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  Subjects -> BIOLOGY (Total: 2968 journals)
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ZOOLOGY (134 journals)                     

Showing 1 - 0 of 0 Journals sorted alphabetically
Acta Herpetologica     Open Access   (Followers: 4)
Acta Theriologica     Full-text available via subscription   (Followers: 6)
Acta Zoologica     Hybrid Journal   (Followers: 4)
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: 2)
African Journal of Wildlife Research     Full-text available via subscription   (Followers: 2)
African Zoology     Hybrid Journal   (Followers: 6)
American Journal of Zoological Research     Open Access   (Followers: 1)
Animal Behaviour     Hybrid Journal   (Followers: 126)
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: 2)
Annual Review of Animal Biosciences     Full-text available via subscription   (Followers: 4)
Anthrozoos : A Multidisciplinary Journal of The Interactions of People & Animals     Hybrid Journal   (Followers: 7)
Applied Animal Behaviour Science     Hybrid Journal   (Followers: 18)
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  
Arthropod Management Tests     Hybrid Journal   (Followers: 2)
Asian Journal of Animal and Veterinary Advances     Open Access   (Followers: 7)
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: 24)
Brazilian Journal of Veterinary Research and Animal Science     Open Access   (Followers: 8)
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)
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: 59)
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: 3)
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: 10)
Journal of Morphology     Hybrid Journal   (Followers: 4)
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: 34)
Journal of Zoo and Aquarium Research     Open Access   (Followers: 4)
Journal of Zoological Systematics and Evolutionary Research     Hybrid Journal   (Followers: 3)
Journal of Zoology     Hybrid Journal   (Followers: 20)
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  
New Zealand Journal of Zoology     Hybrid Journal   (Followers: 3)
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: 15)
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: 1)
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: 1)
South American Journal of Herpetology     Full-text available via subscription   (Followers: 3)
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: 4)
Zoologia (Curitiba)     Open Access   (Followers: 1)
Zoologica Poloniae : The Journal of Polish Zoological Society     Open Access   (Followers: 1)
Zoologica Scripta     Hybrid Journal   (Followers: 2)
Zoological Journal of the Linnean Society     Hybrid Journal   (Followers: 9)
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: 2)
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]   [59 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]
  • 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
       
  • Corrigendum
    • PubDate: 2017-01-18T04:45:22.52792-05:0
      DOI: 10.1111/1365-2656.12631
       
  • 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
      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
       
  • 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
       
  • 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
      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
       
  • Analysing animal social network dynamics: the potential of stochastic
           actor-orientated models
    • Authors: David N. Fisher; Amiyaal Ilany, Matthew J. Silk, Tom Tregenza
      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
       
  • 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
      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
       
  • 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
      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
       
  • Experimentally reducing species abundance indirectly affects food web
           structure and robustness
    • Authors: Milton Barbosa; G. Wilson Fernandes, Owen T. Lewis, Rebecca J. Morris
      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
       
  • 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
      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
       
  • 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
      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
       
  • 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
      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
       
  • 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
       
  • Repeatability, heritability, and age-dependence in the aggressiveness
           reaction norms of a wild passerine bird
    • Authors: Yimen G. Araya-Ajoy; Niels J. Dingemanse
      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
       
  • 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
      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
       
  • Projected changes in prevailing winds for transatlantic migratory birds
           under global warming
    • Authors: Frank A. La Sorte; Daniel Fink
      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
       
  • Experimental evidence for sexual selection against inbred males
    • Authors: Regina Vega-Trejo; Megan L. Head, J. Scott Keogh, Michael D. Jennions
      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
       
