, and poor ability to differentiate between the effects of population prevalence of chronic shedding versus intensity and duration of chronic shedding in individuals.We use chronic shedding of Leptospira interrogans serovar Pomona in California sea lions (Zalophus californianus) as a case study to illustrate how these challenges can be addressed. Using leptospirosis-induced strands as a measure of disease incidence, we fit models with and without chronic shedding, and with different seasonal drivers, to determine the timescale over which chronic shedding is detectable and the interactions between chronic shedding and seasonal drivers needed to explain persistence and outbreak patterns.Chronic shedding can enable persistence of L. interrogans within the sea lion population. However, the importance of chronic shedding was only apparent when surveillance data included at least two outbreaks and the intervening inter-epidemic trough during which fadeout of transmission was most likely. Seasonal transmission, as opposed to seasonal recruitment of susceptibles, was the dominant driver of seasonality in this system, and both seasonal factors had limited impact on long-term pathogen persistence.We show that the temporal extent of surveillance data can have a dramatic impact on inferences about population processes, where the failure to identify both short- and long-term ecological drivers can have cascading impacts on understanding higher-order ecological phenomena, such as pathogen persistence.This article is protected by copyright. All rights reserved.
      PubDate: 2017-02-16T15:35:25.385545-05:
      DOI: 10.1111/1365-2656.12656
       
  • To graze or gorge: consistency and flexibility of individual foraging
           tactics in tits
    • Authors: Nicole D. Milligan; Reinder Radersma, Ella F. Cole, Ben C. Sheldon
      Abstract: An individual's foraging behaviour and time allocated to feeding have direct consequences for its fitness. Despite much research on population-level foraging decisions, few studies have investigated individual differences in fine-scale daily foraging patterns amongst wild animals.Here, we explore the consistency and plasticity of feeding tactics of individual great tits (Parus major) and blue tits (Cyanistes caeruleus), using a grid of 65 automated feeding stations in a 385-ha woodland, during three winters. We use a principal component analysis to describe individual variation in six feeding parameters and examine how these differences covary with dominance-linked attributes (species, age and sex), the personality trait ‘exploration behaviour’, distance to territory, and local competition intensity.Analysis of 933,086 feeder visits by 3,134 individuals revealed that the majority of variation in the timing of feeding was explained by two principal components. PC1 (‘binge-eating’), accounting for 38% of variation, captured temporal clustering of feeding, with high repeatability both within and between years (r range: 0.42 to 0.55). PC2 (‘transience’), accounting for 27% of variance, described how much individuals used feeders and was also repeatable (r: 0.34 to 0.62). While exhibiting consistent individual differences, birds also showed flexibility in foraging patterns, binge-eating less and using feeders more when they experienced greater local competition.Individuals in behaviourally dominant states (great tits, males and adults) binged more than subordinate birds (blue tits, females and juveniles) when their territories were distant from feeding stations. Moreover, great tits and males used feeders more than blue tits and females respectively, while birds feeding further from their territory used feeders less than those feeding closer. ‘Exploration behaviour’ was unrelated to both measures of daily foraging behaviour.This study presents some of the first evidence that birds use consistent alternative foraging tactics at a fine temporal scale. Individuals are consistent in their tactics, but also adjust their foraging behaviour with changes in local competition. Hence, studies of foraging behaviour should consider the extent to which such individual-level variability in foraging behaviour is under selection.This article is protected by copyright. All rights reserved.
      PubDate: 2017-02-13T02:00:27.973548-05:
      DOI: 10.1111/1365-2656.12651
       
  • Complex Inter-Kingdom interactions: Carnivorous plants affect growth of an
           aquatic vertebrate
    • Authors: Jon M. Davenport; Alex W. Riley
      Abstract: 1.Coexistence of organisms in nature is more likely when phenotypic similarities of individuals are reduced. Despite the lack of similarity, distantly related taxa still compete intensely for shared resources. No larger difference between organisms that share a common prey could exist than between carnivorous plants and animals. However, few studies have considered inter-Kingdom competition among carnivorous plants and animals.2.In order to evaluate interactions between a carnivorous plant (greater bladderwort, Utricularia vulgaris) and a vertebrate (bluegill, Lepomis macrochirus) on a shared prey (zooplankton), we conducted a mesocosm experiment. We deployed two levels of bladderwort presence (functional and crushed) and measured bluegill responses (survival and growth).3.Zooplankton abundance was reduced the greatest in bluegill and functional bladderworts treatments. Bluegill survival did not differ among treatments, but growth was greatest with crushed bladderwort. Thus bluegill growth was facilitated by reducing interference competition in the presence of crushed bladderwort. The facilitating effect was dampened, however, when functional bladderwort removed a shared prey.4.To our knowledge, this is one of the first studies to experimentally demonstrate interactions between a carnivorous plant and a fish. Our data suggests that carnivorous plants may actively promote or reduce animal co-occurrence from some ecosystems via facilitation or competition.This article is protected by copyright. All rights reserved.
      PubDate: 2017-02-13T02:00:22.43103-05:0
      DOI: 10.1111/1365-2656.12652
       
  • Functional and phylogenetic structure of island bird communities
    • Authors: Xingfeng Si; Marc W. Cadotte, Di Zeng, Andrés Baselga, Yuhao Zhao, Jiaqi Li, Yiru Wu, Siyu Wang, Ping Ding
      Abstract: 1. Biodiversity change in anthropogenically transformed habitats is often nonrandom, yet the nature and importance of the different mechanisms shaping community structure are unclear. Here, we extend the classic Theory of Island Biogeography (TIB) to account for nonrandom processes by incorporating species traits and phylogenetic relationships into a study of faunal relaxation following habitat loss and fragmentation.2. Two possible mechanisms can create nonrandom community patterns on fragment islands. First, small and isolated islands might consist of similar or closely related species because they are environmentally homogeneous or select for certain shared traits, such as dispersal ability. Alternatively, communities on small islands might contain more dissimilar or distantly related species than on large islands because limited space and resource availability result in greater competitive exclusion among species with high niche overlap.3. Breeding birds were surveyed on 36 islands and two mainland sites annually from 2010 to 2014 in the Thousand Island Lake region, China. We assessed community structure of breeding birds on these subtropical land-bridge islands by integrating species’ trait and evolutionary distances. We additionally analysed habitat heterogeneity and variance in size ratios to distinguish biotic and abiotic processes of community assembly.4. Results showed that functional-phylogenetic diversity increased with island area, and decreased with island isolation. Bird communities on the mainland were more diverse and generally less clustered than island bird communities and not different than randomly assembled communities. Bird communities on islands tend to be functionally similar and phylogenetically clustered, especially on small and isolated islands.5. The nonrandom decline in species diversity and change in bird community structure with island area and isolation, along with the relatively homogeneous habitats on small islands, support the environmental filtering hypothesis. Our study demonstrates the importance of integrating multiple forms of diversity for understanding the effects of habitat loss and fragmentation, and further reveals that TIB could be extended to community measures by moving beyond assumptions of species equivalency in colonisation rates and extinction susceptibilities.This article is protected by copyright. All rights reserved.
      PubDate: 2017-02-13T01:55:26.66437-05:0
      DOI: 10.1111/1365-2656.12650
       
  • Social and environmental factors affect tuberculosis related mortality in
           wild meerkats
    • Authors: Stuart Patterson; Julian A. Drewe, Dirk. U. Pfeiffer, Tim H. Clutton-Brock
      Abstract: 1.Tuberculosis (TB) is an important and widespread disease of wildlife, livestock, and humans worldwide, but long-term empirical datasets describing this condition are rare. A population of meerkats (Suricata suricatta) in South Africa's Kalahari Desert have been diagnosed with Mycobacterium suricattae, a novel strain of TB, causing fatal disease in this group-living species.2.This study aimed to find characteristics associated with clinical TB in meerkats. These characteristics could subsequently be used to identify “at risk” animals within a population, and target these individuals for control measures.3.We conducted a retrospective study based on a unique, long-term life history dataset of over 2000 individually-identified animals covering a 14-year period after the first confirmatory diagnosis of TB in this population in 2001. Individual- and group-level risk factors were analysed using time-dependent Cox regression to examine their potential influence on the time to development of end-stage TB.4.Cases of disease involved 144 individuals in 27 of 73 social groups, across 12 out of 14 years (an incidence rate of 3.78 cases/100 study years). At the individual level, increasing age had the greatest effect on risk of disease with a hazard ratio of 4.70 (95% CI: 1.92-11.53, p
      PubDate: 2017-02-10T07:10:28.79297-05:0
      DOI: 10.1111/1365-2656.12649
       
  • Habitat connectivity and local conditions shape taxonomic and functional
           diversity of arthropods on green roofs
    • Authors: S Braaker; M K Obrist, J Ghazoul, M Moretti
      Abstract: 1.Increasing development of urban environments creates high pressure on green spaces with potential negative impacts on biodiversity and ecosystem services. There is growing evidence that green roofs – rooftops covered with vegetation – can contribute mitigate the loss of urban green spaces by providing new habitats for numerous arthropod species.2.Whether green roofs can contribute to enhance taxonomic and functional diversity and increase connectivity across urbanized areas remains, however, largely unknown. Furthermore, only limited information is available on how environmental conditions shape green roof arthropod communities.3.We investigated the community composition of arthropods (Apidae, Curculionidae, Araneae and Carabidae) on 40 green roofs and 40 green sites at ground level in the city of Zurich, Switzerland. We assessed how the site's environmental variables (such as area, height, vegetation, substrate and connectivity among sites) affect species richness and functional diversity using generalized linear models. We used an extension of co-inertia analysis (RLQ) and fourth-corner analysis to highlight the mechanism underlying community assemblages across taxonomic groups on green roof and ground communities.4.Species richness was higher at ground-level sites, while no difference in functional diversity was found between green roofs and ground sites. Green roof arthropod diversity increased with higher connectivity and plant species richness, irrespective of substrate depth, height and area of green roofs. The species trait analysis reviewed the mechanisms related to the environmental predictors that shape the species assemblages of the different taxa at ground and roof sites.5.Our study shows the important contribution of green roofs in maintaining high functional diversity of arthropod communities across different taxonomic groups, despite their lower species richness compared to ground sites. Species communities on green roofs revealed to be characterized by specific trait assemblages. The study also provides details on the environmental conditions that influence arthropod diversity and gives new perspectives on how the design of green roofs can be improved to increase their ecological value. Furthermore, the study highlights the importance of integrating green roofs in planning policies which aim to enhance urban habitat connectivity.This article is protected by copyright. All rights reserved.
      PubDate: 2017-02-06T03:20:59.541301-05:
      DOI: 10.1111/1365-2656.12648
       
