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  Subjects -> BIOLOGY (Total: 3026 journals)
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    - ZOOLOGY (135 journals)

ZOOLOGY (135 journals)                     

Showing 1 - 135 of 135 Journals sorted alphabetically
Acta Herpetologica     Open Access   (Followers: 8)
Acta Theriologica     Full-text available via subscription   (Followers: 6)
Acta Zoologica     Hybrid Journal   (Followers: 7)
Acta Zoologica Cracoviensia     Free   (Followers: 2)
Acta zoológica mexicana     Open Access  
Advances in Zoology and Botany     Open Access  
African Invertebrates     Open Access   (Followers: 1)
African Journal of Herpetology     Full-text available via subscription   (Followers: 7)
African Journal of Wildlife Research     Full-text available via subscription   (Followers: 4)
African Zoology     Hybrid Journal   (Followers: 6)
American Journal of Zoological Research     Open Access   (Followers: 1)
Animal Behaviour     Hybrid Journal   (Followers: 176)
Animal Biology     Hybrid Journal   (Followers: 9)
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: 8)
Annales Zoologici     Full-text available via subscription   (Followers: 1)
Annales Zoologici Fennici     Open Access   (Followers: 1)
Annals of Animal Science     Open Access   (Followers: 1)
Annals of the Ditsong National Museum of Natural History     Full-text available via subscription   (Followers: 3)
Annual Review of Animal Biosciences     Full-text available via subscription   (Followers: 5)
Anthrozoos : A Multidisciplinary Journal of The Interactions of People & Animals     Hybrid Journal   (Followers: 9)
Applied Animal Behaviour Science     Hybrid Journal   (Followers: 18)
Applied Entomology and Zoology     Partially Free   (Followers: 3)
Aquatic Mammals     Full-text available via subscription   (Followers: 8)
Aquatic Sciences     Hybrid Journal   (Followers: 13)
Arquivos de Ciências Veterinárias e Zoologia da UNIPAR     Open Access  
Arquivos de Zoologia     Open Access  
Arthropod Management Tests     Hybrid Journal   (Followers: 2)
Asian Journal of Animal and Veterinary Advances     Open Access   (Followers: 8)
Australian Journal of Zoology     Hybrid Journal   (Followers: 1)
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: 26)
BMC Zoology     Open Access  
Brazilian Journal of Veterinary Research and Animal Science     Open Access   (Followers: 7)
British Birds     Full-text available via subscription   (Followers: 27)
Bulletin of the Museum of Comparative Zoology     Full-text available via subscription   (Followers: 2)
Canadian Journal of Animal Science     Hybrid Journal   (Followers: 5)
Canadian Journal of Zoology     Hybrid Journal   (Followers: 16)
Canadian Zooarchaeology / Zooarchéologie canadienne     Open Access   (Followers: 2)
Contributions to Zoology     Open Access   (Followers: 3)
Current Zoology     Full-text available via subscription   (Followers: 1)
Der Zoologische Garten     Full-text available via subscription   (Followers: 2)
Ecology of Freshwater Fish     Hybrid Journal   (Followers: 17)
European Journal of Taxonomy     Open Access   (Followers: 4)
European Zoological Journal     Open Access  
Euscorpius     Open Access   (Followers: 1)
EvoDevo     Open Access   (Followers: 3)
Fish and Fisheries     Hybrid Journal   (Followers: 32)
Frontiers in Zoology     Open Access   (Followers: 6)
Graellsia     Open Access   (Followers: 1)
Herpetology Notes     Open Access   (Followers: 6)
Hystrix, the Italian Journal of Mammalogy     Open Access   (Followers: 1)
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: 5)
Invertebrate Reproduction & Development     Hybrid Journal   (Followers: 4)
Italian Journal of Animal Science     Open Access   (Followers: 3)
Italian Journal of Zoology     Hybrid Journal   (Followers: 2)
Journal of Agrobiology     Open Access   (Followers: 3)
Journal of Animal Ecology     Hybrid Journal   (Followers: 68)
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: 5)
Journal of Basic & Applied Zoology : Physiology     Open Access   (Followers: 2)
Journal of Experimental Zoology Part A: Ecological Genetics and Physiology     Hybrid Journal   (Followers: 4)
Journal of Experimental Zoology Part B : Molecular and Developmental Evolution     Hybrid Journal   (Followers: 2)
Journal of Freshwater Ecology     Hybrid Journal   (Followers: 14)
Journal of Herpetology     Full-text available via subscription   (Followers: 16)
Journal of Morphology     Hybrid Journal   (Followers: 5)
Journal of Threatened Taxa     Open Access  
Journal of Venomous Animals and Toxins     Open Access   (Followers: 4)
Journal of Venomous Animals and Toxins including Tropical Diseases     Open Access  
Journal of Wildlife Management     Hybrid Journal   (Followers: 38)
Journal of Zoological Systematics and Evolutionary Research     Hybrid Journal   (Followers: 4)
Journal of Zoology     Hybrid Journal   (Followers: 26)
Laboratory Animals     Hybrid Journal   (Followers: 14)
Mammalia     Hybrid Journal   (Followers: 5)
Mastozoología Neotropical     Open Access  
Monographs of the Transvaal Museum     Full-text available via subscription  
Natural History Sciences     Hybrid Journal   (Followers: 3)
New Zealand Journal of Zoology     Hybrid Journal   (Followers: 10)
Papéis Avulsos de Zoologia     Open Access  
Parasite     Open Access   (Followers: 4)
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: 20)
Research in Zoology     Open Access   (Followers: 2)
Revista Brasileira de Reprodução Animal     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: 4)
Scientific Journal of Animal Science     Open Access   (Followers: 6)
Scientific Journal of Zoology     Open Access   (Followers: 5)
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: 6)
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: 3)
University Journal of Zoology, Rajshahi University     Open Access  
Veterinária e Zootecnia     Open Access  
Waterbirds     Full-text available via subscription   (Followers: 11)
Wildlife Society Bulletin     Hybrid Journal   (Followers: 8)
World Rabbit Science     Open Access  
Zoo Biology     Hybrid Journal   (Followers: 10)
ZooKeys     Open Access   (Followers: 6)
Zoologia     Open Access  
Zoologia (Curitiba)     Open Access   (Followers: 1)
Zoologica Poloniae : The Journal of Polish Zoological Society     Open Access   (Followers: 1)
Zoologica Scripta     Hybrid Journal   (Followers: 4)
Zoological Journal of the Linnean Society     Hybrid Journal   (Followers: 15)
Zoological Letters     Open Access   (Followers: 1)
Zoological Science     Full-text available via subscription   (Followers: 3)
Zoological Studies     Open Access   (Followers: 2)
Zoologische Mededelingen     Open Access   (Followers: 1)
Zoologischer Anzeiger - A Journal of Comparative Zoology     Hybrid Journal   (Followers: 1)
Zoologist (The)     Full-text available via subscription   (Followers: 1)
Zoology     Hybrid Journal   (Followers: 6)
Zoology and Ecology     Hybrid Journal   (Followers: 5)
Zoomorphology     Hybrid Journal   (Followers: 3)
Zoosystematics and Evolution - Mitteilungen Aus Dem Museum Fur Naturkunde Zu Berlin     Open Access   (Followers: 1)

           

Journal Cover Journal of Animal Ecology
  [SJR: 3.359]   [H-I: 119]   [68 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  [1589 journals]
  • More invaders do not result in heavier impacts: the effects of nonnative
           bullfrogs on native anurans are mitigated by high densities of nonnative
           crayfish
    • Authors: Xuan Liu; Supen Wang, Zunwei Ke, Chaoyuan Cheng, Yihua Wang, Fang Zhang, Feng Xu, Xianping Li, Xu Gao, Changnan Jin, Wei Zhu, Shaofei Yan, Yiming Li
      Abstract: 1.With accelerating species introductions in an era of globalization, co‐occurring alien species have become increasingly common. Understanding the combined ecological impacts of multiple invaders is not only crucial for wildlife managers attempting to ameliorate biodiversity loss but also provides key insights into invasion success and species coexistence mechanisms in natural ecosystems. Compared with much attentions given to single invader impacts, little is known about the impacts of multiple co‐occurring invaders.2.The American bullfrog (Lithobates catesbeianus = Rana catesbeiana) and the red swamp crayfish (Procambarus clarkii) are two aquatic invasive species in many different areas of the globe. They co‐exist with native anurans in a variety of permanent lentic waters, which provide an ideal model system to explore the combined effects of multiple invaders from different trophic levels on native species.3.Based on a global diet analysis covering 34 native and invasive bullfrog populations, and data from 10‐year field surveys across 157 water bodies in the Zhoushan Archipelago, China, we observed a reduced impact of bullfrogs on native anurans at high crayfish densities when the two invaders co‐occurred.4.The global diet analysis showed that crayfish occurrence reduced the number of native anuran prey consumed by bullfrogs in both native and invasive populations. After accounting for pseudoreplication of different observations among water bodies, islands, and survey time, model averaging analyses based on generalized linear mixed models (GLMMs) showed a negative relationship between bullfrog density and native anuran densities for field observations of invasive bullfrogs alone and co‐invaded observations with low crayfish density. However, this negative relationship disappeared when the two invaders co‐occurred with high crayfish density. Structural equation modeling (SEM) analyses further validated that the impacts of bullfrogs on native frogs were mitigated by the negative interactions between crayfish and bullfrogs.5.Our results provide novel evidence of a density‐dependent antagonistic effect of two sympatric invaders from different trophic levels on native species. This study highlights the importance of considering complex interactions among co‐invaders and native species when prioritizing conservation and management actions and will facilitate the development of a more precise framework to predict invasion impacts.This article is protected by copyright. All rights reserved.
      PubDate: 2017-12-28T00:10:34.386105-05:
      DOI: 10.1111/1365-2656.12793
       
  • Dynamic occupancy modeling reveals a hierarchy of competition among
           fishers, gray foxes, and ringtails
    • Authors: David S. Green; Sean M. Matthews, Robert C. Swiers, Richard L. Callas, J. Scott Yaeger, Stuart Farber, Michael K. Schwartz, Roger A. Powell
      Abstract: 1.Determining how species coexist is critical for understanding functional diversity, niche partitioning and interspecific interactions. Identifying the direct and indirect interactions among sympatric carnivores that enable their coexistence are particularly important to elucidate because they are integral for maintaining ecosystem function.2.We studied the effects of removing 9 fishers (Pekania pennanti) on their population dynamics and used this perturbation to elucidate the interspecific interactions among fishers, gray foxes (Urocyon cinereoargenteus), and ringtails (Bassariscus astutus). Gray foxes (family: Canidae) are likely to compete with fishers due to their similar body sizes and dietary overlap, and ringtails (family: Procyonidae), like fishers, are semi‐arboreal species of conservation concern. We used spatial capture‐recapture to investigate fisher population numbers and dynamic occupancy models that incorporated interspecific interactions to investigate the effects members of these species had on the colonization and persistence of each other's site occupancy.3.The fisher population showed no change in density for up to three years following the removals of fishers for translocations. In contrast, fisher site occupancy decreased in the years immediately following the translocations. During this same time period, site occupancy by gray foxes increased and remained elevated through the end of the study.4.We found a complicated hierarchy among fishers, foxes, and ringtails. Fishers affected gray fox site persistence negatively but had a positive effect on their colonization. Foxes had a positive effect on ringtail site colonization. Thus, fishers were the dominant small carnivore where present and negatively affected foxes directly and ringtails indirectly.5.Coexistence among the small carnivores we studied appears to reflect dynamic spatial partitioning. Conservation and management efforts should investigate how intraguild interactions may influence the recolonization of carnivores to previously occupied landscapes.This article is protected by copyright. All rights reserved.
      PubDate: 2017-12-28T00:00:41.645473-05:
      DOI: 10.1111/1365-2656.12791
       
  • Rethinking ‘normal’: The role of stochasticity in the phenology of a
           synchronously breeding seabird
    • Authors: Casey Youngflesh; Stephanie Jenouvrier, Jefferson T. Hinke, Lauren DuBois, Judy St. Leger, Wayne Z. Trivelpiece, Susan G. Trivelpiece, Heather J. Lynch
      Abstract: 1.Phenological changes have been observed in a variety of systems over the past century. There is concern that, as a consequence, ecological interactions are becoming increasingly mismatched in time, with negative consequences for ecological function.2.Significant spatial heterogeneity (inter‐site) and temporal variability (inter‐annual) can make it difficult to separate intrinsic, extrinsic, and stochastic drivers of phenological variability. The goal of this study was to understand the timing and variability of breeding phenology of Adélie penguins under fixed environmental conditions, and to use those data to identify a ‘null model’ appropriate for disentangling the sources of variation in wild populations.3.Data on clutch initiation were collected from both wild and captive populations of Adélie penguins. Clutch initiation in the captive population was modeled as a function of year, individual, and age to better understand phenological patterns observed in the wild population.4.Captive populations displayed as much inter‐annual variability in breeding phenology as wild populations, suggesting that variability in breeding phenology is the norm and thus may be an unreliable indicator of environmental forcing. The distribution of clutch initiation dates was found to be moderately asymmetric (right skewed) both in the wild and in captivity, consistent with the pattern expected under social facilitation.5.The role of stochasticity in phenological processes has heretofore been largely ignored. However, these results suggest that inter‐annual variability in breeding phenology can arise independent of any environmental or demographic drivers and that synchronous breeding can enhance inherent stochasticity. This complicates efforts to relate phenological variation to environmental variability in the wild. Accordingly, we must be careful to consider random forcing in phenological processes, lest we fit models to data dominated by random noise. This is particularly true for colonial species where breeding synchrony may outweigh each individual's effort to time breeding with optimal environmental conditions. Our study highlights the importance of identifying appropriate null models for studying phenology.This article is protected by copyright. All rights reserved.
      PubDate: 2017-12-26T00:05:30.543788-05:
      DOI: 10.1111/1365-2656.12790
       