  • Shrub encroachment is linked to extirpation of an apex predator
    • Authors: Christopher E. Gordon; David J. Eldridge, William J. Ripple, Mathew S. Crowther, Ben D. Moore, Mike Letnic
      Abstract: The abundance of shrubs has increased throughout Earth's arid lands. This ‘shrub encroachment’ has been linked to livestock grazing, fire-suppression and elevated atmospheric CO2 concentrations facilitating shrub recruitment. Apex predators initiate trophic cascades which can influence the abundance of many species across multiple trophic levels within ecosystems. Extirpation of apex predators is linked inextricably to pastoralism, but has not been considered as a factor contributing to shrub encroachment.Here, we ask if trophic cascades triggered by the extirpation of Australia's largest terrestrial predator, the dingo (Canis dingo), could be a driver of shrub encroachment in the Strzelecki Desert, Australia.We use aerial photographs spanning a 51-year period to compare shrub cover between areas where dingoes are historically rare and common. We then quantify contemporary patterns of shrub, shrub seedling and mammal abundances, and use structural equation modelling to compare competing trophic cascade hypotheses to explain how dingoes could influence shrub recruitment. Finally, we track the fate of seedlings of an encroaching shrub, hopbush (Dodonaea viscosa angustissima), during a period optimal for seedling recruitment, and quantify removal rates of hopbush seeds by rodents from enriched seed patches.Shrub cover was 26–48% greater in areas where dingoes were rare than common. Our structural equation modelling supported the hypothesis that dingo removal facilitates shrub encroachment by triggering a four level trophic cascade. According to this model, increased mesopredator abundance in the absence of dingoes results in suppressed abundance of consumers of shrub seeds and seedlings, rodents and rabbits respectively. In turn, suppressed abundances of rodents and rabbits in the absence of dingoes relaxed a recruitment bottleneck for shrubs. The results of our SEM were supported by results showing that rates of hopbush seedling survival and seed removal were 1·7 times greater and 2·1 times lower in areas where dingoes were rare than common.Our study provides evidence linking the suppression of an apex predator to the historic encroachment of shrubs. We contend that trophic cascades induced by apex predator extirpation may be an overlooked driver of shrub encroachment.Shrub cover has increased throughout Earth's rangelands. The authors propose a novel model accounting for this ‘shrub encroachment’: trophic cascades induced by apex predator extirpation facilitate shrub recruitment and success. GIS tools, field data and statistical techniques are used to test this model in arid Australia.
      PubDate: 2016-12-05T07:11:34.601425-05:
      DOI: 10.1111/1365-2656.12607
       
  • Precipitation alters interactions in a grassland ecological community
    • Authors: Nicolas Deguines; Justin S. Brashares, Laura R. Prugh
      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
       
  • Temporal shifts and temperature sensitivity of avian spring migratory
           phenology: A phylogenetic meta-analysis
    • Authors: T Usui; S H M Butchart, A B Phillimore
      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
       
  • 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
      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
       
  • 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
      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
       
  • 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
      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
       
  • Climatic conditions cause spatially dynamic polygyny thresholds in a large
           mammal
    • Authors: Jeffrey A. Manning; Philip D. McLoughlin
      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
       
  • 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
      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
      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
       
  • 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
       
  • Let's stay together? Intrinsic and extrinsic factors involved in pair bond
           dissolution in a recolonizing wolf population
    • Authors: Cyril Milleret; Petter Wabakken, Olof Liberg, Mikael Åkesson, Øystein Flagstad, Harry Peter Andreassen, Håkan Sand
      Abstract: For socially monogamous species, breeder bond dissolution has important consequences for population dynamics, but the extent to which extrinsic or intrinsic population factors causes pair dissolution remain poorly understood, especially among carnivores.Using an extensive life-history data set, a survival analysis and competing risks framework, we examined the fate of 153 different wolf (Canis lupus) pairs in the recolonizing Scandinavian wolf population, during 14 winters of snow tracking and DNA monitoring.Wolf pair dissolution was generally linked to a mortality event and was strongly affected by extrinsic (i.e. anthropogenic) causes. No divorce was observed, and among the pair dissolution where causes have been identified, death of one or both wolves was always involved. Median time from pair formation to pair dissolution was three consecutive winters (i.e. approximately 2 years). Pair dissolution was mostly human-related, primarily caused by legal control actions (36·7%), verified poaching (9·2%) and traffic-related causes (2·1%). Intrinsic factors, such as disease and age, accounted for only 7·7% of pair dissolutions. The remaining 44·3% of dissolution events were from unknown causes, but we argue that a large portion could be explained by an additional source of human-caused mortality, cryptic poaching.Extrinsic population factors, such as variables describing the geographical location of the pair, had a stronger effect on risk of pair dissolution compared to anthropogenic landscape characteristics. Population intrinsic factors, such as the inbreeding coefficient of the male pair member, had a negative effect on pair bond duration. The mechanism behind this result remains unknown, but might be explained by lower survival of inbred males or more complex inbreeding effects mediated by behaviour.Our study provides quantitative estimates of breeder bond duration in a social carnivore and highlights the effect of extrinsic (i.e. anthropogenic) and intrinsic factors (i.e. inbreeding) involved in wolf pair bond duration. Unlike the effects of intrinsic and extrinsic factors that are commonly reported on individual survival or population growth, here we provide quantitative estimates of their potential effect on the social unit of the population, the wolf pair.Few estimates of pair bond duration are available for social species, especially for carnivores. The authors found that wolf pair bond duration in Scandinavia was short (half of the dissolution events occurred after three consecutive winters), and dissolutions were mostly caused by humans. This shows the impact of extrinsic factors (i.e. humans) on the social unit of this large carnivore population.
      PubDate: 2016-09-28T03:32:06.434028-05:
      DOI: 10.1111/1365-2656.12587
       