  • Organismal responses to habitat change: herbivore performance, climate,
           and leaf traits in regenerating tropical dry forests
    • Authors: Salvatore J. Agosta; Catherine M. Hulshof, Ethan G. Staats
      Abstract: 1.The ecological effects of large-scale climate change have received much attention, but the effects of the more acute form of climate change that results from local habitat alteration have been less explored. When forest is fragmented, cut, thinned, cleared or otherwise altered in structure, local climates and microclimates change. Such changes can affect herbivores both directly (e.g., through changes in body temperature) and indirectly (e.g., through changes in host plant traits).2.We advance an eco-physiological framework to understand the effects of changing forests on herbivorous insects. We hypothesize that if tropical forest caterpillars are climate and resource specialists, then they should have reduced performance outside of mature forest conditions.3.We tested this hypothesis with a field experiment contrasting the performance of Rothschildia lebeau (Saturniidae) caterpillars feeding on the host plant Casearia nitida (Salicaceae) in two different aged and structured tropical dry forests in Area de Conservación Guanacaste, Costa Rica.4.Compared to more mature closed-canopy forest, in younger secondary forest we found that: (1) ambient conditions were hotter, drier, and more variable; (2) caterpillar growth and development were reduced; and (3) leaves were tougher, thicker, and drier. Further, caterpillar growth and survival were negatively correlated with these leaf traits, suggesting indirect host-mediated effects of climate on herbivores.5.Based on the available evidence, and relative to mature forest, we conclude that reduced herbivore performance in young secondary forest could have been driven by changes in climate, leaf traits (which were likely climate induced), or both. However, additional studies will be needed to provide more direct evidence of cause-and-effect and to disentangle the relative influence of these factors on herbivore performance in this system.This article is protected by copyright. All rights reserved.
      PubDate: 2017-02-01T09:05:40.146632-05:
      DOI: 10.1111/1365-2656.12647
       
  • Phylogenetic composition of host plant communities drives plant-herbivore
           food web structure
    • Authors: M Volf; P Pyszko, T Abe, M Libra, N Kotásková, M Šigut, R Kumar, O Kaman, P T Butterill, J Šipoš, H Abe, H Fukushima, P Drozd, N Kamata, M Murakami, V Novotny
      Abstract: 1.Insects tend to feed on related hosts. The phylogenetic composition of host plant communities thus plays a prominent role in determining insect specialization, food web structure, and diversity. Previous studies showed a high preference of insect herbivores for congeneric and confamilial hosts suggesting that some levels of host plant relationships may play more prominent role that others.2.We aim to quantify the effects of host phylogeny on the structure of quantitative plant-herbivore food webs. Further, we identify specific patterns in three insect guilds with different life histories and discuss the role of host plant phylogeny in maintaining their diversity.3.We studied herbivore assemblages in three temperate forests in Japan and the Czech Republic. Sampling from a canopy crane, a cherry picker and felled trees allowed a complete census of plant-herbivore interactions within three 0.1 ha plots for leaf chewing larvae, miners, and gallers. We analyzed the effects of host phylogeny by comparing the observed food webs with randomized models of host selection.4.Larval leaf chewers exhibited high generality at all three sites, whereas gallers and miners were almost exclusively monophagous. Leaf chewer generality dropped rapidly when older host lineages (5-80 myr) were collated into a single lineage but only decreased slightly when the most closely related congeneric hosts were collated. This shows that leaf chewer generality has been maintained by feeding on confamilial hosts while only a few herbivores were shared between more distant plant lineages and, surprisingly, between some congeneric hosts. In contrast, miner and galler generality was maintained mainly by the terminal nodes of the host phylogeny and dropped immediately after collating congeneric hosts into single lineages.5.We show that not all levels of host plant phylogeny are equal in their effect on structuring plant-herbivore food webs. In the case of generalist guilds, it is the phylogeny of deeper plant lineages that drives the food web structure whereas the terminal relationships play minor roles. In contrast, the specialization and abundance of monophagous guilds is affected mainly by the terminal parts of the plant phylogeny and does not generally reflect deeper host phylogeny.This article is protected by copyright. All rights reserved.
      PubDate: 2017-02-01T09:01:12.788634-05:
      DOI: 10.1111/1365-2656.12646
       
  • Field manipulations of resources mediate the transition from intraspecific
           competition to facilitation
    • Authors: Karin Svanfeldt; Keyne Monro, Dustin J. Marshall
      Abstract: 1.Population density affects individual performance, though its effects are often mixed. For sessile species, increases in population density typically reduce performance. Still, cases of positive density dependence do occur in sessile systems and demand explanation. The stress gradient hypothesis (SGH) predicts that under stressful conditions, positive effects of facilitation may outweigh the negative effects of competition.2.While some elements of the SGH are well studied, its potential to explain intraspecific facilitation has received little attention. Further, there have been questions regarding whether the SGH holds if the stressor is a resource. Most studies of interactions between the environment and intraspecific facilitation have relied on natural environmental gradients; manipulative studies are much rarer.3.To test the effects of intraspecific density and resources, we manipulated resource availability over natural population densities for the marine bryozoan Watersipora subtorquata.4.We found negative effects of density on colony performance in low resource environments, but mainly positive density-dependence in high resource environments. By adding resources, competition effects were reduced and the positive effects of facilitation were revealed.5.Our results suggest that resource availability mediates the relative strength of competition and facilitation in our system. We also suggest that intraspecific facilitation is more common than may be appreciated and that environmental variation may mediate the balance between negative and positive density-dependence.This article is protected by copyright. All rights reserved.
      PubDate: 2017-02-01T08:57:16.439041-05:
      DOI: 10.1111/1365-2656.12644
       
  • Many Places Called Home: the Adaptive Value of Seasonal Adjustments in
           Range Fidelity
    • Authors: Alexandre Lafontaine; Pierre Drapeau, Daniel Fortin, Martin-Hugues St-Laurent
      Abstract: 1.The vast majority of animal species display range fidelity, a space-use behaviour enhancing familiarity with local habitat features. While the fitness benefits of this behaviour have been demonstrated in a variety of taxa, some species or populations rather display infidelity, displacing their home range over time. Others, such as many ungulate species, show seasonal adjustments in their range fidelity to accommodate changes in the dominance of limiting factors or in the distribution of resources.2.Few empirical studies have explored the adaptive value of seasonal adjustments in range fidelity. Using boreal populations of woodland caribou (Rangifer tarandus caribou) as a biological model, we evaluated how range fidelity impacted individual performance during two seasons where juvenile and adult survival are limited by different predation pressures3.Between 2004 and 2013, we monitored the survival, reproductive success, habitat selection and range fidelity of female caribou in the boreal forest of eastern Canada. Using resource selection functions, we assessed how seasonal range fidelity was linked to two fitness correlates: calf survival in summer and adult female survival in winter.4.Females displayed season-specific space use tactics: they selected previously used areas during calving and summer, but tended to shift their winter range from one year to the next. During calving and summer, range fidelity yielded relatively high fitness benefits, as females that did not lose their calf displayed stronger fidelity than females that did. In winter, however, adult survival was negatively linked to range fidelity, as females that survived selected areas further away from their seasonal range of the previous year than females that died.5.We provide one of the first evidences that making seasonal adjustments in range fidelity can be an adaptive behaviour influencing the spatial distribution of a threatened species. Assessing the seasonal nature of range fidelity tactics may improve our predictions of space use and associated fitness implications for species displaying this behaviour.This article is protected by copyright. All rights reserved.
      PubDate: 2017-02-01T08:57:08.248291-05:
      DOI: 10.1111/1365-2656.12645
       
  • Predators regulate prey species sorting and spatial distribution in
           microbial landscapes
    • Authors: George Livingston; Kayoko Fukumori, Diogo B. Provete, Masanobu Kawachi, Noriko Takamura, Mathew A. Leibold
      Abstract: 1.The role of predation in determining the metacommunity assembly model of prey communities is understudied relative to that of interspecific competition among prey. Previous work on metacommunity dynamics of competing species has shown that sorting by habitat patch type and spatial patterning can be affected by disturbances.2.Microcosms offer a useful model system to test the effect of multi-trophic interactions and disturbance on metacommunity dynamics. Here, we investigated the potential role of predators in enhancing or disrupting sorting and spatial pattern among prey in experimental landscapes.3.We exposed multi-trophic protist microcosm landscapes with one predator, two competing prey, two patch resource types, and localized dispersal to three disturbance regimes (none, low, and high). Then, we used variation partitioning and spatial clustering analysis to analyze the results.4.In contrast with previous experiments that did not manipulate predators, we found that patch type did not structure prey communities very well. Instead, we found that it was the distribution of the predator that most strongly predicted the composition of the prey community.5.The predator impacted species sorting by 1) preferentially consuming one prey, thereby acting as a strong local environmental driver, and by 2) indirectly magnifying the impact of patch food resources on the less preferred prey. The predator also enhanced spatial signal in the prey community because of its limited dispersal.6.Our results indicate that predators can strongly influence prey species sorting and spatial patterning in metacommunities in ways that would otherwise be attributed to stochastic effects, such as dispersal limitation or demographic drift. Therefore, whenever possible, predators should be explicitly included as separate explanatory factors in variation partitioning analyses.This article is protected by copyright. All rights reserved.
      PubDate: 2017-01-31T02:30:53.137562-05:
      DOI: 10.1111/1365-2656.12639
       
  • Hidden survival heterogeneity of three Common eider populations in
           response to climate fluctuations
    • Authors: L. Guéry; S. Descamps, R. Pradel, S. A. Hanssen, K. E. Erikstad, G.W. Gabrielsen, H. G. Gilchrist, J. Bêty
      Abstract: 1.Understanding how individuals and populations respond to fluctuations in climatic conditions is critical to explain and anticipate changes in ecological systems. Most such studies focus on climate impacts on single populations without considering inter- and intra-population heterogeneity. However, comparing geographically dispersed populations limits the risk of faulty generalizations and helps to improve ecological and demographic models.2.We aimed to determine whether differences in migration tactics among and within populations would induce inter- or intra-population heterogeneity in survival in relation to winter climate fluctuations. Our study species was the Common eider (Somateria mollissima), a marine duck with a circumpolar distribution, which is strongly affected by climatic conditions during several phases of its annual cycle.3.Capture-mark-recapture (CMR) data were collected in two arctic (northern Canada and Svalbard) and one subarctic (northern Norway) population over a period of 18, 15 and 29 years, respectively. These three populations have different migration tactics and experience different winter climatic conditions. Using multi-event and mixture modelling, we assessed the association between adult female eider survival and winter conditions as measured by the North Atlantic Oscillation index.4.We found that winter weather conditions affected survival of female eiders from each of these three populations. However, different mechanisms seemed to be involved. Survival of the two migrating arctic populations was impacted directly by changes in the NAO, whereas the subarctic resident population was affected by the NAO with time lags of two to three years. Moreover, we found evidence for intra-population heterogeneity in the survival response to the winter NAO in the Canadian eider population, where individuals migrate to distinct wintering areas.5.Our results illustrate how individuals and populations of the same species can vary in their responses to climate variation. We suspect that the found variation in survival response of birds to winter conditions is partly explained by differences in migration tactic. Detecting and accounting for inter- and intra-population heterogeneity will improve our predictions concerning the response of wildlife to global changes.This article is protected by copyright. All rights reserved.
      PubDate: 2017-01-26T23:35:44.514264-05:
      DOI: 10.1111/1365-2656.12643
       