  • Disease implications of animal social network structure: a synthesis
           across social systems
    • Authors: Pratha Sah; Janet Mann, Shweta Bansal
      Abstract: 1.The disease costs of sociality have largely been understood through the link between group size and transmission. However, infectious disease spread is driven primarily by the social organization of interactions in a group and not its size.2.We used statistical models to review the social network organization of 47 species, including mammals, birds, reptiles, fish and insects by categorizing each species into one of three social systems, relatively solitary, gregarious and socially hierarchical. Additionally, using computational experiments of infection spread, we determined the disease costs of each social system.3.We find that relatively solitary species have large variation in number of social partners, that socially hierarchical species are the least clustered in their interactions, and that social networks of gregarious species tend to be the most fragmented. However, these structural differences are primarily driven by weak connections, which suggests that different social systems have evolved unique strategies to organize weak ties.4.Our synthetic disease experiments reveal that social network organization can mitigate the disease costs of group living for socially hierarchical species when the pathogen is highly transmissible. In contrast, highly transmissible pathogens cause frequent and prolonged epidemic outbreaks in gregarious species.5.We evaluate the implications of network organization across social systems despite methodological challenges, and our findings offer new perspective on the debate about the disease costs of group living. Additionally, our study demonstrates the potential of meta‐analytic methods in social network analysis to test ecological and evolutionary hypotheses on cooperation, group living, communication, and resilience to extrinsic pressures.This article is protected by copyright. All rights reserved.
      PubDate: 2017-12-15T21:10:29.498809-05:
      DOI: 10.1111/1365-2656.12786
       
  • A camera‐based method for estimating absolute density in animals
           displaying home range behaviour
    • Authors: Andrea Campos-Candela; Miquel Palmer, Salvador Balle, Josep Alós
      Abstract: 1.The measurement of animal density may take advantage of recent technological achievements in wildlife video recording. Fostering the theoretical links between the patterns depicted by cameras and absolute density is required to exploit this potential.2.We explore the applicability of the Hutchinson‐Waser's postulate (i.e., when animal density is stationary at a given temporal and spatial scale, the absolute density is given by the average number of animals counted per frame), which is a counter‐intuitive statement for most ecologists and managers who are concerned with counting the same individual more than once. We aimed to reconcile such skepticism for animals displaying home range behaviour.3.The specific objectives of this paper are to generalize the Hutchinson‐Waser's postulate for animals displaying home range behaviour and to propose a Bayesian implementation to estimate density from counts per frame using video cameras.4.Accuracy and precision of the method was evaluated by means of computer simulation experiments. Specifically, six animal archetypes displaying well‐contrasted movement features were considered. The simulation results demonstrate that density could be accurately estimated after an affordable sampling effort (i.e., number of cameras and deployment time) for a great number of animals across taxa.5.The proposed method may complement other conventional methods for estimating animal density. The major advantages are that identifying an animal at the individual level and precise knowledge on how animals move are not needed, and that density can be estimated in a single survey. The method can accommodate conventional camera trapping data. The major limitations are related to some implicit assumptions of the underlying model: the home range centres should be homogeneously distributed, the detection probability within the area surveyed by the camera should be known, and animals should move independently to one another. Further improvements for circumventing these limitations are discussed.This article is protected by copyright. All rights reserved.
      PubDate: 2017-12-15T03:37:49.199487-05:
      DOI: 10.1111/1365-2656.12787
       
  • Social behaviour and gut microbiota in red-bellied lemurs (Eulemur
           rubriventer): In search of the role of immunity in the evolution of
           sociality
    • Authors: Aura Raulo; Lasse Ruokolainen, Avery Lane, Katherine Amato, Rob Knight, Steven Leigh, Rebecca Stumpf, Bryan White, Karen E. Nelson, Andrea L. Baden, Stacey R. Tecot
      Abstract: Vertebrate gut microbiota form a key component of immunity and a dynamic link between an individual and the ecosystem. Microbiota might play a role in social systems as well, because microbes are transmitted during social contact and can affect host behaviour.Combining methods from behavioural and molecular research, we describe the relationship between social dynamics and gut microbiota of a group-living cooperative species of primate, the red-bellied lemur (Eulemur rubriventer). Specifically, we ask whether patterns of social contact (group membership, group size, position in social network, individual sociality) are associated with patterns of gut microbial composition (diversity and similarity) between individuals and across time.Red-bellied lemurs were found to have gut microbiota with slight temporal fluctuations and strong social group-specific composition. Contrary to expectations, individual sociality was negatively associated with gut microbial diversity. However, position within the social network predicted gut microbial composition.These results emphasize the role of the social environment in determining the microbiota of adult animals. Since social transmission of gut microbiota has the potential to enhance immunity, microbiota might have played an escalating role in the evolution of sociality.The authors show that composition of gut microbial communities reflect the social environment of Red-bellied lemurs: Individuals spending more time together in close physical contact share similar gut microbiota and most sociable individuals have distinct gut microbial communities. This reveals a new way by which social contact can modify individuals: Touch leads to sharing bacteria that have the potential to synchronize physiological processes.
      PubDate: 2017-12-05T00:00:02.566637-05:
      DOI: 10.1111/1365-2656.12781
       
  • A computer vision for animal ecology
    • Authors: Ben G. Weinstein
      Abstract: 1.A central goal of animal ecology is to observe species in the natural world. The cost and challenge of data collection often limit the breadth and scope of ecological study. Ecologists often use image capture to bolster data collection in time and space. However, the ability to process these images remains a bottleneck.2.Computer vision can greatly increase the efficiency, repeatability, and accuracy of image review. Computer vision uses image features, such as color, shape, and texture to infer image content.3.I provide a brief primer on ecological computer vision to outline its goals, tools and applications to animal ecology.4.I reviewed 187 existing applications of computer vision and divided articles into ecological description, counting, and identity tasks.5.I discuss recommendations for enhancing the collaboration between ecologists and computer scientists and highlight areas for future growth of automated image analysis.This article is protected by copyright. All rights reserved.
      PubDate: 2017-11-29T05:42:05.72346-05:0
      DOI: 10.1111/1365-2656.12780
       
  • A practical guide for inferring reliable dominance hierarchies and
           estimating their uncertainty
    • Authors: Alfredo Sánchez-Tójar; Julia Schroeder, Damien Roger Farine
      Abstract: 1.Many animal social structures are organized hierarchically, with dominant individuals monopolizing resources. Dominance hierarchies have received great attention from behavioural and evolutionary ecologists.2.There are many methods for inferring hierarchies from social interactions. Yet, there are no clear guidelines about how many observed dominance interactions (i.e. sampling effort) are necessary for inferring reliable dominance hierarchies, nor are there any established tools for quantifying their uncertainty.3.In this study, we simulate interactions (winners and losers) in scenarios of varying steepness (the probability that a dominant defeats a subordinate based on their difference in rank). Using these data, we (1) quantify how the number of interactions recorded and the steepness of the hierarchy affect the performance of five methods for inferring hierarchies, (2) propose an amendment that improves the performance of a popular method, and (3) suggest two easy procedures to measure uncertainty and steepness in the inferred hierarchy.4.We find that the ratio of interactions to individuals required to infer reliable hierarchies is surprisingly low, but depends on the steepness of the hierarchy and the method used. We show that David's score and our novel randomized Elo‐rating are the best methods when hierarchies are not extremely steep, where the original Elo‐rating, the I&SI and the recently described ADAGIO perform less well. In addition, we show that two simple methods can be used to estimate uncertainty at the individual and group level, and that the randomized Elo‐rating repeatability provides researchers with a standardized measure valid for comparing the steepness of different hierarchies. We provide several worked examples to guide researchers interested in studying dominance hierarchies.5.Methods for inferring dominance hierarchies are relatively robust, even when the ratio of observed interactions to individuals is as low as 10 to 20. However, we suggest that implementing simple procedures for estimating uncertainty will benefit researchers, while quantifying the shape of the dominance hierarchy will provide new insights into the social structure of the study organisms.This article is protected by copyright. All rights reserved.
      PubDate: 2017-11-27T08:35:47.595789-05:
      DOI: 10.1111/1365-2656.12776
       
  • Do host‐associated gut microbiota mediate the effect of an herbicide on
           disease risk in frogs'
    • Authors: Sarah A. Knutie; Caitlin R. Gabor, Kevin D. Kohl, Jason R. Rohr
      Abstract: 1.Environmental stressors, such as pollutants, can increase disease risk in wildlife. For example, the herbicide atrazine affects host defenses (e.g. resistance and tolerance) of the amphibian chytrid fungus Batrachochytrium dendrobatidis (Bd), but the mechanisms for these associations are not always clear. Given that pollutants can alter the gut microbiota of hosts, which in turn can affect their health and immune systems, one potential mechanism by which pollutants could increase infection risk is by influencing host‐associated microbiota.2.Here, we test whether early‐life exposure to the estimated environmental concentration (EEC; 200 μg/L) of atrazine affects the gut bacterial composition of Cuban tree frog (Osteopilus septentrionalis) tadpoles and adults and whether any atrazine‐induced change in community composition might affect host defenses against Bd. We also determine whether early‐life changes in the stress hormone corticosterone affect gut microbiota by experimentally inhibiting corticosterone synthesis with metyrapone.3.With the exception of changing the relative abundances of two bacterial genera in adulthood, atrazine did not affect gut bacterial diversity or community composition of tadpoles (in vivo or in vitro) or adults. Metyrapone did not significantly affect bacterial diversity of tadpoles, but significantly increased bacterial diversity of adults.4.Gut bacterial diversity during Bd exposure did not predict host tolerance or resistance to Bd intensity in tadpoles or adults. However, early‐life bacterial diversity negatively predicted Bd intensity as adult frogs. Specifically, Bd intensity as adults was associated negatively with the relative abundance of phylum Fusobacteria in the guts of tadpoles.5.Our results suggest that the effect of atrazine on Bd infection risk is not mediated by host‐associated microbiota because atrazine does not affect microbiota of tadpoles or adults. However, host‐associated microbes seem important in host resistance to Bd because the early‐life microbiota, during immune system development, predicted later‐life infection risk with Bd. Overall, our study suggests that increasing gut bacterial diversity and relative abundances of Fusobacteria might have lasting positive effects on amphibian health.This article is protected by copyright. All rights reserved.
      PubDate: 2017-11-27T08:31:09.366194-05:
      DOI: 10.1111/1365-2656.12769
       
  • Why are tropical mountain passes ‘low’ for some species' Genetic
           and stable‐isotope tests for differentiation, migration, and expansion
           in elevational generalist songbirds
    • Authors: Chauncey R. Gadek; Seth D. Newsome, Elizabeth J. Beckman, Andrea N. Chavez, Spencer C. Galen, Emil Bautista, Christopher C. Witt
      Abstract: 1.Most tropical bird species have narrow elevational ranges, likely reflecting climatic specialization. This is consistent with Janzen's Rule, the tendency for mountain passes to be effectively ‘higher’ in the tropics. Hence, those few tropical species that occur across broad elevational gradients (elevational generalists) represent a contradiction to Janzen's Rule.2.Here we aim to address the following questions. Are elevational generalists being sundered by diversifying selection along the gradient' Does elevational movement cause these species to resist diversification or specialization' Have they recently expanded, suggesting that elevational generalism is short‐lived in geological time'3.To answer these questions, we tested for differentiation, movement, and expansion in four elevational generalist songbird species on the Andean west slope. We used morphology and mtDNA to test for genetic differentiation between high‐ and low‐elevation populations. To test for elevational movements, we measured hydrogen isotope (δ2H) values of metabolically inert feathers and metabolically active liver.4.Morphology differed for House Wren (Troglodytes aedon) and Hooded Siskin (Spinus magellanicus), but not for Cinereous Conebill (Conirostrum cinereum) and Rufous‐collared Sparrow (Zonotrichia capensis), respectively. mtDNA was structured by elevation only in Z. capensis. δ2H data indicated elevational movements by two tree‐ and shrub‐foraging species with moderate‐to‐high vagility (C. cinereum and S. magellanicus), and sedentary behavior by two terrestrial‐foraging species with low‐to‐moderate vagility (T. aedon and Z. capensis). In S. magellanicus, elevational movements and lack of mtDNA structure contrast with striking morphological divergence, suggesting strong diversifying selection on body proportions across the ~50 km gradient. All species except C. cinereum exhibited mtDNA‐haplotype variation consistent with recent population expansion across the elevational gradient, potentially concurrent with Holocene anthropogenic habitat conversion for agriculture.5.In different ways, each species defies the tendency for tropical birds to have long‐term stable distributions and sedentary habits. We conclude that tropical elevational generalism is rare due to evolutionary instability.This article is protected by copyright. All rights reserved.
      PubDate: 2017-11-27T08:31:02.774617-05:
      DOI: 10.1111/1365-2656.12779
       
  • Host effects on microbiota community assembly
    • Authors: Kathrin Näpflin; Paul Schmid-Hempel
      Abstract: 1.To what extent host‐associated microbiota assembly is driven by host selection or simply by happenstance remains an open question in microbiome research.2.Here, we take a first step towards elucidating the relative importance of host selection on the establishing gut microbial community in an ecologically relevant organism.3.We presented germ‐free bumblebee, Bombus terrestris, workers from ten colonies with a “global” microbial species pool comprised of an equal mixture of the gut microbiota of all colonies.4.By means of 16S amplicon sequencing, we found that while overall microbiota community composition was generally shifted between pool‐exposed workers compared to workers that naturally acquired their gut microbiota, but that the specific composition of the established microbiota also depended on colony identity (e.g. genetic background).5.Because the microbiota is protective against parasite infection in this system, variation in the filtering of a beneficial microbial community can have important consequences for host resistance and eventual co‐evolution with parasites.This article is protected by copyright. All rights reserved.
      PubDate: 2017-11-13T05:15:48.961259-05:
      DOI: 10.1111/1365-2656.12768
       
