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  Subjects -> BIOLOGY (Total: 3003 journals)
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ZOOLOGY (133 journals)                     

Showing 1 - 133 of 133 Journals sorted alphabetically
Acta Herpetologica     Open Access   (Followers: 7)
Acta Theriologica     Full-text available via subscription   (Followers: 6)
Acta Zoologica     Hybrid Journal   (Followers: 6)
Acta Zoologica Cracoviensia     Free   (Followers: 2)
Acta zoológica mexicana     Open Access  
Advances in Zoology and Botany     Open Access  
African Journal of Herpetology     Full-text available via subscription   (Followers: 6)
African Journal of Wildlife Research     Full-text available via subscription   (Followers: 3)
African Zoology     Hybrid Journal   (Followers: 6)
American Journal of Zoological Research     Open Access   (Followers: 1)
Animal Behaviour     Hybrid Journal   (Followers: 163)
Animal Biology     Hybrid Journal   (Followers: 8)
Animal Biology & Animal Husbandry     Open Access   (Followers: 4)
Animal Biotelemetry     Open Access   (Followers: 1)
Animal Genetics     Hybrid Journal   (Followers: 8)
Animal Migration     Open Access   (Followers: 1)
Animal Studies Journal     Open Access   (Followers: 7)
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: 7)
Applied Animal Behaviour Science     Hybrid Journal   (Followers: 17)
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: 9)
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: 25)
Brazilian Journal of Veterinary Research and Animal Science     Open Access   (Followers: 7)
British Birds     Full-text available via subscription   (Followers: 26)
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: 14)
Canadian Zooarchaeology / Zooarchéologie canadienne     Open Access   (Followers: 2)
Contributions to Zoology     Open Access   (Followers: 3)
Current Zoology     Full-text available via subscription  
Der Zoologische Garten     Full-text available via subscription   (Followers: 2)
Ecology of Freshwater Fish     Hybrid Journal   (Followers: 18)
European Journal of Taxonomy     Open Access   (Followers: 4)
Euscorpius     Open Access  
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: 5)
Hystrix, the Italian Journal of Mammalogy     Open Access  
i-Perception     Open Access   (Followers: 3)
Iheringia. Série Zoologia     Open Access   (Followers: 1)
In Vitro Cellular & Developmental Biology - Animal     Hybrid Journal   (Followers: 1)
Integrative Zoology     Hybrid Journal  
International Journal of Odonatology     Hybrid Journal   (Followers: 1)
International Journal of Zoological Research     Open Access   (Followers: 1)
International Journal of Zoology     Open Access   (Followers: 1)
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: 63)
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: 15)
Journal of Morphology     Hybrid Journal   (Followers: 5)
Journal of Threatened Taxa     Open Access  
Journal of Venomous Animals and Toxins     Open Access   (Followers: 3)
Journal of Venomous Animals and Toxins including Tropical Diseases     Open Access  
Journal of Wildlife Management     Hybrid Journal   (Followers: 37)
Journal of Zoological Systematics and Evolutionary Research     Hybrid Journal   (Followers: 4)
Journal of Zoology     Hybrid Journal   (Followers: 22)
Laboratory Animals     Hybrid Journal   (Followers: 14)
Mammalia     Hybrid Journal   (Followers: 5)
Mastozoología Neotropical     Open Access  
Memorias de la Conferencia Interna en Medicina y Aprovechamiento de Fauna Silvestre, Exótica y no Convencional     Open Access  
Monographs of the Transvaal Museum     Full-text available via subscription  
Natural History Sciences     Hybrid Journal   (Followers: 2)
New Zealand Journal of Zoology     Hybrid Journal   (Followers: 8)
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: 19)
Research in Zoology     Open Access   (Followers: 2)
Revista Brasileira de Reprodução Animal     Open Access  
Revista Brasileira de Zoologia     Open Access  
Revista de Biología Marina y Oceanografía     Open Access  
Revista de Educação Continuada em Medicina Veterinária e Zootecnia     Open Access  
Revista de Zoologia     Open Access   (Followers: 1)
Russian Journal of Herpetology     Full-text available via subscription   (Followers: 3)
Scientific Journal of Animal Science     Open Access   (Followers: 5)
Scientific Journal of Zoology     Open Access   (Followers: 4)
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: 5)
Sri Lanka Journal of Aquatic Sciences     Open Access   (Followers: 1)
Travaux du Muséum National d’Histoire Naturelle “Grigore Antipa”     Open Access  
Tropical Zoology     Partially Free   (Followers: 2)
University Journal of Zoology, Rajshahi University     Open Access  
Veterinária e Zootecnia     Open Access  
Waterbirds     Full-text available via subscription   (Followers: 10)
Wildlife Society Bulletin     Hybrid Journal   (Followers: 8)
World Rabbit Science     Open Access  
Zoo Biology     Hybrid Journal   (Followers: 10)
ZooKeys     Open Access   (Followers: 5)
Zoologia (Curitiba)     Open Access   (Followers: 1)
Zoologica Poloniae : The Journal of Polish Zoological Society     Open Access   (Followers: 1)
Zoologica Scripta     Hybrid Journal   (Followers: 4)
Zoological Journal of the Linnean Society     Hybrid Journal   (Followers: 13)
Zoological Letters     Open Access  
Zoological Science     Full-text available via subscription   (Followers: 2)
Zoological Studies     Open Access   (Followers: 1)
Zoologische Mededelingen     Open Access   (Followers: 1)
Zoologischer Anzeiger - A Journal of Comparative Zoology     Hybrid Journal   (Followers: 1)
Zoologist (The)     Full-text available via subscription  
Zoology     Hybrid Journal   (Followers: 5)
Zoology and Ecology     Hybrid Journal   (Followers: 4)
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]   [63 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  [1579 journals]
  • 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
       