  • Forbidden fruit: human settlement and abundant fruit create an ecological
           trap for an apex omnivore
    • Authors: Clayton T. Lamb; Garth Mowat, Bruce N. McLellan, Scott E. Nielsen, Stan Boutin
      Abstract: Habitat choice is an evolutionary product of animals experiencing increased fitness when preferentially occupying high-quality habitat. However, an ecological trap (ET) can occur when an animal is presented with novel conditions and the animal's assessment of habitat quality is poorly matched to its resulting fitness.We tested for an ET for grizzly (brown) bears using demographic and movement data collected in an area with rich food resources and concentrated human settlement.We derived measures of habitat attractiveness from occurrence models of bear food resources and estimated demographic parameters using DNA mark–recapture information collected over 8 years (2006–2013). We then paired this information with grizzly bear mortality records to investigate kill and movement rates.Our results demonstrate that a valley high in both berry resources and human density was more attractive than surrounding areas, and bears occupying this region faced 17% lower apparent survival. Despite lower fitness, we detected a net flow of bears into the ET, which contributed to a study-wide population decline.This work highlights the presence and pervasiveness of an ET for an apex omnivore that lacks the evolutionary cues, under human-induced rapid ecological change, to assess trade-offs between food resources and human-caused mortality, which results in maladaptive habitat selection.The authors tested for an ecological trap (ET) in south-east British Columbia where human settlement and rich grizzly bear habitat overlap. Bears occupying the ET faced survival consequences, which produced source–sink dynamics with far-reaching effects. To date, this is the most rigorous test of an ET for a large mammal.
      PubDate: 2016-09-28T00:00:02.394242-05:
      DOI: 10.1111/1365-2656.12589
       
  • Modeling effects of nonbreeders on population growth estimates
    • Authors: Aline M. Lee; Jane M. Reid, Steven R. Beissinger
      Abstract: 1.Adult individuals that do not breed in a given year occur in a wide range of natural populations. However, such nonbreeders are often ignored in theoretical and empirical population studies, limiting our knowledge of how nonbreeders affect realized and estimated population dynamics and potentially impeding projection of deterministic and stochastic population growth rates.2.We present and analyze a general modeling framework for systems where breeders and nonbreeders differ in key demographic rates, incorporating different forms of nonbreeding, different life histories, and frequency-dependent effects of nonbreeders on demographic rates of breeders.3.Comparisons of estimates of deterministic population growth rate, λ, and demographic variance, σ2d, from models with and without distinct nonbreeder classes show that models that do not explicitly incorporate nonbreeders give upwardly biased estimates of σ2d, particularly when the equilibrium ratio of nonbreeders to breeders, N*nb/N*b, is high. Estimates of λ from empirical observations of breeders only are substantially inflated when individuals frequently re-enter the breeding population after periods of nonbreeding.4.Sensitivity analyses of diverse parameterizations of our model framework, with and without negative frequency-dependent effects of nonbreeders on breeder demographic rates, show how changes in demographic rates of breeders versus nonbreeders differentially affect λ. In particular, λ is most sensitive to nonbreeder parameters in long-lived species, when N*nb/N*b > 0, and when individuals are unlikely to breed at several consecutive time steps.5.Our results demonstrate that failing to account for nonbreeders in population studies can obscure low population growth rates that should cause management concern. Quantifying the size and demography of the nonbreeding section of populations and modeling appropriate demographic structuring is therefore essential to evaluate nonbreeders’ influence on deterministic and stochastic population dynamics.This article is protected by copyright. All rights reserved.
      PubDate: 2016-09-14T04:50:57.949622-05:
      DOI: 10.1111/1365-2656.12592
       