  • Using host species traits to understand the consequences of resource
           provisioning for host–parasite interactions
    • Authors: Daniel J. Becker; Daniel G. Streicker, Sonia Altizer
      Abstract: 1.Supplemental food provided to wildlife by human activities can be more abundant and predictable than natural resources, and subsequent changes to wildlife ecology can have profound impacts on host–parasite interactions. Identifying traits of species associated with increases or decreases in infection outcomes with resource provisioning could improve assessments of wildlife most prone to disease risks in changing environments.2.We conducted a phylogenetic meta‐analysis of 342 host–parasite interactions across 56 wildlife species and three broad taxonomic groups of parasites to identify host‐level traits that influence whether provisioning is associated with increases or decreases in infection.3.We predicted that dietary generalists that capitalize on novel food would show greater infection in provisioned habitats owing to population growth and food‐borne exposure to contaminants and parasite infectious stages. Similarly, species with fast life histories could experience stronger demographic and immunological benefits from provisioning that affect parasite transmission. We also predicted that wide‐ranging and migratory behaviors could increase infection risks with provisioning if concentrated and non‐seasonal foods promote dense aggregations that increase exposure to parasites.4.We found that provisioning increased infection with bacteria, viruses, fungi, and protozoa (i.e., microparasites) most for wide‐ranging, dietary generalist host species. Effect sizes for ectoparasites were also highest for host species with large home ranges but were instead lowest for dietary generalists. In contrast, the type of provisioning was a stronger correlate of infection outcomes for helminths than host species traits.5.Our analysis highlights host traits related to movement and feeding behavior as important determinants of whether species experience greater infection with supplemental feeding. These results could help prioritize monitoring wildlife with particular trait profiles in anthropogenic habitats to reduce infectious disease risks in provisioned populations.This article is protected by copyright. All rights reserved.
      PubDate: 2017-11-13T05:15:39.853121-05:
      DOI: 10.1111/1365-2656.12765
       
  • Understanding the role of parasites in food webs using the group model
    • Authors: Matthew J. Michalska-Smith; Elizabeth L. Sander, Mercedes Pascual, Stefano Allesina
      Abstract: 1.Parasites are ubiquitous and have been shown to influence macroscopic measures of ecological network structure, such as connectance and robustness, as well as local structure, such as subgraph frequencies. Nevertheless, they are often underrepresented in ecological studies due to their small size and often complex life cycles.2.We consider whether or not parasites play structurally unique roles in ecological networks; that is, can we distinguish parasites from other species using network structure alone'3.We partition the species in a community statistically using the group model, and we test whether or not parasites tend to cluster in their own groups, using a measure of “imbalance.”4.We find that parasites form highly imbalanced groups, and that concomitant predation, in which a predator consumes a prey and its parasites, but not the number of interactions, improves the group model's ability to distinguish parasites from non‐parasites.5.This work demonstrates that parasites and non‐parasites interact in networks in statistically distinct ways, and that these differences are partly, but not entirely, due to the existence of concomitant predation.This article is protected by copyright. All rights reserved.
      PubDate: 2017-11-08T21:41:04.488107-05:
      DOI: 10.1111/1365-2656.12782
       
  • Experimental investigation of alternative transmission functions:
           quantitative evidence for the importance of non‐linear transmission
           dynamics in host‐parasite systems
    • Authors: Sarah A. Orlofske; Samuel M. Flaxman, Maxwell B. Joseph, Andy Fenton, Brett A. Melbourne, Pieter T.J. Johnson
      Abstract: 1.Understanding pathogen transmission is crucial for predicting and managing disease. Nonetheless, experimental comparisons of alternative functional forms of transmission remain rare, and those experiments that are conducted are often not designed to test the full range of possible forms.2.To differentiate among ten candidate transmission functions, we used a novel experimental design in which we independently varied four factors—duration of exposure, numbers of parasites, numbers of hosts, and parasite density—in laboratory infection experiments.3.We used interactions between amphibian hosts and trematode parasites as a model system and all candidate models incorporated parasite depletion. An additional manipulation involving anesthesia addressed the effects of host behaviour on transmission form.4.Across all experiments, non‐linear transmission forms involving either a power law or a negative binomial function were the best‐fitting models and consistently outperformed the linear density‐dependent and density‐independent functions. By testing previously published data for two other host‐macroparasite systems, we also found support for the same non‐linear transmission forms.5.Although manipulations of parasite density are common in transmission studies, the comprehensive set of variables tested in our experiments revealed that variation in density alone was least likely to differentiate among competing transmission functions. Across host‐pathogen systems, non‐linear functions may often more accurately represent transmission dynamics and thus provide more realistic predictions for infection.This article is protected by copyright. All rights reserved.
      PubDate: 2017-11-07T06:20:23.819423-05:
      DOI: 10.1111/1365-2656.12783
       
  • Active migration is associated with specific and consistent changes to gut
           microbiota in Calidris shorebirds
    • Authors: Alice Risely; David Waite, Beata Ujvari, Bethany Hoye, Marcel Klaassen
      Abstract: 1.Gut microbes are increasingly recognised for their role in regulating an animal's metabolism and immunity. However, identifying repeatable associations between host physiological processes and their gut microbiota has proved challenging, in part because microbial communities often respond stochastically to host physiological stress (e.g. fasting, forced exercise or infection).2.Migratory birds provide a valuable system in which to test host‐microbe interactions under physiological extremes because these hosts are adapted to predictable metabolic and immunological challenges as they undergo seasonal migrations, including temporary gut atrophy during long‐distance flights. These physiological challenges may either temporarily disrupt gut microbial ecosystems, or, alternatively, promote predictable host‐microbe associations during migration.3.To determine the relationship between migration and gut microbiota, we compared gut microbiota composition between migrating and non‐migrating (‘resident’) conspecific shorebirds sharing a flock. We performed this across two sandpiper species, Calidris ferruginea and Calidris ruficollis, in north‐western Australia, and an additional C. ruficollis population 3000 km away in southern Australia.4.We found that migrants consistently had higher abundances of the bacterial genus Corynebacterium (average 28% abundance) compared to conspecific residents (average < 1% abundance), with this effect holding across both species and sites. However, other than this specific association, community structure and diversity was almost identical between migrants and residents, with migration status accounting for only 1% of gut community variation when excluding Corynebacterium.5.Our findings suggest a consistent relationship between Corynebacterium and Calidris shorebirds during migration, with further research required to identify causal mechanisms behind the association, and to elucidate functionality to the host. However, outside this specific association, migrating shorebirds broadly maintained gut community structure, which may allow them to quickly recover gut function after a migratory flight. This study provides a rare example of a repeatable and specific response of the gut microbiota to a major physiological challenge across two species and two distant populations.This article is protected by copyright. All rights reserved.
      PubDate: 2017-11-07T06:17:16.994462-05:
      DOI: 10.1111/1365-2656.12784
       
  • Resistance and tolerance: the role of nutrients on pathogen dynamics and
           infection outcomes in an insect host
    • Authors: Charlotte V. L. Miller; Sheena C. Cotter
      Abstract: 1.Tolerance and resistance are the two ways in which hosts can lessen the effects of infection. Tolerance aims to minimise the fitness effects resulting from incumbent pathogen populations, whereas resistance aims to reduce the pathogen population size within the host. While environmental impacts on resistance have been extensively recorded their impacts on variation in tolerance are virtually unexplored.2.Here we ask how the environment, namely the host diet, influences the capacity of an organism to tolerate and resist infection, using a model host‐parasite system, the burying beetle, Nicrophorus vespilloides and the entomopathogenic bacteria, Photorhabdus luminescens.3.We first considered dose‐responses and pathogen dynamics within the host, and compared our findings to responses known from other host species. We then investigated how investment in tolerance and resistance changed under different nutritional regimes. Beetles were maintained on one of five diets that varied in their ratio of protein to fat for 48 hours and then injected with P. luminescens. Survival was monitored and the phenoloxidase (PO) response and bacterial load at 24 hours post infection were ascertained.4.The dose required to kill 50% of individuals in this species was several magnitudes higher than in other species and the bacteria were shown to display massive decreases in population size, in contrast to patterns of proliferation found in other host species. Diet strongly modified host survival after infection, with those on the high fat/low protein diet showing 30% survival at 8 days, versus almost 0% survival on the low fat/high protein diet. However, this was independent of bacterial load or variation in PO, providing evidence for diet‐mediated tolerance mechanisms rather than immune‐driven resistance.5.Evolutionary ecology has long focussed on immune resistance when investigating how organisms avoid succumbing to infection. Tolerance of infection has recently become a much more prominent concept and is suggested to be influential in disease dynamics. This is one of the first studies to find diet‐mediated tolerance.This article is protected by copyright. All rights reserved.
      PubDate: 2017-11-01T08:45:27.078192-05:
      DOI: 10.1111/1365-2656.12763
       
  • REVIEW: Dynamic, spatial models of parasite transmission in wildlife:
           their structure, applications, and remaining challenges
    • Authors: Lauren A. White; James D. Forester, Meggan E. Craft
      Abstract: 1.Individual differences in contact rate can arise from host, group, and landscape heterogeneity and can result in different patterns of spatial spread for diseases in wildlife populations with concomitant implications for disease control in wildlife of conservation concern, livestock, and humans. While dynamic disease models can provide a better understanding of the drivers of spatial spread, the effects of landscape heterogeneity have only been modelled in a few well‐studied wildlife systems such as rabies and bovine tuberculosis. Such spatial models tend to be either purely theoretical with intrinsic limiting assumptions or individual‐based models that are often highly species and system specific, limiting the breadth of their utility.2.Our goal was to review studies that have utilized dynamic, spatial models to answer questions about pathogen transmission in wildlife and identify key gaps in the literature. We begin by providing an overview of the main types of dynamic, spatial models (e.g., metapopulation, network, lattice, cellular automata, individual‐based, and continuous‐space) and their relation to each other. We investigate different types of ecological questions that these models have been used to explore: pathogen invasion dynamics and range expansion, spatial heterogeneity and pathogen persistence, the implications of management and intervention strategies, and the role of evolution in host‐pathogen dynamics.3.We reviewed 168 studies that consider pathogen transmission in free‐ranging wildlife and classify them by the model type employed, the focal host‐pathogen system, and their overall research themes and motivation. We observed a significant focus on mammalian hosts, a few well‐studied or purely theoretical pathogen systems, and a lack of studies occurring at the wildlife‐public health or wildlife‐livestock interfaces.4.Finally, we discuss challenges and future directions in the context of unprecedented human‐mediated environmental change. Spatial models may provide new insights into understanding, for example, how global warming and habitat disturbance contribute to disease maintenance and emergence. Moving forward, better integration of dynamic, spatial disease models with approaches from movement ecology, landscape genetics/genomics, and ecoimmunology may provide new avenues for investigation and aid in the control of zoonotic and emerging infectious diseases.This article is protected by copyright. All rights reserved.
      PubDate: 2017-10-22T18:00:25.797266-05:
      DOI: 10.1111/1365-2656.12761
       
  • Novel insights on population and range edge dynamics using an unparalleled
           spatiotemporal record of species invasion
    • Authors: Kristine L. Grayson; Derek M. Johnson
      Abstract: Quantifying the complex spatial dynamics taking place at range edges is critical for understanding future distributions of species, yet very few systems have sufficient data or the spatial resolution to empirically test these dynamics. This paper reviews how data from a large‐scale pest management program have provided important contributions to the fields of population dynamics and invasion biology.The invasion of gypsy moth (Lymantria dispar) is well‐documented from its introduction near Boston, Massachusetts USA in 1869 to its current extent of over 900,000 km2 in Eastern North America. Over the past two decades, the USDA Forest Service Slow the Spread (STS) program for managing the future spread of gypsy moth has produced unrivaled spatiotemporal data across the invasion front.The STS program annually deploys a grid of 60,000 – 100,000 pheromone‐baited traps, currently extending from Minnesota to North Carolina. The data from this program has provided the foundation for investigations of complex population dynamics and the ability to examine ecological hypotheses previously untestable outside of theoretical venues, particularly regarding invasive spread and Allee effects.This system provides empirical data on the importance of long‐distance dispersal and time lags on population establishment and spatial spread. Studies showing high rates of spatiotemporal variation of the range edge, from rapid spread to border stasis and even retraction, highlight future opportunities to test mechanisms that influence both invasive and native species ranges.The STS trap data have also created a unique opportunity to study low‐density population dynamics and quantify Allee effects with empirical data. Notable contributions include evidence for spatiotemporal variation in Allee effects, demonstrating empirical links between Allee effects and spatial spread, and testing mechanisms of population persistence and growth rates at range edges.There remain several outstanding questions in spatial ecology and population biology that can be tested within this system, such as the scaling of local ecological processes to large‐scale dynamics across landscapes. The gypsy moth is an ideal model of how important ecological questions can be answered by thinking more broadly about monitoring data.This article is protected by copyright. All rights reserved.
      PubDate: 2017-10-17T05:07:00.578779-05:
      DOI: 10.1111/1365-2656.12755
       
  • Parasite metacommunities: Evaluating the roles of host community
           composition and environmental gradients in structuring symbiont
           communities within amphibians
    • Authors: Joseph R. Mihaljevic; Bethany J. Hoye, Pieter T. J. Johnson
      Abstract: 1.Ecologists increasingly report the structures of metacommunities for free-living species, yet far less is known about the composition of symbiont communities through space and time. Understanding the drivers of symbiont community patterns has implications ranging from emerging infectious disease to managing host microbiomes.2.Using symbiont communities from amphibian hosts sampled from wetlands of California, USA, we quantified the effects of spatial, habitat filtering, and host community components on symbiont occupancy and overall metacommunity structure.3.We built upon a statistical method to describe metacommunity structure that accounts for imperfect detection in survey data – detection error-corrected elements of metacommunity structure (DECEMS) – by adding an analysis to identify covariates of community turnover. We applied our model to a metacommunity of 8 parasite taxa observed in 3571 Pacific chorus frogs (Pseudacris regilla) surveyed from 174 wetlands over 5 years.4.Symbiont metacommunity structure varied across years, showing nested structure in three years and random structure in two years. Species turnover was most consistently influenced by spatial and host community components. Occupancy generally increased in more southeastern wetlands, and snail (intermediate-host) community composition had strong effects on most symbiont taxa.5.We have used sophisticated but accessible statistical methods to reveal that spatial components - which influence colonization - and host community composition - which mediates transmission - both drive symbiont community composition in this system. These methods allow us to associate broad patterns of community turnover to local, species-level effects, ultimately improving our understanding of spatial community dynamics.This article is protected by copyright. All rights reserved.
      PubDate: 2017-10-04T06:05:53.155032-05:
      DOI: 10.1111/1365-2656.12735
       