  • An evolutionary framework outlining the integration of individual social
           and spatial ecology
    • 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.
       
  • Divergent migration within lake sturgeon (Acipenser fulvescens)
           populations: multiple distinct patterns exist across an unrestricted
           migration corridor
    • 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.
       
  • Isotopic niche variation from the Holocene to today reveals minimal
           partitioning and individualistic dynamics among four sympatric desert mice
           
    • 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.
       
  • Phenological synchrony between a butterfly and its host plants:
           experimental test of effects of spring temperature
    • 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.
       
  • Dawn song in natural and artificial continuous day: Light pollution
           affects songbirds at high latitudes
    • Abstract: In Focus: Da Silva, A., & Kempenaers, B. (2017). Singing from North to South: Latitudinal variation in timing of dawn singing under natural and artificial light conditions. Journal of Animal Ecology, 86, 1286–1297. doi: 10.1111/1365-2656.12739Satellite images of the world at night show bright dots connected by glowing lines crisscrossing the globe. As these connect‐the‐dots become brighter and expand into more and more remote regions, much of the flora and fauna of the world are experiencing evolutionarily unprecedented levels of light at night. Light cues are essential to most physiological and behavioural processes, and so the need to measure the effects of light pollution on these processes is critical. In this issue, Da Silva and Kempenaers take on this task using an important reproductive behaviour in songbirds—dawn song. The geographic, temporal and taxonomic breadth of sampling in this study allows for a close examination of a potentially complex interaction between light pollution and natural variation in the behaviour of dawn singing across latitude, season and species. Their extensive dataset highlights complexity in how songbirds respond to light pollution. Although light pollution has a strong effect on the timing of dawn song, not all songbirds respond the same way to light pollution, and the effects of light pollution vary with changes in natural light levels. Early dawn singers show more flexibility in the timing of dawn song across the season and across latitudes than late dawn singers, and also appear less affected by light pollution at high latitudes than are late dawn singers. These findings suggest that not all songbirds are responding to artificial continuous daylight as they do to natural continuous daylight, highlighting the general need to measure the fitness effects of light pollution.Early dawn singers show more flexibility in timing of dawn song across latitudes and also appear less affected by light pollution at high latitudes than are late dawn singers. These findings suggest not all songbirds respond to artificial continuous daylight as they do to natural continuous daylight.
       