  • Intra-specific competition, not predation, drives lizard tail loss on
           islands
    • Authors: Yuval Itescu; Rachel Schwarz, Shai Meiri, Panayiotis Pafilis
      Abstract: Tail autotomy is mainly considered an anti-predator mechanism. Theory suggests predation pressure relaxes on islands, subsequently reducing autotomy rates. Intra-specific aggression, which may also cause tail loss, probably intensifies on islands due to the higher abundance. We studied whether tail autotomy is mostly affected by predation pressure or by intra-specific competition. We further studied whether predator abundance or predator richness is more important in this context.To test our predictions we examined multiple populations of two gecko species: Kotschy's gecko (Mediodactylus kotschyi; mainland and 41 islands) and the Mediterranean house gecko (Hemidactylus turcicus; mainland and 17 islands), and estimated their abundances together with five indices of predation.In both species autotomy rates are higher on islands and decline with most predation indices, in contrast with common wisdom, and increase with gecko abundance. In M. kotschyi tail loss rates are higher on predator and viper-free islands, but increase with viper abundance. We suggest that autotomy is not simply, or maybe even mainly, an anti-predatory mechanism. Rather, such defense mechanisms are a response to complex direct and indirect biotic interactions and perhaps, in the case of tail autotomy in insular populations, chiefly to intra-specific aggression.This article is protected by copyright. All rights reserved.
      PubDate: 2016-09-14T02:10:31.070689-05:
      DOI: 10.1111/1365-2656.12591
       
  • Cascading effects of defaunation on the coexistence of two specialized
           insect seed predators
    • Authors: Guille Peguero; Helene C. Muller-Landau, Patrick A. Jansen, S. Joseph Wright
      Abstract: Identification of the mechanisms enabling stable coexistence of species with similar resource requirements is a central challenge in ecology. Such coexistence can be facilitated by species at higher trophic levels through complex multi-trophic interactions, a mechanism that could be compromised by ongoing defaunation.We investigated cascading effects of defaunation on Pachymerus cardo and Speciomerus giganteus, the specialized insect seed predators of the Neotropical palm Attalea butyracea, testing the hypothesis that vertebrate frugivores and granivores facilitate their coexistence.Lab experiments showed that the two seed parasitoid species differed strongly in their reproductive ecology. Pachymerus produced many small eggs that it deposited exclusively on the fruit exocarp (exterior). Speciomerus produced few large eggs that it deposited exclusively on the endocarp, which is normally exposed only after a vertebrate handles the fruit. When eggs of the two species were deposited on the same fruit, Pachymerus triumphed only when it had a long head start, and the loser always succumbed to intraguild predation.We collected field data on the fates of 6569 Attalea seeds across sites in central Panama with contrasting degrees of defaunation and wide variation in the abundance of vertebrate frugivores and granivores. Speciomerus dominated where vertebrate communities were intact, whereas Pachymerus dominated in defaunated sites. Variation in the relative abundance of Speciomerus across all 84 sampling sites was strongly positively related with the proportion of seeds attacked by rodents, an indicator of local vertebrate abundance.Synthesis: We show that two species of insect seed predators relying on the same host plant species are niche differentiated in their reproductive strategies such that one species has the advantage when fruits are handled promptly by vertebrates and the other when they aren't. Defaunation disrupts this mediating influence of vertebrates and strongly favors one species at the expense of the other, providing a case study of the cascading effects of defaunation and its potential to disrupt coexistence of non-target species, including the hyperdiverse phytophagous insects of tropical forests.This article is protected by copyright. All rights reserved.
      PubDate: 2016-09-09T11:01:40.388212-05:
      DOI: 10.1111/1365-2656.12590
       
  • Hunting promotes sexual conflict in brown bears
    • Authors: Jacinthe Gosselin; Martin Leclerc, Andreas Zedrosser, Sam M. J. G. Steyaert, Jon E. Swenson, Fanie Pelletier
      Abstract: The removal of individuals through hunting can destabilize social structure, potentially affecting population dynamics. Although previous studies have shown that hunting can indirectly reduce juvenile survival through increased sexually selected infanticide (SSI), very little is known about the spatiotemporal effects of male hunting on juvenile survival.Using detailed individual monitoring of a hunted population of brown bears (Ursus arctos) in Sweden (1991–2011), we assessed the spatiotemporal effect of male removal on cub survival.We modelled cub survival before, during and after the mating season. We used three proxies to evaluate spatial and temporal variation in male turnover; distance and timing of the closest male killed and number of males that died around a female's home range centre.Male removal decreased cub survival only during the mating season, as expected in seasonal breeders with SSI. Cub survival increased with distance to the closest male killed within the previous 1·5 years, and it was lower when the closest male killed was removed 1·5 instead of 0·5 year earlier. We did not detect an effect of the number of males killed.Our results support the hypothesis that social restructuring due to hunting can reduce recruitment and suggest that the distribution of the male deaths might be more important than the overall number of males that die. As the removal of individuals through hunting is typically not homogenously distributed across the landscape, spatial heterogeneity in hunting pressure may cause source–sink dynamics, with lower recruitment in areas of high human-induced mortality.The authors explored detailed spatiotemporal effects of male hunting on juvenile survival in brown bears, a species with sexually selected infanticide. The distribution of kills might be more important for juvenile survival than the number of males killed. Thus, reducing harvest intensity might not always increase population growth.
      PubDate: 2016-08-30T08:35:33.021489-05:
      DOI: 10.1111/1365-2656.12576
       