  • The index case is not enough: Variation among individuals, groups, and
           social networks modify bacterial transmission dynamics
    • Authors: Carl N. Keiser; Noa Pinter-Wollman, Michael J. Ziemba, Krishna S. Kothamasu, Jonathan N. Pruitt
      Abstract: 1.The traits of the index case of an infectious disease outbreak, and the circumstances for their etiology, potentially influence the trajectory of transmission dynamics. However, these dynamics likely also depend on the traits of the individuals with whom the index case interacts.2.We used the social spider Stegodyphus dumicola to test how the traits of the index case, group phenotypic composition, and group size interact to facilitate the transmission of a GFP-labeled cuticular bacterium. We also compared bacterial transmission across experimentally generated “daisy-chain” versus “star” networks of social interactions. Finally, we compared social network structure across groups of different sizes.3.Groups of 10 spiders experienced more bacterial transmission events compared to groups of 30 spiders, regardless of groups’ behavioral composition. Groups containing only one bold spider experienced the lowest levels of bacterial transmission regardless of group size. We found no evidence for the traits of the index case influencing any transmission dynamics. In a second experiment, bacteria were transmitted to more individuals in experimentally induced star networks than in daisy-chains, on which transmission never exceeded three steps. In both experimental network types, transmission success depended jointly on the behavioral traits of the interacting individuals, however, the behavioral traits of the index case were only important for transmission on star networks.4.Larger social groups exhibited lower interaction density (i.e. had a low ratio of observed to possible connections) and were more modular, i.e., they had more connections between nodes within a sub-group and fewer connections across sub-groups. Thus, larger groups may restrict transmission by forming fewer interactions and by isolating sub-groups that interacted with the index case.5.These findings suggest that accounting for the traits of single exposed hosts has less power in predicting transmission dynamics compared to the larger-scale factors of the social groups in which they reside. Factors like group size and phenotypic composition appear to alter social interaction patterns, which leads to differential transmission of microbes.This article is protected by copyright. All rights reserved.
      PubDate: 2017-09-04T05:22:22.511102-05:
      DOI: 10.1111/1365-2656.12729
       
  • Strategies for managing rival bacterial communities: lessons from burying
           beetles
    • Authors: Ana Duarte; Martin Welch, Chris Swannack, Josef Wagner, Rebecca M. Kilner
      Abstract: 1.The role of bacteria in animal development, ecology and evolution is increasingly well-understood, yet little is known of how animal behaviour affects bacterial communities. Animals that benefit from defending a key resource from microbial competitors are likely to evolve behaviours to control or manipulate the animal's associated external microbiota.2.We describe four possible mechanisms by which animals could gain a competitive edge by disrupting a rival bacterial community: ‘weeding’, ‘seeding’, ‘replanting’ and ‘preserving’. By combining detailed behavioural observations with molecular and bioinformatic analyses, we then test which of these mechanisms best explains how burying beetles, Nicrophorus vespilloides, manipulate the bacterial communities on their carcass breeding resource.3.Burying beetles are a suitable species to study how animals manage external microbiota because reproduction revolves around a small vertebrate carcass. Parents shave a carcass and apply antimicrobial exudates on its surface, shaping it into an edible nest for their offspring. We compared bacterial communities in mice carcasses that were either fresh, prepared by beetles or unprepared but buried underground for the same length of time. We also analysed bacterial communities in the burying beetle's gut, during and after breeding, to understand whether beetles could be ‘seeding’ the carcass with particular microbes.4.We show that burying beetles do not ‘preserve’ the carcass by reducing bacterial load, as is commonly supposed. Instead, our results suggest they ‘seed’ the carcass with bacterial groups which are part of the Nicrophorus core microbiome. They may also ‘replant’ other bacteria from the carcass gut onto the surface of their carrion nest. Both these processes may lead to the observed increase in bacterial load on the carcass surface in the presence of beetles. Beetles may also ‘weed’ the bacterial community by eliminating some groups of bacteria on the carcass, perhaps through the production of antimicrobials themselves.5.Whether these alterations to the bacterial community are adaptive from the beetle's perspective, or are simply a by-product of the way in which the beetles prepare the carcass for reproduction, remains to be determined in future work. In general, our work suggests that animals might use more sophisticated techniques for attacking and disrupting rival microbial communities than is currently appreciated.This article is protected by copyright. All rights reserved.
      PubDate: 2017-08-21T07:31:24.291935-05:
      DOI: 10.1111/1365-2656.12725
       
  • Effects of host species and environment on the skin microbiome of
           Plethodontid salamanders
    • Authors: Carly R. Muletz Wolz; Stephanie A. Yarwood, Evan H. Campbell Grant, Robert C. Fleischer, Karen R. Lips
      Abstract: 1.The amphibian skin microbiome is recognized for its role in defense against pathogens, including the deadly fungal pathogen Batrachochytrium dendrobatidis (Bd). Yet, we have little understanding of evolutionary and ecological processes that structure these communities, especially for salamanders and closely related species. We investigated patterns in the distribution of bacterial communities on Plethodon salamander skin across host species and environments.2.Quantifying salamander skin microbiome structure contributes to our understanding of how host-associated bacteria are distributed across the landscape, among host species, and their putative relationship with disease.3.We characterized skin microbiome structure (alpha-diversity, beta-diversity and bacterial operational taxonomic unit [OTU] abundances) using 16S rRNA gene sequencing for co-occurring Plethodon salamander species (35 P. cinereus, 17 P. glutinosus, 10 P. cylindraceus) at three localities to differentiate the effects of host species from environmental factors on the microbiome. We sampled the microbiome of P. cinereus along an elevational gradient (n = 50, 700 – 1000 masl) at one locality to determine whether elevation predicts microbiome structure. Finally, we quantified prevalence and abundance of putatively anti-Bd bacteria to determine if Bd-inhibitory bacteria are dominant microbiome members.4.Co-occurring salamanders had similar microbiome structure, but among sites salamanders had dissimilar microbiome structure for beta-diversity and abundance of 28 bacterial OTUs. We found that alpha-diversity increased with elevation, beta-diversity and the abundance of 17 bacterial OTUs changed with elevation (16 OTUs decreasing, 1 OTU increasing). We detected 11 putatively anti-Bd bacterial OTUs that were present on 90% of salamanders and made up an average relative abundance of 83% (SD ± 8.5) per salamander. All salamanders tested negative for Bd.5.We conclude that environment is more influential in shaping skin microbiome structure than host differences for these congeneric species, and suggest that environmental characteristics that co-vary with elevation influence microbiome structure. High prevalence and abundance of anti-Bd bacteria may contribute to low Bd levels in these populations of Plethodon salamanders.This article is protected by copyright. All rights reserved.
      PubDate: 2017-08-21T07:30:28.22075-05:0
      DOI: 10.1111/1365-2656.12726
       
  • The microbiota of diapause: how host-microbe associations are formed after
           dormancy in an aquatic crustacean
    • Authors: Alexandra A. Mushegian; Jean-Claude Walser, Karen E. Sullam, Dieter Ebert
      Abstract: 1.A critical question in symbiosis research is where and how organisms obtain beneficial microbial symbionts in different ecological contexts. Microbiota of juveniles are often derived directly from their mother or from the immediate environment. The origin of beneficial symbionts, however, is less obvious in organisms with diapause and dispersal stages, such as plants with dormant seeds and animals in ephemeral or strongly seasonal habitats. In these cases, parents and offspring are separated in time and space, which may affect opportunities for both vertical and horizontal transmission of symbionts.2.The planktonic crustacean Daphnia produces long-lasting resting eggs to endure winter freezing and summer droughts and requires microbiota for growth and reproduction. It is unknown how hatchlings from resting stages form associations with microbial consorts after diapause.3.Using natural samples of D. magna resting eggs after several years of storage, we show that the total bacterial community derived from both the exterior and interior of the eggs’ ephippial cases is sufficiently beneficial to ensure normal Daphnia functioning in otherwise bacteria-free conditions. We do not find direct evidence that the required bacteria are of maternal origin, though sequencing reveals that the resting stage is accompanied by bacterial taxa previously found in association with adult animals.4.These findings suggest that while Daphnia are strongly dependent on environmental bacteria for normal functioning, host-bacteria associations are somewhat general and availability of specific bacteria is not a strong constraint on host ecology. Nevertheless, animals and microbes may be ecologically linked through co-dispersal.This article is protected by copyright. All rights reserved.
      PubDate: 2017-07-17T05:00:42.970575-05:
      DOI: 10.1111/1365-2656.12709
       
  • Parasite-microbiota interactions potentially affect intestinal communities
           in wild mammals
    • Authors: Tuomas Aivelo; Anna Norberg
      Abstract: 1.Detecting interaction between species is notoriously difficult, and disentangling species associations in host-related gut communities is especially challenging. Nevertheless, due to contemporary methods, including metabarcoding and 16S sequencing, collecting observational data on community composition has become easier and much more common.2.We studied the previously collected data sets of intestinal bacterial microbiota and parasite compositions within longitudinally followed mouse lemurs by analysing the potential interactions with diversity metrics and novel joint species distribution modelling.3.Both methods showed statistical association between certain parasite species and bacterial microbiota composition. Unicellular Eimeria sp. had an effect on diversity of gut microbiota. The cestode Hymenolepis diminuta had negative associations with several bacterial orders, whereas closely related species H. nana had positive associations with several bacterial orders.4.Our results reveal potential interactions between some, but not all, intestinal parasites and gut bacterial microbiota. Host variables contributed over half of the total variation explained with the model, and sex was the most important single host variable; especially with microbiota, there were sex-related differences in the community composition.5.This study shows how joint species distribution modelling can incorporate both within-host dynamics of several taxa and host characteristics to model potential interactions in intestinal community. These results provide new hypothesis for interactions between and among parasites and bacterial microbiota to be tested further with experimental studies.This article is protected by copyright. All rights reserved.
      PubDate: 2017-07-03T04:21:19.286627-05:
      DOI: 10.1111/1365-2656.12708
       
  • Consequences of symbiont co-infections for insect host phenotypes
    • Authors: Ailsa H. C. McLean; Benjamin J. Parker, Jan Hrček, James C. Kavanagh, Peter A. D. Wellham, H. Charles J. Godfray
      Abstract: 1.Most animals host communities of symbiotic bacteria. In insects, these symbionts may have particularly intimate interactions with their hosts: many are intracellular and can play important roles in host ecology and evolution, including protection against natural enemies.2.We investigated how interactions between different species or strains of endosymbiotic bacteria within an aphid host influence the outcome of symbiosis for both symbiont and host.3.We first asked whether different combinations of facultative symbiont species or strains can exist in stable co-infections. We then investigated whether the benefits that facultative bacteria confer on their hosts (protection against natural enemies) are enhanced, reduced or unaltered by the presence of a co-infecting symbiont. We asked this both for co-infecting symbionts that confer different phenotypes on their hosts (protection against fungal pathogens vs. parasitoid wasps) and symbionts with overlapping functions. Finally, we investigated the additional survival costs to aphids of carrying multiple infections of symbiont species or strains, and compared symbiont titres in double and single infections.4.We found that stable co-infections were possible between all of the combinations of facultative symbiont species (Regiella insecticola + Hamiltonella defensa, Regiella + Rickettsiella sp., Regiella + Spiroplasma sp.) and strains (Hamiltonella) that we studied. Where symbionts provided protection against different natural enemies, no alteration in protection was observed in the presence of co-infections. Where symbionts provided protection against the same natural enemy, the level of protection corresponded to the higher of the two symbionts present. In some instances, aphid hosts suffered additional survival costs when hosting double infections. In the case of Hamiltonella, however, infection with multiple strains of the same symbiont led to lower symbiont titres than single infections, and actually improved aphid survival.5.We conclude that the long-term maintenance of symbiont co-infections in aphids is likely to be determined primarily by costs of co-infections and in some instances by redundancy of symbiont benefits.This article is protected by copyright. All rights reserved.
      PubDate: 2017-07-03T04:20:23.102587-05:
      DOI: 10.1111/1365-2656.12705
       
  • Gut microbial communities of American pikas (Ochotona princeps): evidence
           for phylosymbiosis and adaptations to novel diets
    • Authors: Kevin D. Kohl; Johanna Varner, Jennifer L. Wilkening, M. Denise Dearing
      Abstract: 1.Gut microbial communities provide many physiological functions to their hosts, especially in herbivorous animals. We still lack an understanding of how these microbial communities are structured across hosts in nature, especially within a given host species. Studies on laboratory mice have demonstrated that host genetics can influence microbial community structure, but that diet can overwhelm these genetic effects.2.We aimed to test these ideas in a natural system, the American pika (Ochotona princeps). First, pikas are high elevation specialists with significant population structure across various mountain ranges in the USA, allowing us to investigate whether similarities in microbial communities match host genetic differences. Additionally, pikas are herbivorous, with some populations exhibiting remarkable dietary plasticity and consuming high levels of moss, which is exceptionally high in fiber and low in protein. This allows us to investigate adaptations to an herbivorous diet, as well as to the especially challenging diet of moss.3.Here, we inventoried the microbial communities of pika cecal pellets from various populations using 16S rRNA sequencing to investigate structuring of microbial communities across various populations with different natural diets.4.Microbial communities varied significantly across populations, and similarities in microbial community structure were congruent with genetic differences in host population structure, a pattern known as ‘phylosymbiosis’.5.Several microbial members (Ruminococcus, Prevotella, Oxalobacter, Coprococcus) were detected across all samples, and thus likely represent a ‘core microbiome’. These genera are known to perform a number of services for herbivorous hosts such as fiber fermentation and the degradation of plant defensive compounds, and thus are likely important for herbivory in pikas. Moreoever, populations of pikas that feed on moss harbored microbial communities highly enriched in Melainabacteria. This uncultivable candidate phylum has been proposed to ferment fiber for herbivores, and thus may contribute to the ability of some pika populations to consume high amounts of moss.6.These findings demonstrate that both host genetics and diet can influence the microbial communities of the American pika. These animals may be novel sources of fiber-degrading microbes. Last, we discuss the implications of population-specific microbial communities for conservation efforts in this species.This article is protected by copyright. All rights reserved.
      PubDate: 2017-06-26T03:33:10.956297-05:
      DOI: 10.1111/1365-2656.12692
       