  • Do host‐associated gut microbiota mediate the effect of an herbicide on
           disease risk in frogs'
    • 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.
       
  • Host effects on microbiota community assembly
    • 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.
       
  • Using host species traits to understand the consequences of resource
           provisioning for host–parasite interactions
    • 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.
       
  • Sociodemographic factors modulate the spatial response of brown bears to
           vacancies created by hunting
    • 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.
       
  • Migratory animals feel the cost of getting sick: a meta‐analysis
           across species
    • 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.
       
  • When to choose dynamic versus static social network analysis
    • 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.
       
  • Resistance and tolerance: the role of nutrients on pathogen dynamics and
           infection outcomes in an insect host
    • 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.
       
  • REVIEW: Dynamic, spatial models of parasite transmission in wildlife:
           their structure, applications, and remaining challenges
    • 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.
       
  • Dietary niche variation and its relationship to lizard population density
    • 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.
       
  • Nowhere to hide: effects of linear features on predator‐prey
           dynamics in a large mammal system
    • 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.
       
  • Allee Effects in Social Species
    • 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.
       
  • Aggression supersedes individual oxygen demand to drive group
           air‐breathing in a social catfish
    • 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.
       
  • Fast growing oysters show reduced capacity to provide a thermal refuge to
           intertidal biodiversity at high temperatures
    • Abstract: 1.Ecosystem engineers that modify the thermal environment experienced by associated organisms might assist in the climate change adaptation of species. This depends upon the ability of ecosystem engineers to persist and continue to ameliorate thermal stress under changing climatic conditions – traits that may display significant intraspecific variation.2.In the physically stressful intertidal, the complex three‐dimensional structure of oysters provides shading and traps moisture during aerial exposure at low tide. We assessed variation in the capacity of a faster‐ and slower‐growing population of the Sydney Rock Oyster, Saccostrea glomerata, to persist, form three‐dimensional structure and provide a cool microhabitat to invertebrates under warmer conditions.3.The two populations of oysters were exposed to a temperature gradient in the field by attaching them to passively warmed white, grey and black stone pavers and their growth, survivorship and colonisation by invertebrates was monitored over a 12 month period.4.Oysters displayed a trade‐off between fast growth and thermal tolerance. The growth advantage of the fast‐growing population diminished with increasing substrate temperature and at higher temperatures the faster‐growing oysters suffered greater mortality, formed less habitat, and were consequently less effective at ameliorating low‐tide air temperature extremes than slower‐growing oysters. The greater survivorship of slower‐growing oysters, in turn, produced a cooler microclimate which fed back to further bolster oyster survivorship. Invertebrate recruitment increased with habitat cover, and was greater among the slower than the faster‐growing population.5.Our results show that the capacity of ecosystem engineers to serve as microhabitat refugia to associated organisms in a warming climate displays marked intraspecific variation. Our study also adds to growing evidence that fast growth may come at the expense of thermal tolerance.This article is protected by copyright. All rights reserved.
       
  • A cascade of destabilizations: combining Wolbachia and Allee effects to
           eradicate insect pests
    • 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.
       