  • Parasites and a host's sense of smell: reduced chemosensory performance of
           
    • Authors: Ebrahim Lari; Cameron P. Goater, David K. Cone, Greg G. Pyle
      Abstract: 1.Parasites residing within the central nervous system of their hosts have the potential to reduce various components of host performance, but such effects are rarely evaluated.2.We assessed the olfactory acuity of fathead minnows (Pimephales promelas) infected experimentally with the monogenean Dactylogyrus olfactorius, the adults of which live within the host's olfactory chambers.3.Olfactory acuity was compared between infected and uninfected hosts by assessing electro-olfactography (EOG) neural responses to chemical stimuli that indicate the presence of food (L-alanine) or the presence of conspecifics (taurocholic acid). We also compared differences in gross morphology of the olfactory epithelium in infected and uninfected minnows.4.Differences in EOG responses between infected and uninfected minnows to both cue types were non-significant at 30 d post-exposure. By days 60 and 90, coincident with a two times increase in parasite intensity in the olfactory chambers, the EOG responses of infected minnows were 70-90% lower than controls. When infected fish were treated with a parasiticide (Prazipro), olfactory acuity returned to control levels by day 7 post-treatment.5.The observed reduction in olfactory acuity is best explained by the reduced density of cilia covering the olfactory chambers of infected fish, or by the concomitant increase in the density of mucous cells that cover the olfactory chambers. These morphological changes are likely due to the direct effects of attachment and feeding by individual worms or by indirect effects associated with host responses. Our results show that infection of a commonly occurring monogenean in fathead minnows reduces olfactory acuity. Parasite-induced interference with olfactory performance may reduce a fish's ability to detect, or respond to, chemical cues originating from food, predators, competitors, or mates.This article is protected by copyright. All rights reserved.
      PubDate: 2017-01-26T23:35:40.363746-05:
      DOI: 10.1111/1365-2656.12642
       
  • Competitor phenology as a social cue in breeding site selection
    • Authors: Jelmer M. Samplonius; Christiaan Both
      Abstract: Predicting habitat quality is a major challenge for animals selecting a breeding patch, because it affects reproductive success. Breeding site selection may be based on previous experience, or on social information from the density and success of competitors with an earlier phenology.Variation in animal breeding phenology is often correlated with variation in habitat quality. Generally, animals breed earlier in high quality habitats that allow them to reach a nutritional threshold required for breeding earlier or avoid nest predation. In addition, habitat quality may affect phenological overlap between species and thereby interspecific competition. Therefore, we hypothesized that competitor breeding phenology can be used as social cue by settling migrants to locate high quality breeding sites.To test this hypothesis, we experimentally advanced and delayed hatching phenology of two resident tit species on the level of study plots and studied male and female settlement patterns of migratory pied flycatchers Ficedula hypoleuca. The manipulations were assigned at random in two consecutive years, and treatments were swapped between years in sites that were used in both years.In both years, males settled in equal numbers across treatments, but later arriving females avoided pairing with males in delayed phenology plots. Moreover, male pairing probability declined strongly with arrival date on the breeding grounds.Our results demonstrate that competitor phenology may be used to assess habitat quality by settling migrants, but we cannot pinpoint the exact mechanism (e.g. resource quality, predation pressure, or competition) that has given rise to this pattern.In addition, we show that opposing selection pressures for arrival timing may give rise to different social information availabilities between sexes. We discuss our findings in the context of climate warming, social information use, and the evolution of protandry in migratory animals.This article is protected by copyright. All rights reserved.
      PubDate: 2017-01-24T15:20:26.402074-05:
      DOI: 10.1111/1365-2656.12640
       
  • Land-use type and intensity differentially filter traits in above- and
           belowground arthropod communities
    • Authors: Klaus Birkhofer; Martin M. Gossner, Tim Diekötter, Claudia Drees, Olga Ferlian, Mark Maraun, Stefan Scheu, Wolfgang W. Weisser, Volkmar Wolters, Susanne Wurst, Andrey S. Zaitsev, Henrik G. Smith
      Abstract: 1.Along with the global decline of species richness goes a loss of ecological traits. Associated biotic homogenization of animal communities and narrowing of trait diversity threaten ecosystem functioning and human well-being. High management intensity is regarded as an important ecological filter, eliminating species that lack suitable adaptations. Belowground arthropods are assumed to be less sensitive to such effects than aboveground arthropods.2.Here, we compared the impact of management intensity between (grassland vs. forest) and within land-use types (local management intensity) on the trait diversity and composition in below- and aboveground arthropod communities.3.We used data on 722 arthropod species living above ground (Auchenorrhyncha and Heteroptera), primarily in soil (Chilopoda and Oribatida) or at the interface (Araneae and Carabidae).4.Our results show that trait diversity of arthropod communities is not primarily reduced by intense local land use, but is rather affected by differences between land-use types. Communities of Auchenorrhyncha and Chilopoda had significantly lower trait diversity in grassland habitats as compared to forests. Carabidae showed the opposite pattern with higher trait diversity in grasslands. Grasslands had a lower proportion of large Auchenorrhyncha and Carabidae individuals, whereas Chilopoda and Heteroptera individuals were larger in grasslands. Body size decreased with land-use intensity across taxa, but only in grasslands. The proportion of individuals with low mobility declined with land-use intensity in Araneae and Auchenorrhyncha, but increased in Chilopoda and grassland Heteroptera. The proportion of carnivorous individuals increased with land-use intensity in Heteroptera in forests and in Oribatida and Carabidae in grasslands.5.Our results suggest that gradients in management intensity across land-use types will not generally reduce trait diversity in multiple taxa, but will exert strong trait filtering within individual taxa. The observed patterns for trait filtering in individual taxa are not related to major classifications into above- and belowground species. Instead, ecologically different taxa resembled each other in their trait diversity and compositional responses to land-use differences. These previously undescribed patterns offer an opportunity to develop management strategies for the conservation of trait diversity across taxonomic groups in permanent grassland and forest habitats.This article is protected by copyright. All rights reserved.
      PubDate: 2017-01-24T15:20:23.543852-05:
      DOI: 10.1111/1365-2656.12641
       
  • Reproductive success is driven by local site fidelity despite stronger
           specialisation by individuals for large scale habitat preference
    • Authors: Samantha Clare Patrick; Henri Weimerskirch
      Abstract: 1.There is widespread evidence that within populations, specialists and generalists can coexist and this is particularly prevalent in marine ecosystems, where foraging specialisations are evident.2.While individuals may limit niche overlap by consistently foraging in specific areas, site fidelity may also emerge as an artefact of habitat choice but both drivers and fitness consequences of site fidelity are poorly understood.3.Here we examine an individual metric of site and habitat fidelity, using tracking data collected over 11 years for black-browed albatrosses (Thalassarche melanophris). Fidelity was calculated as the similarity between pairs of foraging zones, quantifying measures for within and between years. Foraging areas were identified using area restricted search, defined as periods during which birds decrease speed and increase turning.4.Our results demonstrate that birds were considerably more specialised in the habitat in which they forage than the exact location they use within years, and there was a similar pattern between years. However, despite this, it was site fidelity that explained reproductive success. Within a single year, females which were more faithful to a specific location had higher reproductive success than non-specialists and between years there was tendency for both sexes.5.Our results suggest that black-browed albatrosses are highly faithful in their foraging habitat but it is rather site fidelity that is more clearly associated with reproductive success.This article is protected by copyright. All rights reserved.
      PubDate: 2017-01-24T11:35:30.0184-05:00
      DOI: 10.1111/1365-2656.12636
       
  • Metabolic theory predicts animal self-thinning
    • Authors: Tomas Jonsson
      Abstract: 1.The Metabolic Theory of Ecology (MTE) predicts observed patterns in ecology based on metabolic rates of individuals. The theory is influential but also criticized for a lack of firm empirical evidence confirming MTE's quantitative predictions of processes, e.g. outcome of competition, at population or community level.2.Self-thinning is a well-known population level phenomenon among plants, but a much less studied phenomenon in animal populations and no consensus exists on what a universal thinning slope for animal populations might be, or if it exists.3.The goal of this study was to use animal self-thinning as a tool to test population-level predictions from MTE, by analyzing (i) if self-thinning can be induced in populations of house crickets (Acheta domesticus) and (ii) if the resulting thinning trajectories can be predicted from metabolic theory, using estimates of the species-specific metabolic rate of A. domesticus4.I performed a laboratory study where the growth of A. domesticus was followed, from hatching until emergence as adults, in 71 cohorts of five different starting densities.5.96% of all cohorts in the three highest starting densities showed evidence of self-thinning, with estimated thinning slopes in general being remarkably close to that expected under metabolic constraints: A cross-sectional analysis of all data showing evidence of self-thinning produced an OLS slope of -1.11, exactly that predicted from specific metabolic allometry of Acheta domesticus. This result is furthermore supported by longitudinal analyses, allowing for independent responses within cohorts, producing a mean OLS slope across cohorts of -1.13 and a fixed effect LMEM slope of -1.09. Sensitivity analysis showed that these results are robust to how the criterion for on-going self-thinning was defined. Finally, also as predicted by metabolic theory, temperature had a negative effect on the thinning intercept, producing an estimate of the activation energy identical to that suggested by MTE.6.This study demonstrates a direct link between the metabolic rate of individuals and a population-level ecological process and as such provides strong support for research that aims to integrate body mass, via its effect on metabolism, consumption and competition, into models of populations and communities.This article is protected by copyright. All rights reserved.
      PubDate: 2017-01-19T09:00:35.151354-05:
      DOI: 10.1111/1365-2656.12638
       
  • Size structuring and allometric scaling relationships in coral reef fishes
    • Authors: Jillian C. Dunic; Julia K. Baum
      Abstract: Temperate marine fish communities are often size structured, with predators consuming increasingly larger prey and feeding at higher trophic levels as they grow. Gape limitation and ontogenetic diet shifts are key mechanisms by which size structuring arises in these communities. Little is known, however, about size structuring in coral reef fishes.Here, we aimed to advance understanding of size structuring in coral reef food webs by examining the evidence for these mechanisms in two groups of reef predators. Given the diversity of feeding modes amongst coral reef fishes, we also compared gape size—body size allometric relationships across functional groups to determine if they are reliable indicators of size structuring.We used gut content analysis and quantile regressions of predator size—prey size relationships to test for evidence of gape limitation and ontogenetic niche shifts in reef piscivores (n=13 species) and benthic invertivores (n=3 species). We then estimated gape size—body size allometric scaling coefficients for 21 different species from four functional groups, including herbivores/detritivores, which are not expected to be gape-limited.We found evidence of both mechanisms for size structuring in coral reef piscivores, with maximum prey size scaling positively with predator body size, and ontogenetic diet shifts including prey type and expansion of prey size. There was, however, little evidence of size structuring in benthic invertivores. Across species and functional groups, absolute and relative gape sizes were largest in piscivores as expected, but gape size—body size scaling relationships were not indicative of size structuring. Instead, relative gape sizes and mouth morphologies may be better indicators.Our results provide evidence that coral reef piscivores are size-structured, and that gape limitation and ontogenetic niche shifts are the mechanisms from which this structure arises. Although gape allometry was not indicative of size structuring, it may have implications for ecosystem function: positively allometric gape size—body size scaling relationships in herbivores/detritivores suggests that loss of large-bodied individuals of these species will have a disproportionately negative impact on reef grazing pressure.This article is protected by copyright. All rights reserved.
      PubDate: 2017-01-18T14:50:22.832989-05:
      DOI: 10.1111/1365-2656.12637
       