  • Queen presence mediates the relationship between collective behavior and
           disease susceptibility in ant colonies
    • Authors: Carl N. Keiser; Svjetlana Vojvodic, Imani O. Butler, Elizabeth Sartain, Volker H. W. Rudolf, Julia B. Saltz
      Abstract: The success of social living can be explained, in part, by a group's ability to execute collective behaviors unachievable by solitary individuals. However, groups vary in their ability to execute these complex behaviors, often because they vary in their phenotypic composition. Group membership changes over time due to mortality or emigration, potentially leaving groups vulnerable to ecological challenges in times of flux. In some societies, the loss of important individuals (e.g., leaders, elites, queens) may have an especially detrimental effect on groups’ ability to deal with these challenges.Here, we test whether the removal of queens in colonies of the acorn ant Temnothorax curvispinosus alters their ability to execute important collective behaviors and survive outbreaks of a generalist entomopathogen.We employed a split-colony design where one half of a colony was maintained with its queen, while the other half was separated from the queen. We then tested these subcolonies’ performance in a series of collective behavior assays and finally exposed colonies to the entomopathogenic fungus Metarhizium robertsii by exposing two individuals from the colony and then sealing them back into the nest.We found that queenright subcolonies outperformed their queenless counterparts in nearly all collective behaviors. Queenless subcolonies were also more vulnerable to mortality from disease. However, queenless groups that displayed more interactions with brood experienced greater survivorship, a trend not present in queenright subcolonies. Queenless subcolonies that engage in more brood interactions may have had more resources available to cope with two physiological challenges (ovarian development after queen loss and immune activation after pathogen exposure).Our results indicate that queen presence can play an integral role in colony behavior, survivorship, and their relationship. They also suggest that interactions between workers and brood are integral to colonies survival. Overall, a social group's history of social reorganization may have strong consequences on their collective behaviors and their vulnerability to disease outbreaks.This article is protected by copyright. All rights reserved.
      PubDate: 2017-06-22T04:16:07.517986-05:
      DOI: 10.1111/1365-2656.12696
       
  • Multi-modal defenses in aphids offer redundant protection and increased
           costs likely impeding a protective mutualism
    • Authors: Adam J. Martinez; Matthew R. Doremus, Laura J. Kraft, Kyungsun L. Kim, Kerry M. Oliver
      Abstract: 1.The pea aphid, Acyrthosiphon pisum, maintains extreme variation in resistance to its most common parasitoid wasp enemy, Aphidius ervi, which is sourced from two known mechanisms: protective bacterial symbionts, most commonly Hamiltonella defensa, or endogenously encoded defenses. We have recently found that individual aphids may employ each defense individually, occasionally both defenses together, or neither.2.In field populations, Hamiltonella-infected aphids are found at low to moderate frequencies and while less is known about the frequency of resistant genotypes, they show up less often than susceptible genotypes in field collections. To better understand these patterns, we sought to compare the strengths and costs of both types of defense, individually and together, in order to elucidate the selective pressures that maintain multi-modal defense mechanisms or that may favor one over the other.3.We experimentally infected five aphid genotypes (two lowly and three highly resistant), each with two symbiont strains, Hamiltonella-APSE8 (moderate protection) and Hamiltonella-APSE3 (high protection). This resulted in three sublines per genotype: uninfected, +APSE8, and +APSE3. Each of the fifteen total sublines was first subjected to a parasitism assay to determine its resistance phenotype and in a second experiment a subset were chosen to compare fitness (fecundity and survivorship) in presence and absence of parasitism.4.In susceptible aphid genotypes, parasitized sublines infected with Hamiltonella generally showed increased protection with direct fitness benefits, but clear infection costs to fitness in the absence of parasitism. In resistant genotypes, Hamiltonella infection rarely conferred additional protection, often further reduced fecundity and survivorship when enemy challenged, and resulted in constitutive fitness costs in the absence of parasitism. We also identified strong aphid-genotype X symbiont-strain interactions, such that the best defensive strategy against parasitoids varied for each aphid genotype; one performed best with no protective symbionts, the others with particular strains of Hamiltonella.5.This surprising variability in outcomes helps explain why Hamiltonella infection frequencies are often intermediate and do not strongly track parasitism frequencies in field populations. We also find that variation in endogenous traits, such as resistance, among host genotypes may offer redundancy and generally limit the invasion potential of mutualistic microbes in insects.This article is protected by copyright. All rights reserved.
      PubDate: 2017-04-05T02:35:41.575759-05:
      DOI: 10.1111/1365-2656.12675
       
  • Density-dependent selection on mate search and evolution of Allee effects
    • Authors: Luděk Berec; Andrew M. Kramer, Veronika Bernhauerová, John M. Drake
      Abstract: Sexually reproducing organisms require males and females to find each other. Increased difficulty of females finding mates as male density declines is the most frequently reported mechanism of Allee effects in animals. Evolving more effective mate search may alleviate Allee effects, but may depend on density regimes a population experiences. In particular, high density populations may evolve mechanisms that induce Allee effects which become detrimental when populations are reduced and maintained at a low density.We develop an individual-based, eco-genetic model to study how mating systems and fitness trade-offs interact with changes in population density to drive evolution of the rate at which males or females search for mates. Finite mate search rate triggers Allee effects in our model and we explore how these Allee effects respond to such evolution.We allow a population to adapt to several population density regimes and examine whether high-density populations are likely to reverse adaptations attained at low densities. We find density-dependent selection in most of scenarios, leading to search rates that result in lower Allee thresholds in populations kept at lower densities. This mainly occurs when fecundity costs are imposed on mate search, and provides an explanation for why Allee effects are often observed in anthropogenically rare species.Optimizing selection, where the attained trait value minimizes the Allee threshold independent of population density, depended on the trade-off between search and survival, combined with monogamy when females were searching. Other scenarios led to runaway selection on the mate search rate, including evolutionary suicide. Trade-offs involved in mate search may thus be crucial to determining how density influences the evolution of Allee effects.Previous studies did not examine evolution of a trait related to the strength of Allee effects under density variation. We emphasize the crucial role that mating systems, fitness trade-offs, and the evolving sex have in determining the density threshold for population persistence, in particular since evolution need not always take the Allee threshold to its minimum value.This article is protected by copyright. All rights reserved.
      PubDate: 2017-02-27T05:07:24.476946-05:
      DOI: 10.1111/1365-2656.12662
       
  • Immune priming specificity within and across generations reveals the range
           of pathogens affecting evolution of immunity in an insect
    • Authors: Julien Dhinaut; Manon Chogne, Yannick Moret
      Abstract: 1.Many organisms can improve their immune response as a function of their immunological experience or that of their parents. This phenomenon, called immune priming, has likely evolved from repetitive challenges by the same pathogens during the host lifetime or across generation.2.All pathogens may not expose host to the same probability of re-infection and immune priming is expected to evolve from pathogens exposing the host to the greatest probability of re-infection. Under this hypothesis, the priming response to these pathogens should be specifically more efficient and less costly than to others.3.We examined the specificity of immune priming within and across generations in the mealworm beetle, Tenebrio molitor, by comparing survival of individuals to infection with bacteria according to their own immunological experience or that of their mother with these bacteria.4.We found that insects primed with Gram-positive bacteria became highly protected against both Gram-positive and Gram-negative bacterial infections, mainly due to an induced persistent antibacterial response, which did not exist in insects primed with Gram-negative bacteria. Insects primed with Gram-positive bacteria also exhibited enhanced concentration of hemocytes, but their implication in acquired resistance was not conclusive because of the persistent antibacterial activity in the hemolymph. Offspring maternally primed with Gram-positive and Gram-negative bacteria exhibited similarly improved immunity, whatever the bacteria used for the infection. Such maternal protection was costly in the larval development of offspring, but this cost was lower for offspring maternally primed with Gram-positive bacteria.5.While T. molitor can develop some levels of primed response to Gram-negative bacteria, the priming response to Gram-positive bacteria was more efficient and less costly. We concluded that Gram-positive bacterial pathogens were of paramount importance in the evolution of immune priming in this insect species.This article is protected by copyright. All rights reserved.
      PubDate: 2017-02-27T05:00:22.430441-05:
      DOI: 10.1111/1365-2656.12661
       
  • Sex Differences and Allee Effects Shape the Dynamics of Sex-Structured
           Invasions
    • Authors: Allison K. Shaw; Hanna Kokko, Michael G. Neubert
      Abstract: SummaryThe rate at which a population grows and spreads can depend on individual behaviour and interactions with others. In many species with two sexes, males and females differ in key life history traits (e.g. growth, survival, dispersal), which can scale up to affect population rates of growth and spread. In sexually reproducing species, the mechanics of locating mates and reproducing successfully introduce further complications for predicting the invasion speed (spread rate), as both can change nonlinearly with density.Most models of population spread are based on one sex, or include limited aspects of sex differences. Here we ask whether and how the dynamics of finding mates interact with sex-specific life history traits to influence the rate of population spread.We present a hybrid approach for modelling invasions of populations with two sexes that links individual-level mating behaviour (in an individual-based model) to population-level dynamics (in an integrodifference equation model).We find that limiting the amount of time during which individuals can search for mates causes a demographic Allee effect which can slow, delay or even prevent an invasion. Furthermore, any sex-based asymmetries in life history or behaviour (skewed sex ratio, sex-biased dispersal, sex-specific mating behaviours) amplify these effects. In contrast, allowing individuals to mate more than once ameliorates these effects, enabling polygynandrous populations to invade under conditions where monogamously mating populations would fail to establish.We show that details of individuals’ mating behaviour can impact the rate of population spread. Based on our results, we propose a stricter definition of a mate-finding Allee effect, which is not met by the commonly used minimum mating function. Our modelling approach, which links individual and population-level dynamics in a single model, may be useful for exploring other aspects of individual behaviour that are thought to impact the rate of population spread.This article is protected by copyright. All rights reserved.
      PubDate: 2017-02-20T21:55:22.697351-05:
      DOI: 10.1111/1365-2656.12658
       
  • Transparency and open processes in Journal of Animal Ecology
    • Authors: Kenneth Wilson; Ben C. Sheldon, Jean-Michel Gaillard, Nathan J. Sanders, Simon P. G. Hoggart, Erika Newton
      First page: 1
      PubDate: 2017-12-13T04:46:01.519234-05:
      DOI: 10.1111/1365-2656.12785
       
  • The mechanistic basis of demographic Allee effects: The search for mates
    • Authors: Anna Kuparinen
      First page: 4
      Abstract: In Focus: Berec, L., Kremer, A.M., Bernhauverova, V., & Drake, J.M. (2017). Density‐dependent selection on mate‐finding Allee effects. Journal of Animal Ecology, 87, 24–35. https://doi.org/10.1111/1365-2656.12662In Focus: Shaw, A.K., Kokko, H., & Neubert, M.G. (2017). Details of mate finding drive dynamics of sex structured invasions. Journal of Animal Ecology, 87, 36–46. https://doi.org/10.1111/1365-2656.12658Lowered population growth ability at low abundances is called the demographic Allee effect. The difficulty of finding mates in a sparse population is the best documented pathway through which a demographic Allee effect might arise. The articles in focus here aim to establish the mechanistic links between mate search component Allee effects and the emergent demographic Allee effect manifested at the level of population growth rate. The authors discover that limitations in the time invested in mate searching generates demographic Allee effects and that the population level adaptations of mate search time are likely to be dependent on the prevailing population density. Trade‐offs between mate search, survival and reproductive outputs are key in understanding optimal mate search strategies and their fitness consequences. The present studies provide guidelines to identify populations at risk of experiencing demographic Allee effects at low abundances.Population growth ability can reduce at low abundances, increasing the risk of extinction. Two papers in the current issue demonstrate how this might occur in response to difficulties individuals experience in finding mates. Evolutionary adaptation to the number of mates in dense populations makes them particularly vulnerable to rapid declines.
      PubDate: 2017-12-13T04:46:01.343316-05:
      DOI: 10.1111/1365-2656.12774
       
  • Editorial: Allee effects in ecology and evolution
    • Authors: Andrew M. Kramer; Luděk Berec, John M. Drake
      First page: 7
      PubDate: 2017-12-13T04:45:55.80611-05:0
      DOI: 10.1111/1365-2656.12777
       
  • Allee Effects in Social Species
    • Authors: Elena Angulo; Gloria M. Luque, Stephen D. Gregory, John W. Wenzel, Carmen Bessa-Gomes, Ludek Berec, Franck Courchamp
      First page: 47
      Abstract: Allee effects have important implications for many aspects of basic and applied ecology. The benefits of aggregation of conspecific individuals are central to Allee effects, which have led to the widely held assumption that social species are more prone to Allee effects. Robust evidence for this assumption, however, remains rare. Further, previous research on Allee effects has failed to adequately address the consequences of the different levels of organization within social species’ populations.Here, we review available evidence of Allee effects and model the role of demographic and behavioural factors that may combine to dampen or strengthen Allee effects in social species. We use examples across various species with contrasting social structure, including carnivores, bats, primates, and eusocial insects. Building on this, we provide a conceptual framework that allows for the integration of different Allee effects in social species.Social species are characterised by nested levels of organisation. The benefits of cooperation, measured by mean individual fitness, can be observed at both the population and group levels, giving rise to “population level” and “group level” Allee effects, respectively. We also speculate on the possibility of a third level, reporting per capita benefits for different individuals within a group (e.g., castes in social insects).We show that group size heterogeneity and intergroup interactions affect the strength of population level demographic Allee effects. Populations with higher group size heterogeneity and in which individual social groups cooperate demonstrate the weakest Allee effects and may thus provide an explanation for why extinctions due to Allee effects are rare in social species.More adequately accounting for Allee effects in social species will improve our understanding of the ecological and evolutionary implications of cooperation in social species.This article is protected by copyright. All rights reserved.
      PubDate: 2017-11-06T05:37:16.746505-05:
      DOI: 10.1111/1365-2656.12759
       