  • Toward a geography of omnivory: Omnivores increase carnivory when sodium
           is limiting
    • Abstract: Toward understanding the geography of omnivory, we tested three hypotheses that predict the proportion of animal tissue consumed: The Sodium Limitation Hypothesis predicts that omnivores increase animal consumption in Na‐poor environments because Na bioaccumulates from plants to predators; thus, heterotrophs are Na‐rich sources. The Nitrogen Limitation and Habitat Productivity Hypotheses use the same logic to predict more animal consumption in N‐poor and productive environments respectively.Omnivory is a common trophic strategy, but what determines the balance of plant and animal tissue omnivores consume is relatively unexplored. Most of what we know comes from single populations at local scales. Here we quantitatively test these three hypotheses at a large geographic scale and across 20 species of omnivorous ants.We tested each hypothesis using N stable isotopes (δ15N) to quantify the degree of carnivory in ant populations in 20 forests that span 12° latitude from Georgia to Maine, USA. We used the difference in δ15N between 20 ant conspecifics in 10 genera between two paired forests (10 pairs of 20 forests) that consisted of a coastal and inland forests on the same latitude to determine if the proportion of animal tissue consumed could be predicted based on Na, N or NPP.Sodium gradients accounted for 18% of the variation in δ15N, 45% if one outlier ant species was omitted. In contrast, the Nitrogen Limitation and Habitat Productivity Hypotheses, which predict more animal consumption in N‐poor and more productive environments respectively, failed to vary with δ15N.Our results reveal a geography of omnivory driven in part by access to Na.This article is protected by copyright. All rights reserved.
       
  • Novel insights on population and range edge dynamics using an unparalleled
           spatiotemporal record of species invasion
    • 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.
       
  • Interacting effects of unobserved heterogeneity and individual
           stochasticity in the life‐history of the Southern fulmar
    • 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.
       
  • An experimental test of the physiological consequences of avian malaria
           infection
    • Abstract: 1.Chronic, low‐intensity parasite infections can reduce host fitness through negative impacts on reproduction and survival, even if they produce few overt symptoms. As a result, these parasites can influence the evolution of host morphology, behavior, and physiology. The physiological consequences of chronic infection can provide insight into the processes underlying parasite‐driven natural selection.2.Here, we evaluate the physiological consequences of natural, low‐intensity infection in an avian host‐parasite system: adult male red‐winged blackbirds (Agelaius phoeniceus) infected with haemosporidian parasites. Chronic haemosporidian infection has previously been shown to reduce both reproductive success and survival in several avian species.3.We used anti‐malarial medications to experimentally reduce haemosporidian parasitemia (the proportion of blood cells infected with haemosporidian parasites) and measured the effect of treatment on body condition, hematology, immune function, physiological stress, and oxidative state.4.Treatment with an anti‐malarial medication reduced parasitemia for the most prevalent haemosporidian parasites from the genus Plasmodium. Treatment also increased hemoglobin and hematocrit, and decreased red blood cell production rates. We detected no effect of treatment on body condition, immune metrics, plasma corticosterone concentrations, total antioxidant capacity, or reactive oxygen metabolites.5.Our results suggest that the damage and replacement of red blood cells during infection could be important costs of chronic haemosporidian infection. Strong links between parasitemia and the physiological consequences of infection indicate that even for relatively low intensity infections, measuring parasitemia rather than only presence/absence could be important when evaluating the role of infection in influencing hosts’ behavior, physiology, or fitness.This article is protected by copyright. All rights reserved.
       