  • Genetic mixture of multiple source populations accelerates invasive range
           expansion
    • Authors: Natalie K. Wagner; Brad M. Ochocki, Kerri M. Crawford, Aldo Compagnoni, Tom E.X. Miller
      Abstract: A wealth of population genetic studies have documented that many successful biological invasions stem from multiple introductions from genetically distinct source populations. Yet, mechanistic understanding of whether and how genetic mixture promotes invasiveness has lagged behind documentation that such mixture commonly occurs. We conducted a laboratory experiment to test the influence of genetic mixture on the velocity of invasive range expansion.The mechanistic basis for effects of genetic mixture could include evolutionary responses (mixed invasions may harbour greater genetic diversity and thus elevated evolutionary potential) and/or fitness advantages of between-population mating (heterosis). If driven by evolution, positive effects of source population mixture should increase through time, as selection sculpts genetic variation. If driven by heterosis, effects of mixture should peak following first reproductive contact and then dissipate.Using a laboratory model system (beetles spreading through artificial landscapes), we quantified the velocity of range expansion for invasions initiated with one, two, four or six genetic sources over six generations. Our experiment was designed to test predictions corresponding to the evolutionary and heterosis mechanisms, asking whether any effects of genetic mixture occurred in early or later generations of range expansion. We also quantified demography and dispersal for each experimental treatment, since any effects of mixture should be manifest in one or both of these traits.Over six generations, invasions with any amount of genetic mixture (two, four and six sources) spread farther than single-source invasions. Our data suggest that heterosis provided a ‘catapult effect’, leaving a lasting signature on range expansion even though the benefits of outcrossing were transient. Individual-level trait data indicated that genetic mixture had positive effects on local demography (reduced extinction risk and enhanced population growth) during the initial stages of invasion but no consistent effects on dispersal ability.Our work is the first to demonstrate that genetic mixture can alter the course of spatial expansion, the stage of invasion typically associated with the greatest ecological and economic impacts. We suggest that similar effects of genetic mixture may be a common feature of biological invasions in nature, but that these effects can easily go undetected.Genetic mixture of multiple source populations can catapult the spread of biological invasions.
      PubDate: 2016-08-08T10:22:21.413438-05:
      DOI: 10.1111/1365-2656.12567
       
  • Like a rolling stone: the dynamic world of animal ecology publishing
    • Authors: Kenneth Wilson; Ben C. Sheldon, Jean-Michel Gaillard, Nathan J. Sanders, Simon P. G. Hoggart, Erika Newton
      First page: 1
      PubDate: 2016-12-12T05:12:45.387208-05:
      DOI: 10.1111/1365-2656.12606
       
  • Admixture is a driver rather than a passenger in experimental invasions
    • Authors: Ruth A. Hufbauer
      First page: 4
      Abstract: Genetic admixture propels invasions of Callosobruchus maculatus across experimental landscapes.In Focus: Wagner, N.K., Ochocki, B.M., Crawford, K.M., Compagnoni, A. & Miller, T.E.X. (2017) Genetic mixture of multiple source populations accelerates invasive range expansion. Journal of Animal Ecology, 86, 21–34.In this issue of Journal of Animal Ecology, Wagner et al. (2017) demonstrate that genetic diversity can alter the course of spread of biological invasions. They employ Callosobruchus seed beetles in a clever array of linked habitat patches to compare experimental invasions using individuals from single population sources or from mixes of two, four or six population sources. By taking a model-selection approach, they find that any amount of mixture propels growth rates and spread of introduced populations. This suggests that heterosis alone can alter the course of an invasive range expansion.Genetic admixture propels invasions of Callosobruchus maculatus across experimental landscapes.
      PubDate: 2016-12-12T05:12:48.074136-05:
      DOI: 10.1111/1365-2656.12600
       