  • Low migratory connectivity is common in long-distance migrant birds
    • Authors: Tom Finch; Simon Butler, Aldina Franco, Will Cresswell
      Abstract: 1.Estimating how much long-distance migrant populations spread out and mix during the non-breeding season (migratory connectivity) is essential for understanding and predicting population dynamics in the face of global change.2.We quantify variation in population spread and inter-population mixing in long-distance, terrestrial migrant land-bird populations (712 individuals from 98 populations of 45 species, from tagging studies in the Neotropic and Afro-Palearctic flyways). We evaluate the Mantel test as a metric of migratory connectivity, and explore the extent to which variance in population spread can be explained simply by geography.3.The mean distance between two individuals from the same population during the non-breeding season was 743 km, covering 10–20% of the maximum width of Africa / South America. Individuals from different breeding populations tended to mix during the non-breeding season, though spatial segregation was maintained in species with relatively large non-breeding ranges (and, to a lesser extent, those with low population-level spread). A substantial amount of between-population variation in population spread was predicted simply by geography, with populations using non-breeding zones with limited land availability (e.g. Central America compared to South America) showing lower population spread.4.The high levels of population spread suggest that deterministic migration tactics are not generally adaptive; this makes sense in the context of the recent evolution of the systems, and the spatial and temporal unpredictability of non-breeding habitat.5.The conservation implications of generally low connectivity are that the loss (or protection) of any non-breeding site will have a diffuse but widespread effect on many breeding populations. Although low connectivity should engender population resilience to shifts in habitat (e.g. due to climate change), we suggest it may increase susceptibility to habitat loss. We hypothesise that because a migrant species cannot adapt to both simultaneously, migrants generally may be more susceptible to population declines in the face of concurrent anthropogenic habitat and climate change.This article is protected by copyright. All rights reserved.
      PubDate: 2017-01-16T22:55:23.906342-05:
      DOI: 10.1111/1365-2656.12635
       
  • Warmer temperatures reduce the influence of an important keystone predator
    • Authors: Chiara Bonaviri; Michael Graham, Paola Gianguzza, Nick T. Shears
      Abstract: Predator-prey interactions may be strongly influenced by temperature variations in marine ecosystems. Consequently, climate change may alter the importance of predators with repercussions for ecosystem functioning and structure.In North-eastern Pacific kelp forests, the starfish Pycnopodia helianthoides is known to be an important predator of the purple sea urchin Strongylocentrotus purpuratus. Here we investigated the influence of water temperature on this predator-prey interaction by: (1) assessing the spatial distribution and temporal dynamics of both species across a temperature gradient in the northern Channel Islands, California, and (2) investigating how the feeding rate of P. helianthoides on S. purpuratus is affected by temperature in laboratory tests.On average, at sites where mean annual temperatures were 16°C (equivalent to summer temperatures at sites where P. helianthoides were rare) reduced predation rates regardless of predator and prey sizes, although larger sea urchins were consumed only by large starfishes.These results clearly demonstrate that the effect of P. helianthoides on S. purpuratus is strongly mediated by temperature, and that the local abundance and predation rate of P. helianthoides on sea urchins will likely decrease with future warming. A reduction in top-down control on sea urchins, combined with other expected impacts of climate change on kelp, poses significant risks for the persistence of kelp forests in the future.This article is protected by copyright. All rights reserved.
      PubDate: 2017-01-11T07:50:58.03687-05:0
      DOI: 10.1111/1365-2656.12634
       
  • The changing contribution of top-down and bottom-up limitation of
           mesopredators during 220 years of land use and climate change
    • Authors: Marianne Pasanen-Mortensen; Bodil Elmhagen, Harto Lindén, Roger Bergström, Märtha Wallgren, Ype der Velde, Sara A. O. Cousins
      Abstract: Apex predators may buffer bottom-up driven ecosystem change, as top-down suppression may dampen herbivore and mesopredator responses to increased resource availability. However, theory suggests that for this buffering capacity to be realized, the equilibrium abundance of apex predators must increase. This raises the question: will apex predators maintain herbivore/mesopredator limitation, if bottom-up change relaxes resource constraints?Here, we explore changes in mesopredator (red fox Vulpes vulpes) abundance over 220 years in response to eradication and recovery of an apex predator (Eurasian lynx Lynx lynx), and changes in land use and climate which are linked to resource availability.A three-step approach was used. First, recent data from Finland and Sweden were modelled to estimate linear effects of lynx density, land use and winter temperature on fox density. Second, lynx density, land use and winter temperature was estimated in a 22 650 km2 focal area in boreal and boreo-nemoral Sweden in the years 1830, 1920, 2010 and 2050. Third, the models and estimates were used to project historic and future fox densities in the focal area.Projected fox density was lowest in 1830 when lynx density was high, winters cold and the proportion of cropland low. Fox density peaked in 1920 due to lynx eradication, a mesopredator release boosted by favourable bottom-up changes - milder winters and cropland expansion. By 2010, lynx recolonization had reduced fox density, but it remained higher than in 1830, partly due to the bottom-up changes. Comparing 1830 to 2010, the contribution of top-down limitation decreased, while environment enrichment relaxed bottom-up limitation. Future scenarios indicated that by 2050, lynx density would have to increase by 79% to compensate for a projected climate driven increase in fox density.We highlight that although top-down limitation in theory can buffer bottom-up change, this requires compensatory changes in apex predator abundance. Hence apex predator recolonization/recovery to historical levels would not be sufficient to compensate for widespread changes in climate and land use, which have relaxed the resource constraints for many herbivores and mesopredators. Variation in bottom-up conditions may also contribute to context dependence in apex predator effects.This article is protected by copyright. All rights reserved.
      PubDate: 2017-01-11T07:50:49.680322-05:
      DOI: 10.1111/1365-2656.12633
       
  • The Physiological Costs of Prey Switching Reinforce Foraging
           Specialization
    • Authors: Oliver E. Hooker; Travis E. Van Leeuwen, Colin E. Adams
      Abstract: Sympatric speciation is thought to be strongly linked to resource specialization with alternative resource use acting as a fundamental agent driving divergence. However, sympatric speciation through niche expansion is dependent on foraging specialization being consistent over space and time.Standard metabolic rate is the minimal maintenance metabolic rate of an ectotherm in a post-absorptive and inactive state and can constitute a significant portion of an animal's energy budget; thus standard metabolic rate and growth rate are two measures frequently used as an indication of the physiological performance of individuals. Physiological adaptations to a specific diet may increase the efficiency with which it is utilized, but may have an increased cost associated with switching diets, which may result in a reduced SMR and growth rate.In this study we use the diet specialization often seen in polymorphic Arctic charr (Salvelinus alpinus) populations to study the effects of different prey on standard metabolic rate and growth rate as well as the effects that early prey specialization may have on the ability to process other prey types efficiently.We found a significant effect of prey type on standard metabolic rate and growth rate. Furthermore, we found evidence of diet specialization with all fish maintaining a standard metabolic rate and growth rate lower than expected when fed on a diet different to which they were raised, possibly due to a maladaptation in digestion of alternative prey items.Our results show that early diet specialization may be reinforced by the elevated costs of prey switching thus promoting the process of resource specialization during the incipient stages of sympatric divergence.This article is protected by copyright. All rights reserved.
      PubDate: 2017-01-11T07:40:52.568364-05:
      DOI: 10.1111/1365-2656.12632
       
  • Intrapopulation variability in the timing of ontogenetic habitat shifts in
           sea turtles revealed using δ15N values from bone growth rings
    • Authors: Calandra N. Turner Tomaszewicz; Jeffrey A. Seminoff, S. Hoyt Peckham, Larisa Avens, Carolyn M. Kurle
      Abstract: Determining location and timing of ontogenetic shifts in the habitat use of highly migratory species, along with possible intrapopulation variation in these shifts, is essential for understanding mechanisms driving alternate life histories and assessing overall population trends. Measuring variations in multi-year habitat-use patterns is especially difficult for remote oceanic species.To investigate the potential for differential habitat use among migratory marine vertebrates, we measured the naturally occurring stable nitrogen isotope (δ15N) patterns that differentiate distinct ocean regions to create a ‘regional isotope characterization’, analysed the δ15N values from annual bone growth layer rings from dead-stranded animals, and then combined the bone and regional isotope data to track individual animal movement patterns over multiple years.We used humeri from juvenile North Pacific loggerhead turtles (Caretta caretta), animals that undergo long migrations across the North Pacific Ocean (NPO), using multiple discrete regions as they develop to adulthood. Typical of many migratory marine species, ontogenetic changes in habitat use throughout their decades-long juvenile stage is poorly understood, but each potential habitat has unique foraging opportunities and spatially explicit natural and anthropogenic threats that could affect key life-history parameters.We found a bimodal size/age distribution in the timing that juveniles underwent an ontogenetic habitat shift from the oceanic central North Pacific (CNP) to the neritic east Pacific region near the Baja California Peninsula (BCP) (42·7 ± 7·2 vs. 68·3 ± 3·4 cm carapace length, 7·5 ± 2·7 vs. 15·6 ± 1·7 years). Important to the survival of this population, these disparate habitats differ considerably in their food availability, energy requirements and threats, and these differences can influence life-history parameters such as growth, survival and future fecundity. This is the first evidence of alternative ontogenetic shifts and habitat-use patterns for juveniles foraging in the eastern NPO.We combine two techniques, skeletochronology and stable isotope analysis, to reconstruct multi-year habitat-use patterns of a remote migratory species, linked to estimated ages and body sizes of individuals, to reveal variable ontogeny during the juvenile life stage that could drive alternate life histories and that has the potential to illuminate the migration patterns for other species with accretionary tissues.This article combines skeletochronology with stable isotope analysis of annual bone growth layers to assess the variability in the size/age at which endangered juvenile North Pacific loggerhead sea turtles undergo an ontogenetic habitat shift between two disparate developmental foraging habitats, one of which is a sink habitat.
      PubDate: 2017-01-11T06:25:27.666435-05:
      DOI: 10.1111/1365-2656.12618
       
  • Honey buzzards don't always make a beeline
    • Authors: Jason W. Chapman
      Pages: 173 - 175
      Abstract: (a) European honey buzzards breeding in Western Europe primarily use soaring flight to make annual long-range migrations via the Strait of Gibraltar to winter in West Africa; this adult male was photographed on migration near Gibraltar. Photo: Javier Elloriaga. (b) Autumn migration routes of 12 satellite tagged adult European honey buzzards (colour-coded lines); compared with the shortest possible straight-line routes (dashed lines), most routes involved substantial westerly detours in Africa. Adapted from Vansteelant et al. (2016). (c) In contrast, Montagu's harriers predominantly use flapping flight during their migrations; this adult male is carrying a satellite transmitter. Photo: Theo van Kooten. (d) Autumn migration routes of 34 satellite tagged adult Montagu's harriers; migratory tracks more closely approached straight-line routes, and typically involved longer sea crossings, than seen in European honey buzzards. Adapted from Trierweiler et al. ().In Focus: Vansteelant, W.M.G., Shamoun-Baranes, J., van Manen, W., van Diermen, J. & Bouten, W. (2017) Seasonal detours by soaring migrants shaped by wind regimes along the East Atlantic Flyway. Journal of Animal Ecology, 86, 179–191.Migratory birds often make substantial detours from the shortest possible route during their annual migrations, which may potentially increase the duration and energetic cost of their journeys. Vansteelant et al. () investigate repeated migrations of adult European honey buzzards between the Netherlands and sub-Saharan Africa, and find that they make large westerly detours in Africa on both the spring and autumn routes. These detours allow migrants to capitalise on more favourable winds further along the route, thus reducing energy expenditure. Lifelong tracking studies will allow researchers to identify how migration routes have evolved to exploit predictable atmospheric and oceanic circulation patterns.Predictable large-scale wind patterns may provide opportunities for birds to achieve fast and efficient migrations. This article highlights the recent discovery that migrating honey buzzards take large detours while crossing the Sahara to take advantage of favourable winds further along the route, and discusses the implications of these findings for other long-range migrants which are impacted by currents.
      PubDate: 2017-02-07T08:23:26.371597-05:
      DOI: 10.1111/1365-2656.12620
       