  • Linking social and spatial networks to viral community phylogenetics
           reveal subtype specific transmission dynamics in African lions
    • Abstract: 1.Heterogeneity within pathogen species can have important consequences for how pathogens transmit across landscapes; however, discerning different transmission routes is challenging.2.Here we apply both phylodynamic and phylogenetic community ecology techniques to examine the consequences of pathogen heterogeneity on transmission by assessing subtype specific transmission pathways in a social carnivore.3.We use comprehensive social and spatial network data to examine transmission pathways for three subtypes of feline immunodeficiency virus (FIVPle) in African lions (Panthera leo) at multiple scales in the Serengeti National Park, Tanzania. We used FIVPle molecular data to examine the role of social organization and lion density in shaping transmission pathways and tested to what extent vertical (i.e., father and/or mother offspring relationships) or horizontal (between unrelated individuals) transmission underpinned these patterns for each subtype. Using the same data, we constructed subtype specific FIVPle co‐occurrence networks and assessed what combination of social networks, spatial networks, or co‐infection best structured the FIVPle network.4.While social organization (i.e., pride) was an important component of FIVPle transmission pathways at all scales, we find that FIVPle subtypes exhibited different transmission pathways at within‐ and between‐pride scales. A combination of social and spatial networks, coupled with consideration of subtype co‐infection, was likely to be important for FIVPle transmission for the two major subtypes, but the relative contribution of each factor was strongly subtype specific.5.Our study provides evidence that pathogen heterogeneity is important in understanding pathogen transmission, which could have consequences for how endemic pathogens are managed. Furthermore, we demonstrate that community phylogenetic ecology coupled with phylodynamic techniques can reveal insights into the differential evolutionary pressures acting on virus subtypes, which can manifest into landscape‐level effects.This article is protected by copyright. All rights reserved.
       
  • Non-random dispersal mediates invader impacts on the invertebrate
           community
    • Abstract: (1) Dispersers are often not a random draw from a population, dispersal propensity being conditional on individual phenotypic traits and local conditions. This non-randomness consequently results in phenotypic differences between dispersers and non-dispersers and, in the context of biological invasions, in an invasion front made of individuals with a biased phenotype. This bias of phenotypes at the front may subsequently modulate the strength of ecological effects of an invasive species on invaded communities.(2) We recently demonstrated that more asocial mosquitofish (Gambusia affinis), one of the 100 worst invasive species, disperse further, suggesting a sociability-biased invasion front. As behavioural types are related to the strength of interspecific interactions, an invasion by a biased subset of individuals should have important ecological implications for native communities.(3) Here, we tested the impact of phenotypic biases in dispersing individuals (relative to non-dispersers) on prey communities in experimental mesocosms.(4) We show that dispersers reduce prey abundance more than do non-dispersers during the first 4 weeks after introduction, and that the disperser's social types are likely drivers of these differences. These differences in prey communities disappeared after 8 weeks suggesting prey community resilience against predation in these mesocosm ecosystems.(5) Consequently, we call for the integration of non-random dispersal, dispersal syndromes and more generally intraspecific variation into studies predicting the impacts of invasions.This article is protected by copyright. All rights reserved.
       
  • Leaf odour cues enable non-random foraging by mammalian herbivores
    • Abstract: Searching for food is the first critical stage of foraging, and search efficiency is enhanced when foragers use cues from foods they seek. Yet we know little about food cues used by one major group of mammals, the herbivores, a highly-interactive component of most ecosystems. How herbivores forage and what disrupts this process both have significant ecological and evolutionary consequences beyond the animals themselves.Our aim was to investigate how free-ranging mammalian herbivores exploit leaf odour cues to find food plants amongst a natural and complex vegetation community. Our study system comprised the native “deer equivalent” of eastern Australian forests, the swamp wallaby Wallabia bicolor, and seedlings of Eucalyptus, the foundation tree genus in these ecosystems. We quantified how foraging wallabies responded to odour cues from plants manipulated in several ways: varying the quantity of visually concealed leaves, comparing damaged vs. undamaged leaves, and whole plants vs. those with suppressed cues.The rate of discovery of leaves by wallabies increased with odour cue magnitude, yet animals were extremely sensitive to even a tiny odour source of just a few leaves. Whole seedlings were discovered faster if their leaves were damaged. Wallabies found whole seedlings and those with suppressed visual cues equally rapidly, day and night. Seedlings with very little odour were discovered mainly by day, as nocturnal foraging success was severely disrupted.This study shows how leaf odour attracts mammalian herbivores to food plants, enabling non-random search for even tiny odour sources. As damaged leaves enhanced discovery, we suggest that the benefit of attracting natural enemies to invertebrate herbivores feeding on plants (potential “cry for help”) may be offset by a cost — increased browsing by mammalian herbivores. This cost should be incorporated into multi-trophic plant-animal studies. Finally, the breakdown in capacity to find plants at night suggests substantial but unrecognised foraging costs to herbivores when abiotic factors, such as cold temperatures or pollution, reduce or degrade plant odour cues. We predict that an increasingly polluted world will alter the foraging success of mammalian herbivores, with significant ecological ramifications given that browsing can shape ecosystems.This article is protected by copyright. All rights reserved.
       