  • Accounting for genetic differences among unknown parents in
           microevolutionary studies: How to include genetic groups in quantitative
           genetic animal models
    • Authors: Matthew E. Wolak; Jane M. Reid
      First page: 7
      Abstract: 1.Quantifying and predicting microevolutionary responses to environmental change requires unbiased estimation of quantitative genetic parameters in wild populations. ‘Animal models’, which utilise pedigree data to separate genetic and environmental effects on phenotypes, provide powerful means to estimate key parameters and have revolutionised quantitative genetic analyses of wild populations.2.However, pedigrees collected in wild populations commonly contain many individuals with unknown parents. When unknown parents are non-randomly associated with genetic values for focal traits, animal model parameter estimates can be severely biased. Yet, such bias has not previously been highlighted and statistical methods designed to minimise such biases have not been implemented in evolutionary ecology.3.We first illustrate how the occurrence of non-random unknown parents in population pedigrees can substantially bias animal model predictions of breeding values and estimates of additive genetic variance, and create spurious temporal trends in predicted breeding values in the absence of local selection. We then introduce ‘genetic group’ methods, which were developed in agricultural science, and explain how these methods can minimise bias in quantitative genetic parameter estimates stemming from genetic heterogeneity among individuals with unknown parents.4.We summarise the conceptual foundations of genetic group animal models and provide extensive, step-by-step tutorials that demonstrate how to fit such models in a variety of software programs. Furthermore, we provide new functions in R that extend current software capabilities and provide a standardized approach across software programs to implement genetic group methods.5.Beyond simply alleviating bias, genetic group animal models can directly estimate new parameters pertaining to key biological processes. We discuss one such example, where genetic group methods potentially allow the microevolutionary consequences of local selection to be distinguished from effects of immigration and resulting gene flow.6.We highlight some remaining limitations of genetic group models and discuss opportunities for further development and application in evolutionary ecology. We suggest that genetic group methods should no longer be overlooked by evolutionary ecologists, but should become standard components of the toolkit for animal model analyses of wild population datasets.This article is protected by copyright. All rights reserved.
      PubDate: 2016-10-12T05:55:43.070355-05:
      DOI: 10.1111/1365-2656.12597
       
  • African departure rather than migration speed determines variation in
           spring arrival in pied flycatchers
    • Authors: J. Ouwehand; C. Both
      First page: 88
      Abstract: 1.Properly timed spring migration enhances reproduction and survival. Climate change requires organisms to respond to changes such as advanced spring phenology. Pied flycatchers Ficedula hypoleuca have become a model species to study such phenological adaptations of long-distance migratory songbirds to climate change, but data on individuals’ time schedules outside the breeding season are still lacking.2.Using light-level geolocators we studied variation in migration schedules across the year in a pied flycatcher population in the Netherlands, which sheds light on the ability for individual adjustments in spring arrival timing to track environmental changes at their breeding grounds.3.We show that variation in arrival dates to breeding sites in 2014 was caused by variation in departure date from Sub-Saharan Africa, and not by environmental conditions encountered en route. Spring migration duration was short for all individuals, on average two weeks. Males migrated ahead of females in spring, while migration schedules in autumn were flexibly adjusted according to breeding duties. Individuals were therefore not consistently early or late throughout the year.4.In fast migrants like our Dutch pied flycatchers, advancement of arrival to climate change likely requires changes in spring departure dates. Adaptation for earlier arrival may be slowed down by harsh circumstances in winter, or years with high costs associated with early migration.This article is protected by copyright. All rights reserved.
      PubDate: 2016-10-10T21:05:30.514229-05:
      DOI: 10.1111/1365-2656.12599
       