  • Bold perch live life in the fast lane
    • Authors: Bart Adriaenssens
      Pages: 176 - 178
      Abstract: A schematic summary showing the links between behaviour and life-history observed by Nakayama, Rapp & Arlinghaus in wild Eurasion perch (Perca fluviatilis). [Colour figure can be viewed at wileyonlinelibrary.com].In Focus: Nakayama, S., Rapp, T. & Arlinghaus, R. (2017) Fast–slow life history is correlated with individual differences in movements and prey selection in an aquatic predator in the wild. Journal of Animal Ecology, 86, 192–201.The pace-of-life syndrome hypothesis (POLS) suggests that individual behavioural variation co-evolves with life-history variation, causing individuals on a fast life-history trajectory to display more active or bold personalities than individuals following a slow trajectory. In the present study, Nakayama, Rapp & Arlinghaus () followed the detailed movement patterns of wild Eurasian perch using acoustic telemetry and studied their relationships with life-history traits inferred from scale samples. Consistent with POLS, individuals with greater reproductive effort changed more often between active and passive behavioural modes. Moreover, individuals growing fast as a juvenile stayed active longer and moved over greater distances when adult. This study shows compelling evidence for covariance between personality and pace-of-life in a natural population.Nakayama and colleagues (2017) studied wild Eurasion perch (Perca fluviatilis) and showed that: (1) Adult perch growing fast as juveniles moved greater distances and spent more time active. (2) Early maturing individuals with greater reproductive effort became active more often. (3) Individuals with a high reproductive effort consumed more prey from pelagic (fish) vs. littoral (macroinvertebrates) pathways.
      PubDate: 2017-02-07T08:23:28.449187-05:
      DOI: 10.1111/1365-2656.12628
       
  • The long-term population dynamics of common wasps in their native and
           invaded range
    • Authors: Philip J. Lester; John Haywood, Michael E. Archer, Chris R. Shortall
      First page: 337
      Abstract: Populations of introduced species are often thought to perform differently, or experience different population dynamics, in their introduced range compared to their native habitat. Differences between habitats in climate, competition or natural enemies may result in populations with varying density dependence and population dynamics.We examined the long-term population dynamics of the invasive common wasp, Vespula vulgaris, in its native range in England and its invaded range in New Zealand. We used 39 years of wasp density data from four sites in England, and 23 years of data from six sites in New Zealand. Wasp population time series was examined using partial rate correlation functions. Gompertz population models and multivariate autoregressive state-space (MARSS) models were fitted, incorporating climatic variation.Gompertz models successfully explained 59–66% of the variation in wasp abundance between years. Density dependence in wasp populations appeared to act similarly in both the native and invaded range, with wasp abundance in the previous year as the most important variable in predicting intrinsic rate of increase (r). No evidence of cyclic population dynamics was observed.Both the Gompertz and MARSS models highlighted the role of weather conditions in each country as significant predictors of annual wasp abundance. The temporal evolution of wasp populations at all sites was best modelled jointly using a single latent dynamic factor for local trends, with the inclusion of a latent spring weather covariate. That same parsimonious multivariate model structure was optimal in both the native and invaded range.Density dependence is overwhelmingly important in predicting wasp densities and ‘wasp years’ in both the native and invaded range. Spring weather conditions in both countries have a major influence, probably through their impact on wasp colony initiation and early development. The population dynamics in the native range and invaded range show no evidence of cyclic boom-and-bust dynamics. Invasive species may not exhibit different population dynamics despite considerable variation in abundances throughout their distribution.Common wasps can be abundant and damaging pests. This study shows that the year-to-year variation in wasp numbers is governed by similar factors in the native and introduced range. High numbers in ‘wasp years’ are due to a lower abundance of wasps in the previous year and ideal spring weather conditions.
      PubDate: 2017-01-17T19:00:01.642939-05:
      DOI: 10.1111/1365-2656.12622
       
  • Corrigendum
    • First page: 414
      PubDate: 2017-01-18T04:45:22.52792-05:0
      DOI: 10.1111/1365-2656.12631
       
  • Dynamic vs. static social networks in models of parasite transmission:
           Predicting Cryptosporidium spread in wild lemurs
    • Authors: Andrea Springer; Peter M. Kappeler, Charles L. Nunn
      Abstract: 1.Social networks provide an established tool to implement heterogeneous contact structures in epidemiological models. Dynamic temporal changes in contact structure and ranging behavior of wildlife may impact disease dynamics. A consensus has yet to emerge, however, concerning the conditions in which network dynamics impact model outcomes, as compared to static approximations that average contact rates over longer time periods. Furthermore, as many pathogens can be transmitted both environmentally and via close contact, it is important to investigate the relative influence of both transmission routes in real-world populations.2.Here, we use empirically derived networks from a population of wild primates, Verreaux's sifakas (Propithecus verreauxi), and simulated networks to investigate pathogen spread in dynamic versus static social networks.3.First, we constructed a susceptible-exposed-infected-recovered (SEIR) model of Cryptosporidium spread in wild Verreaux's sifakas. We incorporated social and environmental transmission routes and parameterized the model for two different climatic seasons. Second, we used simulated networks and greater variation in epidemiological parameters to investigate the conditions in which dynamic networks produce larger outbreak sizes than static networks.4.We found that average outbreak size of Cryptosporidium infections in sifakas was larger when the disease was introduced in the dry season than in the wet season, driven by an increase in home range overlap toward the end of the dry season. Regardless of season, dynamic networks always produced larger average outbreak sizes than static networks. Larger outbreaks in dynamic models based on simulated networks occurred especially when the probability of transmission and recovery were low. Variation in tie strength in the dynamic networks also had a major impact on outbreak size, while network modularity had a weaker influence than epidemiological parameters that determine transmission and recovery.5.Our study adds to emerging evidence that dynamic networks can change predictions of disease dynamics, especially if the disease shows low transmissibility and a long infectious period, and when environmental conditions lead to enhanced between-group contact after an infectious agent has been introduced.This article is protected by copyright. All rights reserved.
      PubDate: 2016-12-14T10:15:32.551642-05:
      DOI: 10.1111/1365-2656.12617
       
  • Genetic Allee effects and their interaction with ecological Allee effects
    • Authors: Meike J. Wittmann; Hanna Stuis, Dirk Metzler
      Abstract: 1.It is now widely accepted that genetic processes such as inbreeding depression and loss of genetic variation can increase the extinction risk of small populations. However, it is generally unclear whether extinction risk from genetic causes gradually increases with decreasing population size or whether there is a sharp transition around a specific threshold population size. In the ecological literature, such threshold phenomena are called “strong Allee effects” and they can arise for example from mate limitation in small populations.2.In this study, we aim to a) develop a meaningful notion of a “strong genetic Allee effect”, b) explore whether and under what conditions such an effect can arise from inbreeding depression due to recessive deleterious mutations, and c) quantify the interaction of potential genetic Allee effects with the well-known mate-finding Allee effect.3.We define a strong genetic Allee effect as a genetic process that causes a population's survival probability to be a sigmoid function of its initial size. The inflection point of this function defines the critical population size. To characterize survival-probability curves, we develop and analyze simple stochastic models for the ecology and genetics of small populations.4.Our results indicate that inbreeding depression can indeed cause a strong genetic Allee effect, but only if individuals carry sufficiently many deleterious mutations (lethal equivalents). Populations suffering from a genetic Allee effect often first grow, then decline as inbreeding depression sets in, and then potentially recover as deleterious mutations are purged. Critical population sizes of ecological and genetic Allee effects appear to be often additive, but even superadditive interactions are possible.5.Many published estimates for the number of lethal equivalents in birds and mammals fall in the parameter range where strong genetic Allee effects are expected. Unfortunately, extinction risk due to genetic Allee effects can easily be underestimated as populations with genetic problems often grow initially, but then crash later. Also interactions between ecological and genetic Allee effects can be strong and should not be neglected when assessing the viability of endangered or introduced populations.This article is protected by copyright. All rights reserved.
      PubDate: 2016-10-12T03:51:17.911272-05:
      DOI: 10.1111/1365-2656.12598
       
  • Seasonal detours by soaring migrants shaped by wind regimes along the East
           Atlantic Flyway
    • Authors: Wouter M. G. Vansteelant; Judy Shamoun-Baranes, Willem Manen, Jan Diermen, Willem Bouten
      First page: 179
      Abstract: Avian migrants often make substantial detours between their seasonal destinations. It is likely some species do this to make the most of predictable wind regimes along their respective flyways. We test this hypothesis by studying orientation behaviour of a long-distance soaring migrant in relation to prevailing winds along the East Atlantic Flyway.We tracked 62 migratory journeys of 12 adult European Honey Buzzards Pernis apivorus with GPS loggers. Hourly fixes were annotated with local wind vectors from a global atmospheric model to determine orientation behaviours with respect to the buzzards’ seasonal goal destinations. This enabled us to determine hot spots where buzzards overdrifted and overcompensated for side winds. We then determined whether winds along the buzzards’ detours differed from winds prevailing elsewhere in the flyway.Honey Buzzards cross western Africa using different routes in autumn and spring. In autumn, they overcompensated for westward winds to circumvent the Atlas Mountains on the eastern side and then overdrifted with south-westward winds while crossing the Sahara. In spring, however, they frequently overcompensated for eastward winds to initiate a westward detour at the start of their journey. They later overdrifted with side winds north-westward over the Sahel and north-eastward over the Sahara, avoiding adverse winds over the central Sahara.We conclude that Honey Buzzards make seasonal detours to utilize more supportive winds further en route and thereby expend less energy while crossing the desert. Lifelong tracking studies will be helpful to elucidate how honey buzzards and other migrants learn complex routes to exploit atmospheric circulation patterns from local to synoptic scales.Many migrating birds engage in seasonal detours during migration. The authors show how a Palearctic soaring migrant initiates a detour into a headwind at the start of spring migration in anticipation of tailwinds later on in its journey.
      PubDate: 2016-10-18T19:00:02.808224-05:
      DOI: 10.1111/1365-2656.12593
       
  • Fast-slow life history is correlated with individual differences in
           movements and prey selection in an aquatic predator in the wild
    • Authors: Shinnosuke Nakayama; Tobias Rapp, Robert Arlinghaus
      First page: 192
      Abstract: Fast and slow life histories are proposed to covary with consistent individual differences in behaviour, but little is known whether it holds in the wild, where individuals experience natural fluctuations of the environment.We investigated whether individual differences in behaviour, such as movement traits and prey selection, are linked to variation in life-history traits in Eurasian perch (Perca fluviatilis) in the wild.Using high-resolution acoustic telemetry, we collected the positional data of fish in a whole natural lake and estimated individual movement traits by fitting a 2-state correlated random walk model. Prey selection was inferred from stable isotope analysis using scale samples. Life-history traits were estimated by fitting a biphasic growth model to an individual growth trajectory back-calculated from scale samples.Life-history traits were correlated with behavioural traits such as movements and prey selection. Individuals with higher reproductive effort were found to switch more frequently between active and inactive modes and show greater reliance on prey from pelagic pathways (indicated by lower δ13C). Further, individuals with faster juvenile growth were found to stay active for a longer time during the adult stage.Our results demonstrate the link between individual behavioural differences and fast-slow life-history traits under ecologically relevant conditions.This article is protected by copyright. All rights reserved.
      PubDate: 2016-10-17T08:21:13.050584-05:
      DOI: 10.1111/1365-2656.12603
       