  • Why are some plant-pollinator networks more nested than others'
    • Abstract: Empirical studies have found that the mutualistic interactions forming the structure of plant-pollinator networks are typically more nested than expected by chance alone. Additionally, theoretical studies have shown a positive association between the nested structure of mutualistic networks and community persistence. Yet, it has been shown that some plant-pollinator networks may be more nested than others, raising the interesting question of which factors are responsible for such enhanced nested structure.It has been argued that ordered network structures may increase the persistence of ecological communities under less predictable environments. This suggests that nested structures of plant-pollinator networks could be more advantageous under highly seasonal environments. While several studies have investigated the link between nestedness and various environmental variables, unfortunately, there has been no unified answer to validate these predictions. Here, we move from the problem of describing network structures to the problem of comparing network structures. We develop comparative statistics, and apply them to investigate the association between the nested structure of 59 plant-pollinator networks and the temperature seasonality present in their locations.We demonstrate that higher levels of nestedness are associated with a higher temperature seasonality. We show that the previous lack of agreement came from an extended practice of using standardized measures of nestedness that cannot be compared across different networks.Importantly, our observations complement theory showing that more nested network structures can increase the range of environmental conditions compatible with species coexistence in mutualistic systems, also known as structural stability. This increase in nestedness should be more advantageous and occur more often in locations subject to random environmental perturbations, which could be driven by highly changing or seasonal environments. This synthesis of theory and observations could prove relevant for a better understanding of the ecological processes driving the assembly and persistence of ecological communities.This article is protected by copyright. All rights reserved.
       
  • Foraging traits modulate stingless bee community disassembly under forest
           loss
    • Abstract: 1. Anthropogenic land use change is an important driver of impacts to biological communities and the ecosystem services they provide. Pollination is one ecosystem service that may be threatened by community disassembly. Relatively little is known about changes in bee community composition in the tropics, where pollination limitation is most severe and land use change is rapid. Understanding how anthropogenic changes alter community composition and functioning has been hampered by high variability in responses of individual species. Trait-based approaches, however, are emerging as a potential method for understanding responses of ecologically-similar species to global change.2. We studied how communities of tropical, eusocial stingless bees (Apidae: Meliponini) disassemble when forest is lost. These bees are vital tropical pollinators that exhibit high trait diversity, but are under considerable threat from human activities.3. We compared functional traits of stingless bee species found in pastures surrounded by differing amounts forest in an extensively deforested landscape in southern Costa Rica.4. Our results suggest that foraging traits modulate competitive interactions that underlie community disassembly patterns. In contrast to both theoretical predictions and temperate bee communities, we found that stingless bee species with the widest diet breadths were less likely to persist in sites with less forest. These wide-diet-breadth species also tend to be solitary foragers, and are competitively subordinate to group-foraging stingless bee species. Thus, displacement by dominant, group-foraging species may make subordinate species more dependent on the larger or more diversified resource pool that natural habitats offer. We also found that traits that may reduce reliance on trees – nesting in the ground or inside nests of other species – correlated with persistence in highly deforested landscapes.5. The functional trait perspective we employed enabled capturing community processes in analyses and suggests that land use change may disassemble bee communities via different mechanisms in temperate and tropical areas. Our results further suggest that community processes, such as competition, can be important regulators of community disassembly under land use change. A better understanding of community disassembly processes is critical for conserving and restoring pollinator communities and the ecosystem services and functions they provide.This article is protected by copyright. All rights reserved.
       