  • A cascade of destabilizations: combining Wolbachia and Allee effects to
           eradicate insect pests
    • Authors: Julie C. Blackwood; Roger Vargas, Xavier Fauvergue
      First page: 59
      Abstract: 1.The management of insect pests has long been dominated by the use of chemical insecticides, with the aim of instantaneously killing enough individuals to limit their damage. To minimize unwanted consequences, environmentally friendly approaches have been proposed that utilize biological control and take advantage of intrinsic demographic processes to reduce pest populations.2.We address the feasibility of a novel pest management strategy based on the release of insects infected with Wolbachia, which causes cytoplasmic incompatibilities in its host population, into a population with a pre‐existing Allee effect. We hypothesize that the transient decline in population size caused by a successful invasion of Wolbachia can bring the population below its Allee threshold and, consequently, trigger extinction.3.We develop a stochastic population model that accounts for Wolbachia‐induced cytoplasmic incompatibilities in addition to an Allee effect arising from mating failures at low population densities. Using our model, we identify conditions under which cytoplasmic incompatibilities and Allee effects successfully interact to drive insect pest populations toward extinction. Based on our results, we delineate control strategies based on introductions of Wolbachia‐infected insects.4.We extend this analysis to evaluate control strategies that implement successive introductions of two incompatible Wolbachia strains. Additionally, we consider methods that combine Wolbachia invasion with mating disruption tactics to enhance the pre‐existing Allee effect.5.We demonstrate that Wolbachia‐induced cytoplasmic incompatibility and the Allee effect act independently from one another: the Allee effect does not modify the Wolbachia‐invasion threshold, and cytoplasmic incompatibilities only have a marginal effect on the Allee threshold. However, the interaction of these two processes can drive even large populations to extinction. The success of this method can be amplified by the introduction of multiple Wolbachia cytotypes as well as the addition of mating disruption.6.Our study extends the existing literature by proposing the use of Wolbachia introductions to capitalize on pre‐existing Allee effects and consequently eradicate insect pests. More generally, it highlights the importance of transient dynamics, and the relevance of manipulating a cascade of destabilizatons for pest management.This article is protected by copyright. All rights reserved.
      PubDate: 2017-10-23T06:16:01.616494-05:
      DOI: 10.1111/1365-2656.12756
       
  • Differential Dispersal and the Allee Effect Create Power-Law Behavior:
           Distribution of Spot Infestations During Mountain Pine Beetle Outbreaks
    • Authors: James A. Powell; Martha J. Garlick, Barbara J. Bentz, Nicholas Friedenberg
      First page: 73
      Abstract: Mountain pine beetles (MPB, Dendroctonus ponderosae Hopkins) are aggressive insects attacking Pinus host trees. Pines use defensive resin to overwhelm attackers, creating an Allee effect requiring beetles to attack en masse to successfully reproduce. MPB kill hosts, leaving observable, dying trees with red needles. Landscape patterns of infestation depend on MPB dispersal, which decreases with host density. Away from contiguously impacted patches (low beetle densities), infestations are characterized by apparently random spots (of 1-10 trees).It remains unclear whether the new spots are spatially random eruptions of a locally endemic population or a mode of MPB spread, with spatial distribution determined by beetle motility and the need to overcome the Allee effect.To discriminate between the hypothesis of population spread versus independent eruption, a model of spot formation by dispersing beetles facing a local Allee effect is derived. The model gives rise to an inverse power distribution of travel times from existing outbreaks. Using landscape-level host density maps in three study areas, an independently-calibrated model of landscape resistance depending on host density, and aerial detection surveys, we calculated yearly maps of travel time to previous beetle impact. Isolated beetle spots were sorted by travel time and compared with predictions. Random eruption of locally endemic populations was tested using artificially-seeded spots. We also evaluated the relationship between number of new spots and size of the perimeter of previously infested areas.Spot distributions conformed strongly to predicted power-law behavior. The spatially random eruption hypothesis was found to be highly improbable. Spot numbers grew consistently with perimeter of previously infested area, suggesting that MPB spread long distances from the boundary via spots following an inverse power distribution.The Allee effect in MPB therefore accelerates, rather than limits, invasion rates, contributing to recent widespread landscape-scale mortality in western North America. This article is protected by copyright. All rights reserved.
      PubDate: 2017-06-26T09:13:17.362422-05:
      DOI: 10.1111/1365-2656.12700
       
  • Using experimentation to understand the 10-year snowshoe hare cycle in the
           boreal forest of North America
    • Authors: Charles J. Krebs; Rudy Boonstra, Stan Boutin
      First page: 87
      Abstract: Population cycles have long fascinated ecologists from the time of Charles Elton in the 1920s. The discovery of large population fluctuations in undisturbed ecosystems challenged the idea that pristine nature was in a state of balance. The 10-year cycle of snowshoe hares (Lepus americanus Erxleben) across the boreal forests of Canada and Alaska is a classic cycle, recognized by fur traders for more than 300 years.Since the 1930s ecologists have investigated the mechanisms that might cause these cycles. Proposed causal mechanisms have varied from sunspots to food supplies, parasites, diseases, predation, and social behaviour. Both the birth rate and the death rate change dramatically over the cycle. Social behaviour was eliminated as a possible cause because snowshoe hares are not territorial and do not commit infanticide.Since the 1960s large-scale manipulative experiments have been used to discover the major limiting factors. Food supply and predation quickly became recognized as potential key factors causing the cycle. Experiments adding food and restricting predator access to field populations have been decisive in pinpointing predation as the key mechanism causing these fluctuations.The immediate cause of death of most snowshoe hares is predation by a variety of predators, including the Canada lynx (Lynx canadensis Kerr). The collapse in the reproductive rate is not due to food shortage as was originally thought, but is a result of chronic stress from predator chases.Five major issues remain unresolved. First, what is the nature of the predator-induced memory that results in the prolonged low phase of the cycle' Second, why do hare cycles form a travelling wave, starting in the centre of the boreal forest in Saskatchewan and travelling across western Canada and Alaska' Third, why does the amplitude of the cycle vary greatly from one cycle to the next in the same area' Fourth, do the same mechanisms of population limitation apply to snowshoe hares in eastern North American or in similar ecosystems across Siberia' Finally, what effect will climatic warming have on all the above issues' The answers to these questions remain for future generations of biologists to determine.This article is protected by copyright. All rights reserved.
      PubDate: 2017-07-24T06:12:23.322997-05:
      DOI: 10.1111/1365-2656.12720
       
  • Wildlife disease ecology from the individual to the population: insights
           
    • Authors: Jenni L. McDonald; Andrew Robertson, Matthew J. Silk
      First page: 101
      Abstract: 1. Long-term individual-based datasets on host-pathogen systems are a rare and valuable resource for understanding the infectious disease dynamics in wildlife. A study of European badgers (Meles meles) naturally infected with bovine tuberculosis (bTB) at Woodchester Park in Gloucestershire (UK) has produced a unique dataset, facilitating investigation of a diverse range of epidemiological and ecological questions with implications for disease management.2. Since the 1970s this badger population has been monitored with a systematic mark-recapture regime yielding a dataset of >15,000 captures of >3000 individuals, providing detailed individual life-history, morphometric, genetic, reproductive and disease data.3. The annual prevalence of bTB in the Woodchester Park badger population exhibits no straightforward relationship with population density, and both the incidence and prevalence of M. bovis shows marked variation in space. The study has revealed phenotypic traits that are critical for understanding the social structure of badger populations along with mechanisms vital for understanding disease spread at different spatial resolutions.4. Woodchester-based studies have provided key insights into how host ecology can influence infection at different spatial and temporal scales. Specifically, it has revealed heterogeneity in epidemiological parameters; intrinsic and extrinsic factors affecting population dynamics; provided insights into senescence and individual life-histories; and revealed consistent individual variation in foraging patterns, refuge use and social interactions.5. An improved understanding of ecological and epidemiological processes is imperative for effective disease management. Woodchester Park research has provided information of direct relevance to bTB management, and a better appreciation of the role of individual heterogeneity in disease transmission can contribute further in this regard.6. The Woodchester Park study system now offers a rare opportunity to seek a dynamic understanding of how individual-, group- and population-level processes interact. The wealth of existing data makes it possible to take a more integrative approach to examining how the consequences of individual heterogeneity scale to determine population-level pathogen dynamics, and help advance our understanding of the ecological drivers of host-pathogen systems.This article is protected by copyright. All rights reserved.
      PubDate: 2017-09-28T05:00:56.102254-05:
      DOI: 10.1111/1365-2656.12743
       
  • An evolutionary framework outlining the integration of individual social
           and spatial ecology
    • Authors: Quinn M. R. Webber; Eric Vander Wal
      First page: 113
      Abstract: 1.Behaviour is the interface between an organism and its environment, and behavioural plasticity is important for organisms to cope with environmental change. Social behaviour is particularly important because sociality is a dynamic process, where environmental variation influences group dynamics and social plasticity can mediate resource acquisition. Heterogeneity in the ecological environment can therefore influence the social environment. The combination of the ecological and social environments may be interpreted collectively as the ‘socioecological’ environment’, which could explain variation in fitness.2.Our objective was to outline a framework through which individual social and spatial phenotypes can be integrated and interpreted as phenotypes that covary as a function of changes in the socioecological environment. We propose the socioecological environment is composed of individual behavioural traits, including sociality and habitat selection, both of which are repeatable, potentially heritable, and may reflect animal personality traits. We also highlight how ecological and social niche theory can be applied to the socioecological environment framework, where individuals occupy different socioecological niches. Individual sociality and habitat selection are also density‐dependent, and theory predicts that density‐dependent traits should affect reproduction, survival, and therefore fitness and population dynamics.3.We then illustrate the proximate links between sociality, habitat selection, and fitness as well as the ultimate, and possibly adaptive, consequences associated with changes in population density. The ecological, evolutionary, and applied implications of our proposed socioecological environment framework are broad and changes in density could influence individual fitness and population dynamics. For instance, human induced environmental changes can influence population density, which can affect the distribution of social and spatial phenotypes within a population. In summary, we outline a conceptual framework that incorporates individual social and spatial behavioural traits with fitness and we highlight a range of ecological and evolutionary processes that are likely associated with the socioecological environment.This article is protected by copyright. All rights reserved.
      PubDate: 2017-11-27T08:30:33.695757-05:
      DOI: 10.1111/1365-2656.12773
       
  • When to choose dynamic versus static social network analysis
    • Authors: Damien R. Farine
      First page: 128
      Abstract: 1.There is increasing interest in using dynamic social networks in the study of animal sociality and its consequences. However, there is a general lack of guidance on the when and how such an approach will be valuable.2.The aim of this paper is to provide a guide on when to choose dynamic versus static social network analysis, and how to choose the appropriate temporal scale for the dynamic network.3.I first discuss the motivations for using dynamic animal social networks. I then provide guidance on how to choose between dynamic networks and the ‘standard’ approach of using static networks. I discuss this in the context of the temporal scale of changes observed, of their predictability, and of the data availability.4.Dynamic networks are important in a number of scenarios. First, if the network data are being compared to independent processes, such as the spread of information or disease or environmental changes, then dynamics networks will provide more accurate estimates of spreading rates. Second, if the network has predictable patterns of change, for example diel cycles or seasonal changes, then dynamic networks should be used to capture these changes. Third, dynamic networks are important for studies of spread through networks when the relationship between edge weight and transmission probability is non‐linear. Finally, dynamic social networks are also useful in situations where interactions among individuals are dense, such as in studies of captive groups.5.The use of static versus dynamic network requires careful consideration, both from a research question perspective and from a data perspective, and this paper provides a guide on how to evaluate the relative importance of these.This article is protected by copyright. All rights reserved.
      PubDate: 2017-11-02T06:50:41.752954-05:
      DOI: 10.1111/1365-2656.12764
       
  • Desynchronizations in bee-plant interactions cause severe fitness losses
           in solitary bees
    • Authors: Mariela Schenk; Jochen Krauss, Andrea Holzschuh
      First page: 139
      Abstract: 1.Global warming can disrupt mutualistic interactions between solitary bees and plants when increasing temperature differentially changes the timing of interacting partners. One possible scenario is for insect phenology to advance more rapidly than plant phenology.2.However, empirical evidence for fitness consequences due to temporal mismatches is lacking for pollinators and it remains unknown if bees have developed strategies to mitigate fitness losses following temporal mismatches.3.We tested the effect of temporal mismatches on the fitness of three spring-emerging solitary bee species, including one pollen specialist. Using flight cages, we simulated (i) a perfect synchronization (from a bee perspective): bees and flowers occur simultaneously, (ii) a mismatch of three days and (iii) a mismatch of six days, with bees occurring earlier than flowers in the latter two cases.4.A mismatch of six days caused severe fitness losses in all three bee species, as few bees survived without flowers. Females showed strongly reduced activity and reproductive output compared to synchronized bees. Fitness consequences of a three day mismatch were species-specific. Both the early-spring species Osmia cornuta and the mid-spring species Osmia bicornis produced the same number of brood cells after a mismatch of three days as under perfect synchronization. However, O. cornuta decreased the number of female offspring, whereas O. bicornis spread the brood cells over fewer nests, which may increase offspring mortality e.g. due to parasitoids. The late-spring specialist Osmia brevicornis produced fewer brood cells even after a mismatch of three days. Additionally, our results suggest that fitness losses after temporal mismatches are higher during warm than cold springs, as the naturally occurring temperature variability revealed that warm temperatures during starvation decreased the survival rate of O. bicornis.5.We conclude that short temporal mismatches can cause clear fitness losses in solitary bees. Although our results suggest that bees have evolved species-specific strategies to mitigate fitness losses after temporal mismatches, the bees were not able to completely compensate for impacts on their fitness after temporal mismatches with their food resources.This article is protected by copyright. All rights reserved.
      PubDate: 2017-06-22T04:10:42.64356-05:0
      DOI: 10.1111/1365-2656.12694
       
  • Phenological synchrony between a butterfly and its host plants:
           experimental test of effects of spring temperature
    • Authors: Diana Posledovich; Tenna Toftegaard, Christer Wiklund, Johan Ehrlén, Karl Gotthard
      First page: 150
      Abstract: 1.Climate‐driven changes in the relative phenologies of interacting species may potentially alter the outcome of species interactions.2.Phenotypic plasticity is expected to be important for short‐term response to new climate conditions, and differences between species in plasticity are likely to influence their temporal overlap and interaction patterns. As reaction norms of interacting species may be locally adapted, any such climate‐induced change in interaction patterns may vary among localities. However, consequences of spatial variation in plastic responses for species interactions are understudied.3.We experimentally explored how temperature affected synchrony between spring emergence of a butterfly, Anthocharis cardamines, and onset of flowering of five of its host plant species across a latitudinal gradient. We also studied potential effects on synchrony if climate‐driven northward expansions would be faster in the butterflies than in host plants. Lastly, to assess how changes in synchrony influence host use we carried out an experiment to examine the importance of the developmental stage of plant reproductive structures for butterfly oviposition preference.4.In southern locations the butterflies were well‐synchronized with the majority of their local host plant species across temperatures, suggesting that thermal plasticity in butterfly development matches oviposition to host plant development and that thermal reaction norms of insects and plants result in similar advancement of spring phenology in response to warming. In the most northern region, however, relative phenology between the butterfly and two of its host plant species changed with increased temperature. We also show that the developmental stage of plants was important for egg‐laying, and conclude that temperature‐induced changes in synchrony in the northernmost region are likely to lead to shifts in host use in A. cardamines if spring temperatures become warmer. Northern expansion of butterfly populations might possibly have a positive effect on keeping up with host plant phenology with more northern host plant populations.5.Considering that the majority of insect herbivores exploit multiple plant species differing in their phenological response to spring temperatures, temperature‐induced changes in synchrony might lead to shifts in host use and changes in species interactions in many temperate communities.This article is protected by copyright. All rights reserved.
      PubDate: 2017-11-29T06:23:04.619875-05:
      DOI: 10.1111/1365-2656.12770
       