  • Analysing animal social network dynamics: the potential of stochastic
           actor-orientated models
    • Authors: David N. Fisher; Amiyaal Ilany, Matthew J. Silk, Tom Tregenza
      First page: 202
      Abstract: Animals are embedded in dynamically changing networks of relationships with conspecifics. These dynamic networks are fundamental aspects of their environment, creating selection on behaviours and other traits. However, most social network-based approaches in ecology are constrained to considering networks as static, despite several calls for such analyses to become more dynamic.There are a number of statistical analyses developed in the social sciences that are increasingly being applied to animal networks, of which stochastic actor-oriented models (SAOMs) are a principal example. SAOMs are a class of individual-based models designed to model transitions in networks between discrete time points, as influenced by network structure and covariates. It is not clear however how useful such techniques are to ecologists, and whether they are suited to animal social networks.We review the recent applications of SAOMs to animal networks, outlining findings and assessing the strengths and weaknesses of SAOMs when applied to animal rather than human networks. We go on to highlight the types of ecological and evolutionary processes that SAOMs can be used to study.SAOMs can include effects and covariates for individuals, dyads, and populations, which can be constant or variable. This allows for the examination of a wide range of questions of interest to ecologists. However, high-resolution data are required, meaning SAOMs will not be useable in all study systems. It remains unclear how robust SAOMs are to missing data and uncertainty around social relationships.Ultimately, we encourage the careful application of SAOMs in appropriate systems, with dynamic network analyses likely to prove highly informative. Researchers can then extend the basic method to tackle a range of existing questions in ecology and explore novel lines of questioning.This article is protected by copyright. All rights reserved.
      PubDate: 2016-12-22T07:10:38.693598-05:
      DOI: 10.1111/1365-2656.12630
       
  • Correlational selection on personality and social plasticity: morphology
           and social context determine behavioural effects on mating success
    • Authors: Pierre-Olivier Montiglio; Tina W Wey, Ann T Chang, Sean Fogarty, Andrew Sih
      First page: 213
      Abstract: 1.Despite a central line of research aimed at quantifying relationships between mating success and sexually dimorphic traits (e.g., ornaments), individual variation in sexually selected traits often explains only a modest portion of the variation in mating success.2.Another line of research suggests that a significant portion of the variation in mating success observed in animal populations could be explained by correlational selection, where the fitness advantage of a given trait depends on other components of an individual's phenotype and/or its environment. We tested the hypothesis that interactions between multiple traits within an individual (phenotype-dependence) or between an individual's phenotype and its social environment (context-dependence) can select for individual differences in behaviour (i.e., personality) and social plasticity.3.To quantify the importance of phenotype- and context-dependent selection on mating success, we repeatedly measured the behaviour, social environment, and mating success of about 300 male stream water striders, Aquarius remigis. Rather than explaining individual differences in long-term mating success, we instead quantified how the combination of a male's phenotype interacted with the immediate social context to explain variation in hour-by-hour mating decisions. We suggest that this analysis captures more of the mechanisms leading to differences in mating success.4.Males differed consistently in activity, aggressiveness, and social plasticity. The mating advantage of these behavioural traits depended on male morphology and varied with the number of rival males in the pool, suggesting mechanisms selecting for consistent differences in behaviour and social plasticity. Accounting for phenotype- and context-dependence improved the amount of variation in male mating success we explained statistically by 30 – 274%.5.Our analysis of the determinants of male mating success provides important insights into the evolutionary forces that shape phenotypic variation. In particular, our results suggest that sexual selection is likely to favour individual differences in behaviour, social plasticity (i.e. individuals adjusting their behaviour), niche preference (i.e. individuals dispersing to particular social conditions), or social niche construction (i.e. individuals modifying the social environment). The true effect of sexual traits can only be understood in interaction with the individual's phenotype and environment.This article is protected by copyright. All rights reserved.
      PubDate: 2016-11-18T07:30:24.708458-05:
      DOI: 10.1111/1365-2656.12610
       
  • Repeatability, heritability, and age-dependence in the aggressiveness
           reaction norms of a wild passerine bird
    • Authors: Yimen G. Araya-Ajoy; Niels J. Dingemanse
      First page: 227
      Abstract: 1.Labile characters allow individuals to flexibly adjust their phenotype to changes in environmental conditions. There is growing evidence that individuals can differ both in average expression of and level of plasticity in this type of character. Both of these aspects are studied in conjunction within a reaction norm framework.2.Theoreticians have investigated the factors promoting variation in reaction norm intercepts (average phenotype) and slopes (level of plasticity) of a key labile character: behaviour. A general prediction from their work is that selection will favour the evolution of repeatable individual variation in level of plasticity only under certain ecological conditions. While factors promoting individual repeatability of plasticity have thus been identified, empirical estimates of this phenomenon are largely lacking for wild populations.3.We assayed aggressiveness of individual male great tits (Parus major) twice during their egg-laying stage and twice during their egg-incubation stage to quantify each male's level of seasonal plasticity. This procedure was applied during six consecutive years; all males breeding in our plots during those years were assayed, resulting in repeated measures of individual reaction norms for any individual breeding in multiple years. We quantified among- and within-individual variation in reaction norm components, allowing us to estimate repeatability of seasonal plasticity. Using social pedigree information, we further partitioned reaction norm components into their additive genetic and permanent environmental counterparts.4.Cross-year individual repeatability for the intercepts (average aggressiveness) and slopes (level of seasonal plasticity) of the aggressiveness reaction norms were 0.574 and 0.516 respectively. The posterior modes of the estimates suggested modest heritabilities (h2=0.260 for intercepts; h2=0.266 for slopes) that were relatively uncertain. Males behaved more aggressively in areas with higher breeding densities, and became less aggressive and less plastic with increasing age; plasticity thus varied within individuals and was multidimensional in nature.5.This empirical study quantified cross-year individual repeatability, heritability, and age-related reversible plasticity in behaviour. Acknowledging such patterns of multi-level variation is important not only for testing behavioural ecology theory concerning the evolution of repeatable differences in behavioural plasticity but also for predicting how reversible plasticity may evolve in natural populations.This article is protected by copyright. All rights reserved.
      PubDate: 2016-12-14T10:15:27.632879-05:
      DOI: 10.1111/1365-2656.12621
       
  • Sex-dependent carry-over effects on timing of reproduction and fecundity
           of a migratory bird
    • Authors: Nicola Saino; Roberto Ambrosini, Manuela Caprioli, Andrea Romano, Maria Romano, Diego Rubolini, Chiara Scandolara, Felix Liechti
      First page: 239
      Abstract: 1.Life of many organisms flows as a sequence of annual cycles. Timing of cyclical events is shaped by natural selection also via the domino effects that any life-history stage has on the stages that follow. Such ‘carry-over effects’ have major consequences for evolutionary, ecological and demographic processes, but the causes that generate their individual-level variation, including the effect of sex, are poorly understood.2.We used light-level geolocators to study carry-over effects on the year-round life-cycle of the long-distance migratory barn swallow (Hirundo rustica) and sex-dependent variation in their strength.3.Correlation analyses showed that timing of breeding influenced departure time for autumn migration in females but not in males. In addition, strong, time-mediated carry-over effects of timing of departure from the wintering areas in sub-Saharan Africa for spring migration on timing of arrival to the breeding grounds in Italy and Switzerland operated in both sexes. However, carry-over effects of spring migration phenology on breeding date and seasonal fecundity were observed among females but not among males.4.We used partial least squares path modelling to unveil the complex carry-over effects of phenology during the non-breeding season in combination with the ecological conditions experienced by individual swallows in the wintering area, as gauged by Normalized Difference Vegetation Index values (NDVI), on breeding performance. Phenology during the non-breeding season combined with NDVI during wintering accounted for as much as 65-70% of variation in subsequent seasonal fecundity in females, while such carry-over effects on breeding success of males were weaker.5.Intense, sex-specific carry-over effects can have impacted on evolutionary processes, including sexual selection, and affected phenological response to climate change, causing the large population decline observed in this species.This article is protected by copyright. All rights reserved.
      PubDate: 2016-12-21T02:31:25.591484-05:
      DOI: 10.1111/1365-2656.12625
       
  • Temporal shifts and temperature sensitivity of avian spring migratory
           phenology: A phylogenetic meta-analysis
    • Authors: T Usui; S H M Butchart, A B Phillimore
      First page: 250
      Abstract: 1.There are wide reports of advances in the timing of spring migration of birds over time and in relation to rising temperatures, though phenological responses vary substantially within and among species. An understanding of the ecological, life-history and geographic variables that predict this intra- and inter-specific variation can guide our projections of how populations and species are likely to respond to future climate change.2.Here, we conduct phylogenetic meta-analyses addressing slope estimates of the timing of avian spring migration regressed on (i) year and (ii) temperature, representing a total of 413 species across five continents. We take into account slope estimation error and examine phylogenetic, ecological and geographic predictors of intra- and inter-specific variation.3.We confirm earlier findings that on average birds have significantly advanced their spring migration time by 2.1 days decade−1 and 1.2 days °C−1. We find that over time and in response to warmer spring conditions short-distance migrants have advanced spring migratory phenology by more than long-distance migrants. We also find that larger bodied species show greater advance over time compared to smaller bodied species. Our results did not reveal any evidence that interspecific variation in migration response is predictable on the basis of species’ habitat or diet.4.We detected a substantial phylogenetic signal in migration time in response to both year and temperature, suggesting that some of the shifts in migratory phenological response to climate are predictable on the basis of phylogeny. However, we estimate high levels of species and spatial variance relative to phylogenetic variance, which is consistent with plasticity in response to climate evolving fairly rapidly and being more influenced by adaptation to current local climate than by common descent.5.On average, avian spring migration times have advanced over time and as spring has become warmer. While we are able to identify predictors that explain some of the true among-species variation in response, substantial intra- and inter-specific variation in migratory response remains to be explained.This article is protected by copyright. All rights reserved.
      PubDate: 2016-11-18T11:45:21.644962-05:
      DOI: 10.1111/1365-2656.12612
       
  • Precipitation alters interactions in a grassland ecological community
    • Authors: Nicolas Deguines; Justin S. Brashares, Laura R. Prugh
      First page: 262
      Abstract: 1.Climate change is transforming precipitation regimes worldwide. Changes in precipitation regimes are known to have powerful effects on plant productivity, but the consequences of these shifts for the dynamics of ecological communities are poorly understood. This knowledge gap hinders our ability to anticipate and mitigate the impacts of climate change on biodiversity.2.Precipitation may affect fauna through direct effects on physiology, behavior or demography, through plant-mediated indirect effects, or by modifying interactions among species. In this paper, we examined the response of a semi-arid ecological community to a fivefold change in precipitation over seven years.3.We examined the effects of precipitation on the dynamics of a grassland ecosystem in central California from 2007 to 2013. We conducted vegetation surveys, pitfall trapping of invertebrates, visual surveys of lizards, and capture-mark-recapture surveys of rodents on 30 plots each year. We used structural equation modelling to evaluate the direct, indirect, and modifying effects of precipitation on plants, ants, beetles, orthopterans, kangaroo rats, ground squirrels, and lizards.4.We found pervasive effects of precipitation on the ecological community. Although precipitation increased plant biomass, direct effects on fauna were often stronger than plant-mediated effects. In addition, precipitation altered the sign or strength of consumer-resource and facilitative interactions among the faunal community such that negative or neutral interactions became positive or vice versa with increasing precipitation.5.These findings indicate that precipitation influences ecological communities in multiple ways beyond its recognized effects on primary productivity. Stochastic variation in precipitation may weaken the average strength of biotic interactions over time, thereby increasing ecosystem stability and resilience to climate change.This article is protected by copyright. All rights reserved.
      PubDate: 2016-11-27T04:05:22.854633-05:
      DOI: 10.1111/1365-2656.12614
       