  • Earlier nesting by generalist predatory bird is associated with human
           responses to climate change
    • Authors: Shawn H. Smith; Karen Steenhof, Christopher J.W. McClure, Julie A. Heath
      First page: 98
      Abstract: Warming temperatures cause temporal changes in growing seasons and prey abundance that drive earlier breeding by birds, especially dietary specialists within homogeneous habitat. Less is known about how generalists respond to climate-associated shifts in growing seasons or prey phenology, which may occur at different rates across land cover types.We studied whether breeding phenology of a generalist predator, the American kestrel (Falco sparverius), was associated with shifts in growing seasons and, presumably, prey abundance, in a mosaic of non-irrigated shrub/grasslands and irrigated crops/pastures. We examined the relationship between remotely-sensed normalized difference vegetation index (NDVI) and abundance of small mammals that, with insects, constitute approximately 93% of kestrel diet biomass. We used NDVI to estimate the start of the growing season (SoGS) in irrigated and non-irrigated lands from 1992 to 2015 and tested whether either estimate of annual SoGS predicted the timing of kestrel nesting. Finally, we examined relationships among irrigated SoGS, weather and crop planting.NDVI was a useful proxy for kestrel prey because it predicted small mammal abundance and past studies showed that NDVI predicts insect abundance. NDVI-estimated SoGS advanced significantly in irrigated lands (β = −1·09 ± 0·30 SE) but not in non-irrigated lands (β = −0·57 ± 0·53). Average date of kestrel nesting advanced 15 days in the past 24 years and was positively associated with the SoGS in irrigated lands, but not the SoGS in non-irrigated lands. Advanced SoGS in irrigated lands was related to earlier planting of crops after relatively warm winters, which were more common in recent years.Despite different patterns of SoGS change between land cover types, kestrel nesting phenology shifted with earlier prey availability in irrigated lands. Kestrels may preferentially track prey in irrigated lands over non-irrigated lands because of higher quality prey on irrigated lands, or earlier prey abundance may release former constraints on other selective pressures to breed early, such as seasonal declines in fecundity or competition for high-quality mates.This is one of the first examples of an association between human adaptation to climate change and shifts in breeding phenology of wildlife.American kestrels, inhabiting a mosaic of habitats, nested earlier in response to earlier prey availability in agriculture, but not wildlands. Prey in agriculture were earlier because farmers planted crops earlier following warmer winters. This suggests an association between human adaptation to climate change and shifts in breeding phenology of wildlife.
      PubDate: 2016-11-21T19:00:02.552334-05:
      DOI: 10.1111/1365-2656.12604
       
  • Sensitivity of UK butterflies to local climatic extremes: which life
           stages are most at risk'
    • Authors: Osgur McDermott Long; Rachel Warren, Jeff Price, Tom M. Brereton, Marc S. Botham, Aldina M. A. Franco
      First page: 108
      Abstract: There is growing recognition as to the importance of extreme climatic events (ECEs) in determining changes in species populations. In fact, it is often the extent of climate variability that determines a population's ability to persist at a given site.This study examined the impact of ECEs on the resident UK butterfly species (n = 41) over a 37-year period. The study investigated the sensitivity of butterflies to four extremes (drought, extreme precipitation, extreme heat and extreme cold), identified at the site level, across each species' life stages. Variations in the vulnerability of butterflies at the site level were also compared based on three life-history traits (voltinism, habitat requirement and range).This is the first study to examine the effects of ECEs at the site level across all life stages of a butterfly, identifying sensitive life stages and unravelling the role life-history traits play in species sensitivity to ECEs.Butterfly population changes were found to be primarily driven by temperature extremes. Extreme heat was detrimental during overwintering periods and beneficial during adult periods and extreme cold had opposite impacts on both of these life stages. Previously undocumented detrimental effects were identified for extreme precipitation during the pupal life stage for univoltine species. Generalists were found to have significantly more negative associations with ECEs than specialists.With future projections of warmer, wetter winters and more severe weather events, UK butterflies could come under severe pressure given the findings of this study.This paper tackles a previously understudied field, addressing the impacts of extreme weather on biodiversity specifically butterflies in this study. It has used novel and dynamic approaches to identify extreme weather events which vary according to the life stage for each species and has identified some very interesting results.
      PubDate: 2016-10-31T03:35:24.884581-05:
      DOI: 10.1111/1365-2656.12594
       
  • Sexual selection can both increase and decrease extinction probability:
           reconciling demographic and evolutionary factors
    • Authors: Carlos Martínez-Ruiz; Robert J. Knell
      First page: 117
      Abstract: Previous theoretical models of the effect of sexual selection on average individual fitness in a population have mostly predicted that sexually selected populations should adapt faster and clear deleterious mutations more quickly than populations where sexual selection is not operating.While some laboratory studies have supported these predictions, others have not and studies of field systems have tended to find negative effects of sexual selection, or no effect. The negative effects of sexual selection found in field and other studies are usually ascribed to the costs associated with strong sexual selection acting on the population.Here, using an individual-based model that allows feedback between demographic and evolutionary processes, we find that sexual selection can lead to both increases and decreases in population-level fitness measures such as extinction probability and adaptation rate. Whether fitness increases or decreases depends on a variety of environmental and demographic factors including the nature of environmental change, the carrying capacity of the environment, the average fecundity of the population in question and the strength of condition dependence.In many cases, our model predicts that sexual selection leads to higher extinction probability in small populations because of an increased risk of demographic stochasticity, but lower extinction probability in larger populations because of faster adaptation rates. This is consistent with field studies that have mostly focussed on very small populations such as recently introduced birds, and tend to find negative effects, and also with laboratory studies that tend to use larger populations and have tended to find positive effects.These findings go at least some way towards an understanding of the apparent contradictions between theoretical predictions, laboratory studies and field data.Choosy females and males with bright or loud displays can change how a population responds to environmental stress. Large populations are made more resilient to stress, but small populations are more vulnerable.
      PubDate: 2016-11-14T04:35:36.152994-05:
      DOI: 10.1111/1365-2656.12601
       