  • Invasive earthworms erode soil biodiversity: A meta-analysis
    • Authors: Olga Ferlian; Nico Eisenhauer, Martin Aguirrebengoa, Mariama Camara, Irene Ramirez-Rojas, Fábio Santos, Krizler Tanalgo, Madhav P. Thakur
      First page: 162
      Abstract: 1.Biological invasions pose a serious threat to biodiversity and ecosystem functioning across ecosystems. Invasions by ecosystem engineers, in particular, have been shown to have dramatic effects in recipient ecosystems. For instance, invasion by earthworms, a belowground invertebrate ecosystem engineer, in previously earthworm-free ecosystems dramatically alters the physico-chemical characteristics of the soil. Studies have shown that such alterations in the soil can have far-reaching impacts on soil organisms, which form a major portion of terrestrial biodiversity.2.Here, we present the first quantitative synthesis of earthworm invasion effects on soil microorganisms and soil invertebrates based on 430 observations from 30 independent studies.3.Our meta-analysis shows a significant decline of the diversity and density of soil invertebrates in response to earthworm invasion with anecic and endogeic earthworms causing the strongest effects. Earthworm invasion effects on soil microorganisms were context-dependent, such as depending on functional group richness of invasive earthworms and soil depth. Microbial biomass and diversity increased in mineral soil layers, with a weak negative effect in organic soil layers, indicating that the mixing of soil layers by earthworms (bioturbation) may homogenize microbial communities across soil layers.4.Our meta-analysis provides a compelling evidence for negative effects of a common invasive belowground ecosystem engineer on belowground biodiversity of recipient ecosystems, which could potentially alter the ecosystem functions and services linked to soil biota.This article is protected by copyright. All rights reserved.
      PubDate: 2017-09-28T05:01:05.219466-05:
      DOI: 10.1111/1365-2656.12746
       
  • Isotopic niche variation from the Holocene to today reveals minimal
           partitioning and individualistic dynamics among four sympatric desert mice
           
    • Authors: Rebecca C. Terry
      First page: 173
      Abstract: 1.Species interact with each other and their environment over a range of temporal scales, yet our understanding of resource partitioning and the mechanisms of species coexistence is largely restricted to modern time‐scales of years to decades. Furthermore, the relative magnitudes of inter‐ versus intraspecific variation in resource use are rarely considered, despite the potential for the latter to influence a species’ ability to cope with changing environmental conditions.2.Modern desert rodent communities are thought to be strongly structured by competitive interactions, with niche partitioning of food resources hypothesized to explain the coexistence of multiple sympatric granivores. Yet the stability of niche dynamics over extended temporal scales within desert rodent communities is unknown.3.I examined the isotopic niche dynamics of four common sympatric desert mice (three granivores: Chaetodipus formosus, Perognathus longimembris, and Reithrodontomys megalotis, and one omnivore: Peromyscus maniculatus) in the Smoke Creek Desert of northwestern Nevada using 13C and 15N isotopes obtained from “Modern” (2008‐2013 CE), “Historical” (1989‐2005 CE), and Holocene fossil specimens spanning the last ca. 7,500 years.4.I found significant variation in niche position, niche breadth, and interspecific niche overlap of these species through time. The niche breadth dynamics of the cricetids (P. maniculatus and R. megalotis) were positively correlated with one another, while the niche breadth dynamics of the heteromyid C. formosus were negatively correlated with those of all other species. Body size, dietary functional group, paleoenvironmental trends, and time‐averaging provided little explanatory power. Importantly, Modern and Historical patterns of resource use and partitioning differed from Holocene baselines in terms of decreased niche overlap and in the absolute and relative position of each species’ niche in at least one isotopic axis.5.These observations suggest that each species’ resource use changed individualistically over the Holocene, hence niche dynamics are poorly explained by the hypothesis of temporally‐stable species interactions at millennial time‐scales. Furthermore, changes to the resource base over the last century (likely due to the spread of invasive cheatgrass) may be increasing resource partitioning in the Modern, pushing species past their baseline ranges of resource use variation.This article is protected by copyright. All rights reserved.
      PubDate: 2017-11-16T07:00:35.991039-05:
      DOI: 10.1111/1365-2656.12771
       
  • Spatio-temporal variation in lifelong telomere dynamics in a long-term
           ecological study
    • Authors: Lewis G. Spurgin; Kat Bebbington, Eleanor A. Fairfield, Martijn Hammers, Jan Komdeur, Terry Burke, Hannah L. Dugdale, David S. Richardson
      First page: 187
      Abstract: Understanding individual-level variation in response to the environment is fundamental to understanding life-history evolution and population dynamics. Telomeres, the protective caps at the ends of chromosomes, shorten in response to oxidative stress, and telomere shortening is correlated with reduced survival and lifespan. Investigating telomere dynamics may help us quantify individual variation in the costs experienced from social and ecological factors, and enhance our understanding of the dynamics of natural populations.Here we study spatio-temporal variation in lifelong telomere dynamics in the Seychelles warbler, Acrocephalus sechellensis. We combine long-term life-history and ecological data with a large longitudinal dataset of mean telomere lengths, consisting of 1808 samples from 22 cohorts born between 1993 and 2014. We provide a detailed analysis of how telomere dynamics vary over individual lifespans and cohorts, and with spatio-temporal variation in the social and ecological environment.We found that telomere length decreases with cross-sectional and longitudinal measures of age, and most rapidly very early in life. However, both cross-sectional and longitudinal data suggested that against this overall pattern of shortening, bouts of telomere length increase occur in some individuals. Using a large number of repeated measurements we show statistically that these increases are unlikely to be explained solely by qPCR measurement error.Telomere length varied markedly among cohorts. Telomere length was positively associated with temporal variation in island-wide insect abundance - a key resource for the insectivorous Seychelles warbler - suggesting that the costs associated with living in harsher environments can be studied by investigating telomere dynamics. We also found evidence for sex-specific relationships between telomeres and tarsus length, potentially reflecting differential costs of growth.Our long-term data show that in a natural population, telomere dynamics vary in a complex manner over individual lifespans, and across space and time. Variance in telomere dynamics among individuals is the product of a wide array of genetic, parental and environmental factors. Explaining this variation more fully will require the integration of comprehensive long-term ecological and genetic data from multiple populations and species. This article is protected by copyright. All rights reserved.
      PubDate: 2017-09-28T05:01:17.712981-05:
      DOI: 10.1111/1365-2656.12741
       
  • Optimising lifetime reproductive output: intermittent breeding as a tactic
           for females in a long‐lived, multiparous mammal
    • Authors: Marine Desprez; Olivier Gimenez, Clive R. McMahon, Mark A. Hindell, Robert G. Harcourt
      First page: 199
      Abstract: 1.In iteroparous species, intermittent breeding is an important life‐history tactic that can greatly affect animal population growth and viability. Despite its importance, few studies have quantified the consequences of breeding pauses on lifetime reproductive output, principally because calculating lifetime reproductive output requires knowledge of each individual's entire reproductive history. This information is extremely difficult to obtain in wild populations.2.We applied novel statistical approaches that account for uncertainty in state assessment and individual heterogeneity to an 18‐year capture‐recapture dataset of 6 631 female southern elephant seals from Macquarie Island. We estimated survival and breeding probabilities, and investigated the consequences of intermittent breeding on lifetime reproductive output.3.We found consistent differences in females’ demographic performance between two heterogeneity classes. In particular, breeding imbued a high cost on survival in the females from the heterogeneity class 2, assumed to be females of lower quality. Individual quality also appeared to play a major role in a female's decision to skip reproduction with females of poorer quality more likely to skip breeding events than females of higher quality.4.Skipping some breeding events allowed females from both heterogeneity classes to increase lifetime reproductive output over females that bred annually. However, females of lower quality produced less offspring over their lifetime.5.Intermittent breeding seems to be used by female southern elephant seals as a tactic to offset reproductive costs on survival and enhance lifetime reproductive output but remains unavoidable and driven by individual‐specific constraints in some other females.This article is protected by copyright. All rights reserved.
      PubDate: 2017-11-23T06:00:29.713953-05:
      DOI: 10.1111/1365-2656.12775
       
  • Interacting effects of unobserved heterogeneity and individual
           stochasticity in the life‐history of the Southern fulmar
    • Authors: Stéphanie Jenouvrier; Lise M. Aubry, Christophe Barbraud, Henri Weimerskirch, Hal Caswell
      First page: 212
      Abstract: 1.Individuals are heterogeneous in many ways. Some of these differences are incorporated as individual states (e.g., age, size, breeding status) in population models. However, substantial amounts of heterogeneity may remain unaccounted for, due to unmeasurable genetic, maternal, or environmental factors.2.Such unobserved heterogeneity (UH) affects the behavior of heterogeneous cohorts via intra‐cohort selection and contributes to inter‐individual variance in demographic outcomes such as longevity and lifetime reproduction. Variance is also produced by individual stochasticity, due to random events in the life cycle of wild organisms, yet no study thus far has attempted to decompose the variance in demographic outcomes into contributions from unobserved heterogeneity and individual stochasticity for an animal population in the wild.3.We developed a stage‐classified matrix population model for the Southern fulmar breeding on Ile des Pétrels, Antarctica. We applied multi‐event, multi‐state markrecapture methods to estimate a finite mixture model accounting for UH in all vital rates and Markov chain methods to calculate demographic outcomes. Finally, we partitioned the variance in demographic outcomes into contributions from unobserved heterogeneity and individual stochasticity.4.We identify three UH groups, differing substantially in longevity, lifetime reproductive output, age at first reproduction, and in the proportion of the life spent in each reproductive state.14% of individuals at fledging have a delayed but high probability of recruitment and extended reproductive lifespan.67% of individuals are less likely to reach adulthood, recruit late and skip breeding often but have the highest adult survival rate.19% of individuals recruit early and attempt to breed often. They are likely to raise their offspring successfully, but experience a relatively short lifespan.Unobserved heterogeneity only explains a small fraction of the variances in longevity (5.9%), age at first reproduction (3.7%) and lifetime reproduction (22%).5.UH can affect the entire life cycle, including survival, development, and reproductive rates, with consequences over the lifetime of individuals and impacts on cohort dynamics. The respective role of unobserved heterogeneity versus individual stochasticity varies greatly among demographic outcomes. We discuss the implication of our finding for the gradient of life‐history strategies observed among species and argue that individual differences should always be accounted for in demographic studies of wild populations.This article is protected by copyright. All rights reserved.
      PubDate: 2017-10-10T09:50:42.471417-05:
      DOI: 10.1111/1365-2656.12752
       
  • Aggression supersedes individual oxygen demand to drive group
           air‐breathing in a social catfish
    • Authors: Shaun S. Killen; Andrew J. Esbaugh, Nicolas F. Martins, F. Tadeu Rantin, David J. McKenzie
      First page: 223
      Abstract: Group‐living is widespread among animals and comes with numerous costs and benefits. To date, research examining group‐living has focused on trade‐offs surrounding foraging, while other forms of resource acquisition have been largely overlooked.Air breathing has evolved in many fish lineages, allowing animals to obtain oxygen in hypoxic aquatic environments. Breathing air increases the threat of predation, so some species perform group air breathing, to reduce individual risk. Within species, air breathing can be influenced by metabolic rate as well as personality, but the mechanisms of group air breathing remain unexplored. It is conceivable that keystone individuals with high metabolic demand or intrinsic tendency to breathe air may drive social breathing, especially in hypoxia.We examined social air breathing in African sharptooth catfish Clarias gariepinus, to determine whether individual physiological traits and spontaneous tendency to breathe air influence the behaviour of entire groups, and whether such influences vary in relation to aquatic oxygen availability.We studied eleven groups of four catfish in a laboratory arena and recorded air‐breathing behaviour, activity, and agonistic interactions at varying levels of hypoxia. Bimodal respirometry was used to estimate individual standard metabolic rate (SMR) and the tendency to utilise aerial oxygen when alone.Fish took more air breaths in groups as compared to when they were alone, regardless of water oxygen content, and displayed temporally clustered air‐breathing behaviour, consistent with existing definitions of synchronous air breathing. However, groups displayed tremendous variability in surfacing behaviour. Aggression by dominant individuals within groups was the main factor influencing air breathing of the entire group. There was no association between individual SMR, or the tendency to obtain oxygen from air when in isolation, and group air breathing.For C. gariepinus, synchronous air breathing is strongly influenced by agonistic interactions, which may expose subordinate individuals to risk of predation. Influential individuals exerted an overriding effect on risk‐taking by the entire group, for reasons independent of their physiological oxygen requirements. Overall, this illustrates that social context can obscure interactions between an individual's physiological and behavioural traits and their tendency to take risks to obtain resources. This article is protected by copyright. All rights reserved.
      PubDate: 2017-10-30T07:12:59.38665-05:0
      DOI: 10.1111/1365-2656.12758
       