  • Projected changes in prevailing winds for transatlantic migratory birds
           under global warming
    • Authors: Frank A. La Sorte; Daniel Fink
      First page: 273
      Abstract: 1.A number of terrestrial bird species that breed in North America cross the Atlantic Ocean during autumn migration when travelling to their non-breeding grounds in the Caribbean or South America. When conducting oceanic crossings, migratory birds tend to associate with mild or supportive winds, whose speed and direction may change under global warming. The implications of these changes for transoceanic migratory bird populations have not been addressed.2.We used occurrence information from eBird (1950 to 2015) to estimate the geographic location of population centres at a daily temporal resolution across the annual cycle for ten transatlantic migratory bird species. We used this information to estimate the location and timing of autumn migration within the transatlantic flyway. We estimated how prevailing winds are projected to change within the transatlantic flyway during this time using daily wind speed anomalies (1996-2005 and 2091-2100) from 29 Atmosphere-Ocean General Circulation Models implemented under CMIP5.3.Autumn transatlantic migrants have the potential to encounter strong westerly crosswinds early in their transatlantic journey at intermediate and especially high migration altitudes, strong headwinds at low and intermediate migration altitudes within the Caribbean that increase in strength as the season progresses, and weak tailwinds at intermediate and high migration altitudes east of the Caribbean. The CMIP5 simulations suggest that, during this century, the likelihood of autumn transatlantic migrants encountering strong westerly crosswinds will diminish.4.As global warming progresses, the need for species to compensate or drift under the influence of strong westerly crosswinds during the initial phase of their autumn transatlantic journey may be diminished. Existing strategies that promote headwind avoidance and tailwind assistance will likely remain valid. Thus, climate change may reduce time and energy requirements and the chance of mortality or vagrancy during a specific but likely critical portion of these species’ autumn migration journey.This article is protected by copyright. All rights reserved.
      PubDate: 2016-12-14T09:40:27.252953-05:
      DOI: 10.1111/1365-2656.12624
       
  • Climatic conditions produce contrasting influences on demographic traits
           in a long distance Arctic migrant
    • Authors: Ian R. Cleasby; Thomas W. Bodey, Freydis Vigfusdottir, Jenni L. McDonald, Graham McElwaine, Kerry Mackie, Kendrew Colhoun, Stuart Bearhop
      First page: 285
      Abstract: The manner in which patterns of variation and interactions among demographic rates contribute to population growth rate (λ) are key to understanding how animal populations will respond to changing climatic conditions.Migratory species are likely to be particularly sensitive to climatic conditions as they experience a range of different environments throughout their annual cycle. However, few studies have provided fully integrated demographic analyses of migratory populations in response to changing climatic conditions.Here, we employed integrated population models (IPM) to demonstrate that the environmental conditions experienced during a short, but critical period, play a central role in the demography of a long-distance migrant, the light-bellied Brent goose (Branta bernicla hrota).Female survival was positively associated with June North Atlantic Oscillation (NAO) values, whereas male survival was not. In contrast, breeding productivity was negatively associated with June NAO, suggesting a trade-off between female survival and reproductive success. Both adult female and adult male survival showed low temporal variation, whereas there was high temporal variation in recruitment and breeding productivity. In addition, while annual population growth was positively correlated with annual breeding productivity a sensitivity analysis revealed that population growth was most sensitive to changes in adult survival.Our results demonstrate that the environmental conditions experienced during a relatively short-time window at the start of the breeding season play a critical role in shaping the demography of a long-distant Arctic migrant. Crucially, different demographic rates responded in opposing directions to climatic variation, emphasizing the need for integrated analysis of multiple demographic traits when understanding population dynamics.This article is protected by copyright. All rights reserved.
      PubDate: 2016-12-14T10:21:05.687704-05:
      DOI: 10.1111/1365-2656.12623
       
  • Climatic conditions cause spatially dynamic polygyny thresholds in a large
           mammal
    • Authors: Jeffrey A. Manning; Philip D. McLoughlin
      First page: 296
      Abstract: 1.The polygyny threshold (PT) is a critical transition point in the sexual selection process for many organisms in natural populations, characterizing when females choose to mate with an already mated male over an unmated one to improve fitness. Understanding its causes and consequences is therefore of high interest. While both theoretical and empirical work suggest that the degree of polygyny within a species is plastic and a function of male inequality, the functional relationship between underlying availability of resources occupied by breeding males under variable climatic conditions and the dynamics of PTs across space and time has received less attention.2. Here, we use a standardized measure of male mating inequality as the culmination of female mate choices to analyze how spatially dynamic PTs in a naturally regulated feral horse (Equus ferus caballus) population emerge along a geographic gradient in a known, limiting resource (freshwater) each year from variable climatic conditions. PT distance from permanent freshwater increased with increasing precipitation during the breeding season of each year, suggesting a relationship between annual resource availability and female mate choice.3. The mechanism by which climatic conditions underpin the spatial dynamics of PTs was likely through precipitation providing ephemeral freshwater sources across the study area that effectively weakened the gradient in availability of permanent freshwater, thereby providing mating males that occupied home ranges far from permanent water with access to this limiting resource and enabling them to attract and retain females. Increased precipitation also coincided with a decreased proportion of males in the population that experienced sexual selection pressure attributed to female mate choice in relation to the acquisition and/or defense of freshwater sources.4. Climatic conditions caused spatial shifts in PTs annually along the geographic gradient in resource availability. Our findings reveal that such environmental gradients may either buffer or amplify impacts of climatic variation on selection pressure operating in natural populations, and emphasize the importance of integrating spatially explicit PTs with atmospheric fluctuations when predicting the effect of climatic change on selection processes within populations that occupy environmental gradients.This article is protected by copyright. All rights reserved.
      PubDate: 2016-11-15T06:11:01.965019-05:
      DOI: 10.1111/1365-2656.12608
       
  • Bottom-up and trait-mediated effects of resource quality on amphibian
           parasitism
    • Authors: Jeffrey P. Stephens; Karie A. Altman, Keith A. Berven, Scott D. Tiegs, Thomas R. Raffel
      First page: 305
      Abstract: Leaf litter subsidies are important resources for aquatic consumers like tadpoles and snails, causing bottom-up effects on wetland ecosystems. Recent studies have shown that variation in litter nutritional quality can be as important as litter quantity in driving these bottom-up effects. Resource subsidies likely also have indirect and trait-mediated effects on predation and parasitism, but these potential effects remain largely unexplored.We generated predictions for differential effects of litter nutrition and secondary polyphenolic compounds on tadpole (Lithobates sylvatica) exposure and susceptibility to Ribeiroia ondatrae, based on ecological stoichiometry and community-ecology theory. We predicted direct and indirect effects on key traits of the tadpole host (rates of growth, development and survival), the trematode parasite (production of the cercaria infective stages) and the parasite's snail intermediate host (growth and reproduction).To test these predictions, we conducted a large-scale mesocosm experiment using a natural gradient in the concentrations of nutrients (nitrogen) and toxic secondary compounds (polyphenolics) of nine leaf litter species. To differentiate between effects on exposure vs. susceptibility to infection, we included multiple infection experiments including one with constant per capita exposure.We found that increased litter nitrogen increased tadpole survival, and also increased cercaria production by the snail intermediate hosts, causing opposing effects on tadpole per capita exposure to trematode infection. Increased litter polyphenolics slowed tadpole development, leading to increased infection by increasing both their susceptibility to infection and the length of time they were exposed to parasites.Based on these results, recent shifts in forest composition towards more nitrogen-poor litter species should decrease trematode infection in tadpoles via density- and trait-mediated effects on the snail intermediate hosts. However, these shifts also involve increased abundance of litter species with high polyphenolic levels, which should increase trematode via trait-mediated effects on tadpoles. Future studies will be needed to determine the relative strength of these opposing effects in natural wetland communities.This study demonstrates how the theory of ecological stoichiometry can be used to successfully predict the outcomes of complex host–parasite interactions in aquatic ecosystems when the quality of basal resources is known.
      PubDate: 2016-12-27T19:00:02.500523-05:
      DOI: 10.1111/1365-2656.12613
       
  • A quantitative framework to estimate the relative importance of
           environment, spatial variation and patch connectivity in driving community
           composition
    • Authors: Viviane F. Monteiro; Paulo C. Paiva, Pedro R. Peres-Neto
      First page: 316
      Abstract: Perhaps the most widely used quantitative approach in metacommunity ecology is the estimation of the importance of local environment versus spatial structuring using the variation partitioning framework. Contrary to metapopulation models, however, current empirical studies of metacommunity structure using variation partitioning assume a space-for-dispersal substitution due to the lack of analytical frameworks that incorporate patch connectivity predictors of dispersal dynamics.Here, a method is presented that allows estimating the relative importance of environment, spatial variation and patch connectivity in driving community composition variation within metacommunities. The proposed approach is illustrated by a study designed to understand the factors driving the structure of a soft-bottom marine polychaete metacommunity.Using a standard variation partitioning scheme (i.e., where only environmental and spatial predictors are used), only about 13% of the variation in metacommunity structure was explained. With the connectivity set of predictors, the total amount of explained variation increased up to 51% of the variation.These results highlight the importance of considering predictors of patch connectivity rather than just spatial predictors. Given that information on connectivity can be estimated by commonly available data on species distributions for a number of taxa, the framework presented here can be readily applied to past studies as well, facilitating a more robust evaluation of the factors contributing to metacommunity structure. This article is protected by copyright. All rights reserved.
      PubDate: 2016-12-14T09:51:15.941524-05:
      DOI: 10.1111/1365-2656.12619
       
  • Experimentally reducing species abundance indirectly affects food web
           structure and robustness
    • Authors: Milton Barbosa; G. Wilson Fernandes, Owen T. Lewis, Rebecca J. Morris
      First page: 327
      Abstract: 1.Studies on the robustness of ecological communities suggest that the loss or reduction in abundance of individual species can lead to secondary and cascading extinctions. However, most such studies have been simulation-based analyses of the effect of primary extinction on food web structure.2.In a field experiment we tested the direct and indirect effects of reducing the abundance of a common species, focusing on the diverse and self-contained assemblage of arthropods associated with an abundant Brazilian shrub, Baccharis dracunculifolia D.C. (Asteraceae).3.Over a 5-month period we experimentally reduced the abundance of Baccharopelma dracunculifoliae (Sternorrhyncha: Psyllidae), the commonest galling species associated with B. dracunculifolia, in 15 replicate plots paired with 15 control plots. We investigated direct effects of the manipulation on parasitoids attacking B. dracunculifoliae, as well as indirect effects (mediated via a third species or through the environment) on ten other galler species and 50 associated parasitoid species.4.The experimental manipulation significantly increased parasitism on B. dracunculifoliae in the treatment plots, but did not significantly alter either the species richness or abundance of other galler species. Compared to control plots, food webs in manipulated plots had significantly lower values of weighted connectance, interaction evenness and robustness (measured as simulated tolerance to secondary extinction), even when B. dracunculifoliae was excluded from calculations.5.Parasitoid species were almost entirely specialised to individual galler species, so the observed effects of the manipulation on food web structure could not have propagated via the documented trophic links. Instead, they must have spread either through trophic links not included in the webs (e.g., shared predators) or non-trophically (e.g., through changes in habitat availability). Our results highlight that the inclusion of both trophic and non-trophic direct and indirect interactions is essential to understand the structure and dynamics of even apparently discrete ecological communities.This article is protected by copyright. All rights reserved.
      PubDate: 2016-12-21T02:35:26.723826-05:
      DOI: 10.1111/1365-2656.12626
       