  • Intra-specific priority effects modify compensatory responses to changes
           in hatching phenology in an amphibian
    • Authors: Andrea P. Murillo-Rincón; Nora A. Kolter, Anssi Laurila, Germán Orizaola
      First page: 128
      Abstract: 1.In seasonal environments, modifications in the phenology of life-history events can alter the strength of time-constraints experienced by organisms. Offspring can compensate for a change in timing of hatching by modifying their growth and development trajectories. However, intra- and inter -specific interactions may affect these compensatory responses, in particular if differences in phenology between cohorts lead to significant priority effects (i.e. the competitive advantage that early hatching individuals have over late hatching ones).2.Here, we conducted a factorial experiment to determine if intra-specific priority effects can alter compensatory phenotypic responses to hatching delay in a synchronic breeder by rearing moor frog (Rana arvalis) tadpoles in different combinations of phenological delay and food abundance.3.Tadpoles compensated for the hatching delay by speeding up their development, but only when reared in groups of individuals with identical hatching phenology. In mixed-phenology groups, strong competitive effects by non-delayed tadpoles prevented the compensatory responses, and delayed larvae metamorphosed later than in single phenology treatments. Non-delayed individuals gained advantage from developing with delayed larvae by increasing their developmental and growth rates as compared to single phenology groups.4.Food shortage prolonged larval period and reduced mass at metamorphosis in all treatments, but it did not prevent compensatory developmental responses in larvae reared in single phenology groups.5.This study demonstrates that strong intra-specific priority effects can constrain the compensatory growth and developmental responses to phenological change, and that priority effects can be an important factor explaining the maintenance of synchronic life-histories (i.e. explosive breeding) in seasonal environments.This article is protected by copyright. All rights reserved.
      PubDate: 2016-11-28T07:00:28.154774-05:
      DOI: 10.1111/1365-2656.12605
       
  • Decoupled diversity dynamics in green and brown webs during primary
           succession in a salt marsh
    • Authors: Maarten Schrama; Fons der Plas, Matty P. Berg, Han Olff
      First page: 158
      Abstract: 1.Terrestrial ecosystems are characterised by a strong functional connection between the green (plant-herbivore-based) and brown (detritus-detritivore-based) parts of the food web, which both develop over successional time. However, the interlinked changes in green and brown food web diversity patterns in relation to key ecosystem processes are rarely studied.2.Here, we demonstrate changes in species richness, diversity and evenness over a wide range of invertebrate green and brown trophic groups during 100 years of primary succession in a salt marsh ecosystem, using a well-calibrated chronosequence.3.We contrast two hypotheses on the relationship between green and brown food web diversity across succession: i) ‘coupled diversity hypothesis’, which predicts that all trophic groups covary similarly with the main drivers of successional ecosystem assembly versus ii) the ‘decoupled diversity hypothesis’, where green and brown trophic groups diversity respond to different drivers during succession.4.We found that, while species richness for plants and invertebrate herbivores (green web groups) both peaked at intermediate productivity and successional age, the diversity of macro-detritivores, microarthropod microbivores and secondary consumers (brown web groups) continuously increased towards the latest successional stages. These results suggest that green web trophic groups are mainly driven by vegetation parameters, such as the amount of bare soil, vegetation biomass production, and vegetation height, while brown web trophic groups are mostly driven by the production and standing stock of dead organic material and soil development.5.Our results show that plant diversity cannot simply be used as a proxy for the diversity of all other species groups that drive ecosystem functioning, as brown and green diversity components in our ecosystem responded differently to successional gradients.This article is protected by copyright. All rights reserved.
      PubDate: 2016-10-14T09:26:59.595831-05:
      DOI: 10.1111/1365-2656.12602
       
  • Corrigendum
    • First page: 170
      PubDate: 2016-10-17T05:07:09.786449-05:
      DOI: 10.1111/1365-2656.12595
       
  • Corrigendum
    • First page: 171
      PubDate: 2016-10-24T04:21:15.420102-05:
      DOI: 10.1111/1365-2656.12596
       
 
 
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