  • Critical disease windows shaped by stress exposure alter allocation
           trade‐offs between development and immunity
    • Authors: Lucas J. Kirschman; Erica J. Crespi, Robin W. Warne
      First page: 235
      Abstract: 1.Ubiquitous environmental stressors are often thought to alter animal susceptibility to pathogens and contribute to disease emergence. However, duration of exposure to a stressor is likely critical, because while chronic stress is often immunosuppressive, acute stress can temporarily enhance immune function. Furthermore, host susceptibility to stress and disease often varies with ontogeny; increasing during critical developmental windows. How the duration and timing of exposure to stressors interact to shape critical windows and influence disease processes is not well tested.2.We used ranavirus and larval amphibians as a model system to investigate how physiological stress and pathogenic infection shape development and disease dynamics in vertebrates. Based on a resource allocation model, we designed experiments to test how exposure to stressors may induce resource trade‐offs that shape critical windows and disease processes because the neuroendocrine stress axis coordinates developmental remodeling, immune function, and energy allocation in larval amphibians.3.We used wood frog larvae (Lithobates sylvaticus) to investigate how chronic and acute exposure to corticosterone, the dominant amphibian glucocorticoid hormone, mediates development and immune function via splenocyte immunohistochemistry analysis in association with ranavirus infection.4.Corticosterone treatments affected immune function, as both chronic and acute exposure suppressed splenocyte proliferation, although viral replication rate increased only in the chronic corticosterone treatment.5.Time to metamorphosis and survival depended on both corticosterone treatment and infection status. In the control and chronic corticosterone treatments, ranavirus infection decreased survival and delayed metamorphosis, although chronic corticosterone exposure accelerated time to metamorphosis in uninfected larvae. Acute corticosterone exposure accelerated metamorphosis increased survival in infected larvae.6.Interactions between stress exposure (via glucocorticoid actions) and infection impose resource trade‐offs that shape optimal allocation between development and somatic function. As a result, critical disease windows are likely shaped by stress exposure because any conditions that induce changes in differentiation rates will alter the duration and susceptibility of organisms to stressors or disease.This article is protected by copyright. All rights reserved.
      PubDate: 2017-11-22T09:20:41.645169-05:
      DOI: 10.1111/1365-2656.12778
       
  • Sociodemographic factors modulate the spatial response of brown bears to
           vacancies created by hunting
    • Authors: Shane C. Frank; Martin Leclerc, Fanie Pelletier, Frank Rosell, Jon. E. Swenson, Richard Bischof, Jonas Kindberg, Hans Geir Eiken, Snorre B. Hagen, Andreas Zedrosser
      First page: 247
      Abstract: 1.There is a growing recognition of the importance of indirect effects from hunting on wildlife populations, e.g., social and behavioral changes due to harvest, which occur after the initial offtake. Nonetheless, little is known about how the removal of members of a population influences the spatial configuration of the survivors.2.We studied how surviving brown bears (Ursus arctos) used former home ranges that had belonged to casualties of the annual bear hunting season in southcentral Sweden (2007‐2015). We used resource selection functions to explore the effects of the casualty's and survivor's sex, age, and their pairwise genetic relatedness, population density, and hunting intensity on survivors’ spatial responses to vacated home ranges.3.We tested the competitive release hypothesis, whereby survivors that increase their use of a killed bear's home range are presumed to have been released from intraspecific competition. We found strong support for this hypothesis, as survivors of the same sex as the casualty consistently increased their use of its vacant home range. Patterns were less pronounced or absent when the survivor and casualty were of opposite sex.4.Genetic relatedness between the survivor and the casualty emerged as the most important factor explaining increased use of vacated male home ranges by males, with a stronger response from survivors of lower relatedness. Relatedness was also important for females, but it did not influence use following removal; female survivors used home ranges of higher related female casualties more, both before and after death. Spatial responses by survivors were further influenced by bear age, population density, and hunting intensity.5.We have showed that survivors exhibit a spatial response to vacated home ranges caused by hunting casualties, even in non‐territorial species such as the brown bear. This spatial reorganization can have unintended consequences for population dynamics and interfere with management goals. Altogether, our results underscore the need to better understand the short‐ and long‐term indirect effects of hunting on animal social structure and their resulting distribution in space.This article is protected by copyright. All rights reserved.
      PubDate: 2017-11-13T05:38:53.341762-05:
      DOI: 10.1111/1365-2656.12767
       
  • Divergent migration within lake sturgeon (Acipenser fulvescens)
           populations: multiple distinct patterns exist across an unrestricted
           migration corridor
    • Authors: Steven T. Kessel; Darryl W. Hondorp, Christopher M. Holbrook, James C. Boase, Justin A. Chiotti, Michael V. Thomas, Todd C. Wills, Edward F. Roseman, Richard Drouin, Charles C. Krueger
      First page: 259
      Abstract: 1.Population structure, distribution, abundance, and dispersal arguably underpin the entire field of animal ecology, with consequences for regional species persistence, and provision of ecosystem services. Divergent migration behaviours among individuals or among populations is an important aspect of the ecology of highly‐mobile animals, allowing populations to exploit spatially‐ or temporally‐distributed food and space resources.2.This study investigated the spatial ecology of lake sturgeon (Acipenser fulvescens) within the barrier free Huron‐Erie Corridor (HEC), which connects Lake Huron and Lake Erie of the North American Laurentian Great Lakes.3.Over six years (2011 – 2016), movements of 268 lake sturgeon in the HEC were continuously monitored across the Great Lakes using acoustic telemetry (10 yr battery life acoustic transmitters). Five distinct migration behaviours were identified with hierarchical cluster analysis, based on the phenology and duration of river and lake use.4.Lake sturgeon in the HEC were found to contain a high level of intraspecific divergent migration, including partial migration with the existence of residents. Specific behaviours included year‐round river residency and multiple lake‐migrant behaviours that involved movements between lakes and rivers. Over 85% of individuals were assign to migration behaviours as movements were consistently repeated over the study, which suggested migration behaviours were consistent and persistent in lake sturgeon. Differential use of specific rivers or lakes by acoustic‐tagged lake sturgeon further subdivided individuals into 14 “contingents” (spatiotemporally segregated subgroups).5.Contingents associated with one river (Detroit or St. Clair) were rarely detected in the other river, which confirmed that lake sturgeon in the Detroit and St. Clair represent two semi‐independent populations that could require separate management consideration for their conservation. The distribution of migration behaviours did not vary between populations, sexes, body size, or among release locations, which indicated that intrapopulation variability in migratory behaviour is a general feature of the spatial ecology of lake sturgeon in un‐fragmented landscapes.This article is protected by copyright. All rights reserved.
      PubDate: 2017-12-05T05:10:53.348904-05:
      DOI: 10.1111/1365-2656.12772
       
  • Nowhere to hide: effects of linear features on predator‐prey
           dynamics in a large mammal system
    • Authors: Craig A. DeMars; Stan Boutin
      First page: 274
      Abstract: Rapid landscape alteration associated with human activity is currently challenging the evolved dynamical stability of many predator‐prey systems by forcing species to behaviorally respond to novel environmental stimuli.In many forested systems, linear features (LFs) such as roads, pipelines and resource exploration lines (i.e. seismic lines) are a ubiquitous form of landscape alteration that have been implicated in altering predator‐prey dynamics. One hypothesized effect is that LFs facilitate predator movement into and within prey refugia, thereby increasing predator‐prey spatial overlap.We evaluated this hypothesis in a large mammal system, focusing on the interactions between boreal woodland caribou (Rangifer tarandus caribou) and their two main predators, wolves (Canis lupus) and black bears (Ursus americanus), during the calving season of caribou. In this system, LFs extend into and occur within peatlands (i.e. bogs and nutrient‐poor fens), a habitat type highly used by caribou due to its refugia effects.Using resource selection analyses, we found that LFs increased predator selection of peatlands. Female caribou appeared to respond by avoiding LFs and areas with high LF density. However, in our study area most caribou cannot completely avoid exposure to LFs and variation in female response had demographic effects. In particular, increasing proportional use of LFs by females negatively impacted survival of their neonate calves.Collectively, these results demonstrate how LFs can reduce the efficacy of prey refugia. Mitigating such effects will require limiting or restoring LFs within prey refugia, though the effectiveness of mitigation efforts will depend upon spatial scale, which in turn will be influenced by the life history traits of predator and prey.This article is protected by copyright. All rights reserved.
      PubDate: 2017-10-23T06:15:38.075191-05:
      DOI: 10.1111/1365-2656.12760
       
  • Dietary niche variation and its relationship to lizard population density
    • Authors: Maria Novosolov; Gordon H. Rodda, Alison M. Gainsbury, Shai Meiri
      First page: 285
      Abstract: (1) Insular species are predicted to broaden their niches, in response to having fewer competitors. They can thus exploit a greater proportion of the resource spectrum. In turn, broader niches are hypothesized to facilitate (or be a consequence of) increased population densities.(2) We tested whether insular lizards have broader dietary niches than mainland species, how it relates to competitor and predator richness, and the nature of the relationship between population density and dietary niche breadth.(3) We collected population density and dietary niche breadth data for 36 insular and 59 mainland lizard species, and estimated competitor and predator richness at the localities where diet data were collected. We estimated dietary niche shift by comparing island species to their mainland relatives. We controlled for phylogenetic relatedness, body mass, and the size of the plots over which densities were estimated.(4) We found that island and mainland species had similar niche breadths. Dietary niche breadth was unrelated to competitor and predator richness, on both islands and the mainland. Population density was unrelated to dietary niche breadth across island and mainland populations.(5) Our results indicate that dietary generalism is not an effective way of increasing population density nor is it result of lower competitive pressure. A lower variety of resources on islands may prevent insular animals from increasing their niche breadths even in the face of few competitors.This article is protected by copyright. All rights reserved.
      PubDate: 2017-11-02T06:50:34.49888-05:0
      DOI: 10.1111/1365-2656.12762
       
  • Ants are the major agents of resource removal from tropical rainforests
    • Authors: Hannah M. Griffiths; Louise A. Ashton, Alice E. Walker, Fevziye Hasan, Theodore A. Evans, Paul Eggleton, Catherine L. Parr
      First page: 293
      Abstract: Ants are diverse and abundant, especially in tropical ecosystems. They are often cited as the agents of key ecological processes, but their precise contributions compared with other organisms have rarely been quantified. Through the removal of food resources from the forest floor and subsequent transport to nests, ants play an important role in the redistribution of nutrients in rainforests. This is an essential ecosystem process and a key energetic link between higher trophic levels, decomposers and primary producers.We used the removal of carbohydrate, protein and seed baits as a proxy to quantify the contribution that ants, other invertebrates and vertebrates make to the redistribution of nutrients around the forest floor, and determined to what extent there is functional redundancy across ants, other invertebrate and vertebrate groups.Using a large-scale, field-based manipulation experiment, we suppressed ants from c. 1 ha plots in a lowland tropical rainforest in Sabah, Malaysia. Using a combination of treatment and control plots, and cages to exclude vertebrates, we made food resources available to: (i) the whole foraging community, (ii) only invertebrates and (iii) only non-ant invertebrates. This allowed us to partition bait removal into that taken by vertebrates, non-ant invertebrates and ants. Additionally, we examined how the non-ant invertebrate community responded to ant exclusion.When the whole foraging community had access to food resources, we found that ants were responsible for 52% of total bait removal whilst vertebrates and non-ant invertebrates removed the remaining 48%. Where vertebrates were excluded, ants carried out 61% of invertebrate-mediated bait removal, with all other invertebrates removing the remaining 39%. Vertebrates were responsible for just 24% of bait removal and invertebrates (including ants) collectively removed the remaining 76%. There was no compensation in bait removal rate when ants and vertebrates were excluded, indicating low functional redundancy between these groups.This study is the first to quantify the contribution of ants to the removal of food resources from rainforest floors and thus nutrient redistribution. We demonstrate that ants are functionally unique in this role because no other organisms compensated to maintain bait removal rate in their absence. As such, we strengthen a growing body of evidence establishing ants as ecosystem engineers, and provide new insights into the role of ants in maintaining key ecosystem processes. In this way, we further our basic understanding of the functioning of tropical rainforest ecosystems.In tropical rainforest, ants are ecologically dominant, and are up to 25% of the total animal biomass; however, the contribution of ants compared with other organisms to ecosystem processes has yet to be quantified. The authors show that ants are essential in redistributing nutrients around in ecosystems, and this function cannot be compensated for by other groups.
      PubDate: 2017-08-08T19:01:08.680078-05:
      DOI: 10.1111/1365-2656.12728
       
  • Migratory animals feel the cost of getting sick: a meta‐analysis
           across species
    • Authors: Alice Risely; Marcel Klaassen, Bethany J. Hoye
      First page: 301
      Abstract: 1.Migratory animals are widely assumed to play an important role in the long‐distance dispersal of parasites, and are frequently implicated in the global spread of zoonotic pathogens such as avian influenzas in birds and ebolaviruses in bats. However, infection imposes physiological and behavioural constraints on hosts that may act to curtail parasite dispersal via changes to migratory timing (‘migratory separation’) and survival (‘migratory culling’).2.There remains little consensus regarding the frequency and extent to which migratory separation and migratory culling may operate, despite a growing recognition of the importance of these mechanisms in regulating transmission dynamics in migratory animals.3.We quantitatively reviewed 85 observations extracted from 41 studies to examine how both infection status and infection intensity are related to changes in body stores, refuelling rates, movement capacity, phenology, and survival in migratory hosts across taxa.4.Overall, host infection status was weakly associated with reduced body stores, delayed migration and lower survival, and more strongly associated with reduced movement. Infection intensity was not associated with changes to host body stores, but was associated with moderate negative effects on movement, phenology and survival.5.In conclusion, we found evidence for negative effects of infection on host phenology and survival, but the effects were relatively small. This may have implications for the extent to which migratory separation and migratory culling act to limit parasite dispersal in migratory systems. We propose a number of recommendations for future research that will further advance our understanding of how migratory separation and migratory culling may shape host‐parasite dynamics along migratory routes globally.This article is protected by copyright. All rights reserved.
      PubDate: 2017-11-20T06:50:57.514901-05:
      DOI: 10.1111/1365-2656.12766
       
  • Genetic Allee effects and their interaction with ecological Allee effects
    • Abstract: 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.In this study, we aim to (i) develop a meaningful notion of a ‘strong genetic Allee effect’, (ii) explore whether and under what conditions such an effect can arise from inbreeding depression due to recessive deleterious mutations, and (iii) quantify the interaction of potential genetic Allee effects with the well‐known mate‐finding Allee effect.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 analyse simple stochastic models for the ecology and genetics of small populations.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.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.The modeling results indicate that inbreeding depression can produce a strong Allee effect where populations below a certain critical size tend to go extinct. Such genetic Allee effects can interact with ecological Allee effects, for example those due to mate‐finding difficulties, to increase the extinction risk of small populations.
       
 
 
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