  • Trait–demography relationships underlying small mammal population
           fluctuations
    • Authors: Koen J. van Benthem; Hannah Froy, Tim Coulson, Lowell L. Getz, Madan K. Oli, Arpat Ozgul
      First page: 348
      Abstract: 1.Large-scale fluctuations in abundance are a common feature of small mammal populations and have been the subject of extensive research. These demographic fluctuations are often associated with concurrent changes in the average body mass of individuals, sometimes referred to as the “Chitty effect”. Despite the long-standing recognition of this phenomenon, an empirical investigation of the underlying coupled dynamics of body mass and population growth has been lacking.2.Using long-term life-history data combined with a trait-based demographic approach, we examined the relationship between body mass and demography in a small mammal population that exhibits non-cyclic, large-scale fluctuations in abundance. We used data from the male segment of a 25-year study of the monogamous prairie vole, Microtus ochrogaster, in Illinois, USA. Specifically, we investigated how trait–demography relationships and trait distributions changed between different phases of population fluctuations, and the consequences of these changes for both trait and population dynamics.3.We observed phase-specific changes in male adult body mass distribution in this population of prairie voles. Our analyses revealed that these changes were driven by variation in ontogenetic growth, rather than selection acting on the trait. The resulting changes in body mass influenced most life-history processes, and these effects varied among phases of population fluctuation. However, these changes did not propagate to affect the population growth rate due to the small effect of body mass on vital rates, compared to the overall differences in vital rates between phases. The increase phase of the fluctuations was initiated by enhanced survival, particularly of juveniles, and fecundity whereas the decline phase was driven by an overall reduction in fecundity, survival and maturation rates.4.Our study provides empirical support, as well as a potential mechanism, underlying the observed trait changes accompanying population fluctuations. Body size dynamics and population fluctuations resulted from different life-history processes. Therefore, we conclude that body size dynamics in our population do not drive the observed population dynamics. This more in-depth understanding of different components of small mammal population fluctuations will help us to better identify the mechanistic drivers of this interesting phenomenon.This article is protected by copyright. All rights reserved.
      PubDate: 2016-12-21T02:45:25.663706-05:
      DOI: 10.1111/1365-2656.12627
       
  • Seal mothers expend more on offspring under favourable conditions and less
           when resources are limited
    • Authors: Clive R. McMahon; Robert G. Harcourt, Harry R. Burton, Owen Daniel, Mark A. Hindell
      First page: 359
      Abstract: 1.In mammals, maternal expenditure on offspring is a complex mix of several factors including the species’ mating system, offspring sex and the condition and age of the mother. While theory suggests that in polygynous species mothers should wean larger male offspring than females when resources and maternal conditions allow, the evidence for this remains equivocal.2.Southern elephant seals are highly dimorphic, polygynous capital breeders existing in an environment with highly variable resources and should therefore provide clear evidence to support the theoretical expectations of differential maternal expenditure in male and female pups.3.We quantified maternal size (mass and length) and pup size at birth and weaning for 342 elephant seal mothers at Macquarie Island. The study was conducted over 11 years of contrasting sea-ice and Southern Annular Mode values, both indices of maternal prey resources.4.Overall, large females weaned male pups that weighed 17 kg (15.5%) more than female pups. Maternal condition varied by as much as 59 kg among years, and was positively related to SAM, and negatively to maximum sea-ice extent. Smaller mothers weaned relatively larger male pups under favourable conditions, this effect was less apparent for larger mothers.5.We developed a simple model linking environmental variation to maternal masses post-partum, followed by maternal masses post-partum to weaning masses and then weaning masses to pup survival and demonstrated that environmental conditions affected predicted survival so that the pups of small mothers had an estimated 7% increase in first year survival in “good” vs “bad” years compared to 1% for female pups of large mothers.6.Co-occurrence of environmental quality and conservative reproductive tactics suggests that mothers retain substantial plasticity in maternal care, enhancing their lifetime reproductive success by adjusting reproductive expenditure relative to both prevailing environmental conditions and their own capabilities.This article is protected by copyright. All rights reserved.
      PubDate: 2016-11-18T11:45:19.211547-05:
      DOI: 10.1111/1365-2656.12611
       
  • Combining familiarity and landscape features helps break down the barriers
           between movements and home ranges in a non-territorial large herbivore
    • Authors: Pascal Marchand; Mathieu Garel, Gilles Bourgoin, Antoine Duparc, Dominique Dubray, Daniel Maillard, Anne Loison
      First page: 371
      Abstract: 1.Recent advances in animal ecology have enabled identification of certain mechanisms that lead to the emergence of territories and home ranges from movements considered as unbounded. Among them, memory and familiarity have been identified as key parameters in cognitive maps driving animal navigation, but have been only recently used in empirical analyses of animal movements.2.At the same time, the influence of landscape features on movements of numerous species and on space division in territorial animals has been highlighted. Despite their potential as exocentric information in cognitive maps and as boundaries for home ranges, a few studies have investigated their role in the design of home ranges of non-territorial species.3.Using Step selection Analyses, we assessed the relative contribution of habitat characteristics, familiarity preferences and linear landscape features in movement step selection of 60 GPS-collared Mediterranean mouflon monitored in southern France. Then, we evaluated the influence of these movement-impeding landscape features on the design of home ranges by testing for a non random distribution of these behavioural barriers within sections of space differentially used by mouflon.4.We reveal that familiarity and landscape features are key determinants of movements, relegating to a lower level certain habitat constraints (e.g. food/cover trade-off) that we had previously identified as important for this species. Mouflon generally avoid crossing both anthropogenic (i.e. roads, tracks and hiking trails) and natural landscape features (i.e. ridges, talwegs and forest edges) while moving in the opposite direction, preferentially toward familiar areas. These specific behaviours largely depend on the relative position of each movement step regarding distance to the landscape features or level of familiarity in the surroundings. We also revealed cascading consequences on the design of home ranges in which most landscape features were excluded from cores and relegated to the peripheral areas.5.These results provide crucial information on landscape connectivity in a context of marked habitat fragmentation. They also call for more research on the role of landscape features in the emergence of home ranges in non-territorial species using recent methodological developments bridging the gap between movements and space use patterns.This article is protected by copyright. All rights reserved.
      PubDate: 2016-12-15T22:50:36.841226-05:
      DOI: 10.1111/1365-2656.12616
       
  • Does movement behaviour predict population densities' A test with 25
           butterfly species
    • Authors: Cheryl B. Schultz; B. Guy Pe'er, Christine Damiani, Leone Brown, Elizabeth E. Crone
      First page: 384
      Abstract: Diffusion, which approximates a correlated random walk, has been used by ecologists to describe movement, and forms the basis for many theoretical models. However, it is often criticized as too simple a model to describe animal movement in real populations.We test a key prediction of diffusion models, namely, that animals should be more abundant in land cover classes through which they move more slowly. This relationship between density and diffusion has rarely been tested across multiple species within a given landscape.We estimated diffusion rates and corresponding densities of 25 Israeli butterfly species from flight path data and visual surveys. The data were collected across 19 sites in heterogeneous landscapes with four land cover classes: semi-natural habitat, olive groves, wheat fields, and field margins.As expected from theory, species tended to have higher densities in land cover classes through which they moved more slowly and lower densities in land cover classes through which they moved more quickly. Two components of movement (move length and turning angle) were not associated with density, nor was expected net squared displacement. Move time, however, was associated with density, and animals spent more time per move step in areas with higher density.The broad association we document between movement behaviour and density suggests that diffusion is a good first approximation of movement in butterflies. Moreover, our analyses demonstrate that dispersal is not a species-invariant trait, but rather one that depends on landscape context. Thus land cover classes with high diffusion rates are likely to have low densities and be effective conduits for movement.This article is protected by copyright. All rights reserved.
      PubDate: 2016-11-17T07:15:29.741457-05:
      DOI: 10.1111/1365-2656.12609
       
  • Experimental evidence for sexual selection against inbred males
    • Authors: Regina Vega-Trejo; Megan L. Head, J. Scott Keogh, Michael D. Jennions
      First page: 394
      Abstract: (1)The detrimental effects of matings between relatives are well known. However, few studies determine the extent to which inbreeding depression in males is due to natural or sexual selection. Importantly, measuring fitness or key fitness components, rather than phenotypic traits allows more accurate estimation of inbreeding depression.(2)We investigate how differences in inbreeding and juvenile diet (i.e. early stressful environment) influence a key component of male fitness, namely their reproductive success.(3)We experimentally created inbred and outbred male mosquitofish (Gambusia holbrooki) by mating full-sibs (f=0.25). We show that this led to a 23% reduction in genome-wide heterozygosity based on SNPs. Males were raised on different diets early in life to create high-stress and low-stress rearing environments. We then allowed adult males to compete freely for females to test if inbreeding, early diet, and their interaction affect a male's share of paternity.(4)Early diet had no effect on paternity, but outbred males sired almost twice as many offspring as inbred males (n = 628 offspring from 122 potential sires). Using artificial insemination methods we determined that this was unlikely to be due to early embryo mortality of eggs fertilised by inbred males: there was no evidence that male inbreeding status affects the realised fecundity of females (n=288).(5)Given there was no difference in male mortality in our competitive mating experiment, the lower reproductive success of inbred males can most parsimoniously be attributed to inbreeding negatively affecting sexually selected traits that affect male mating success and/or sperm competitiveness. We discuss which sexually selected traits might be involved.This article is protected by copyright. All rights reserved.
      PubDate: 2016-12-14T09:40:23.856286-05:
      DOI: 10.1111/1365-2656.12615
       
  • Isotopic niches support the resource breadth hypothesis
    • Authors: Jonathan A. Rader; Seth D. Newsome, Pablo Sabat, R. Terry Chesser, Michael E. Dillon, Carlos Martínez del Rio
      First page: 405
      Abstract: Because a broad spectrum of resource use allows species to persist in a wide range of habitat types, and thus permits them to occupy large geographical areas, and because broadly distributed species have access to more diverse resource bases, the resource breadth hypothesis posits that the diversity of resources used by organisms should be positively related with the extent of their geographic ranges.We investigated isotopic niche width in a small radiation of South American birds in the genus Cinclodes. We analyzed feathers of 12 species of Cinclodes to test the isotopic version of the resource breadth hypothesis and to examine the correlation between isotopic niche breadth and morphology.We found a positive correlation between the widths of hydrogen and oxygen isotopic niches (which estimate breadth of elevational range) and widths of the carbon and nitrogen isotopic niches (which estimates the diversity of resources consumed, and hence of habitats used). We also found a positive correlation between broad isotopic niches and wing morphology.Our study not only supports the resource breadth hypothesis, it highlights the usefulness of stable isotope analyses as tools in the exploration of ecological niches. It is an example of a macroecological application of stable isotopes. It also illustrates the importance of scientific collections in ecological studies.This article is protected by copyright. All rights reserved.
      PubDate: 2016-12-22T07:10:33.834211-05:
      DOI: 10.1111/1365-2656.12629
       
 
 
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