  • Life stage and species identity affect whether habitat subsidies enhance
           or simply redistribute consumer biomass
    • Abstract: 1.Quantifying the response of mobile consumers to changes in habitat availability is essential for determining the degree to which population-level productivity is habitat limited rather than regulated by other, potentially density-independent factors.2.Over landscape scales, this can be explored by monitoring changes in density and foraging as habitat availability varies. As habitat availability increases, densities may: (1) decrease (unit-area production decreases; weak habitat limitation); (2) remain stable (unit-area production remains stable; habitat limitation); or (3) increase (unit-area production increases; strong habitat limitation).3.We tested the response of mobile estuarine consumers over five months to changes in habitat availability in situ by comparing densities and feeding rates on artificial reefs that were or were not adjacent to neighboring artificial reefs or nearby natural reefs).4.Using either constructed or natural reefs to manipulate habitat availability, we documented three-fold density decreases among juvenile stone crabs as habitat increased (i.e. weak habitat imitation). However, for adult stone crabs, density remained stable across treatments, demonstrating that habitat limitation presents a bottleneck in this species’ later life history. Oyster toadfish densities also did not change with increasing habitat availability (i.e. habitat limitation), but densities of other cryptic fishes decreased as habitat availability increased (i.e. weak limitation). Feeding and abundance data suggested that some mobile fishes experience habitat limitation, or, potentially in one case, strong limitation across our habitat manipulations.5.These findings of significant, community-level habitat limitation provide insight into how global declines in structurally complex estuarine habitats may have reduced the fishery production of coastal ecosystems.This article is protected by copyright. All rights reserved.
       
  • Invasive earthworms erode soil biodiversity: A meta-analysis
    • 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.
       
  • Wildlife disease ecology from the individual to the population: insights
           
    • 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.
       
  • Mammal-induced trophic cascades in invertebrate food webs are modulated by
           grazing intensity in subalpine grassland
    • Abstract: 1. Even though mammalian herbivores can exert strong indirect effects on other animals by altering the vegetation, the study of trophic cascades retains a focus on apex predators and their top-down forces. Bottom-up trophic interaction chains induced by mammalian herbivores, particularly in invertebrate food webs, remain largely unexplored.2. We tested whether effects of mammalian herbivores on the vegetation ricochet back up several trophic levels of the invertebrate food web. We further tested two alternative hypotheses: the strength of herbivore-induced indirect interactions either increases with plant productivity because of a concurrent higher grazing intensity, or it decreases because of a higher plant tolerance to grazing.3. We progressively excluded large, medium, and small herbivorous mammals from replicated plots of 6 m2 in productive, intensively grazed short-grass vegetation and less productive, less intensively grazed tall-grass vegetation of subalpine grasslands. We measured vegetation quantity, quality, structure, and composition, and determined the abundance of invertebrate herbivores, detritivores, omnivores, and predators. We used Structural Equation Modelling to test vegetation-mediated cascading effects of the different mammalian herbivores across different trophic groups of invertebrates.4. In the short-grass vegetation, mammals caused changes in vegetation quantity and thickness. These changes directly affected detritivorous and predatory invertebrate abundance, yet indirectly affected predatory and omnivorous invertebrates through a bottom-up trophic cascade via changes in herbivorous invertebrate abundance. In the tall-grass vegetation, mammal-induced changes in vegetation quality and composition affected detritivorous invertebrates and in turn omnivorous invertebrates, but these cascading effects were weaker than those in the short-grass vegetation. Smaller mammals were at least as important as large mammals in structuring the invertebrate food web.5. Our results demonstrate that differently sized mammalian herbivores can trigger trophic cascades in the local invertebrate food web. Our findings further support the hypothesis that herbivore-induced indirect interactions are stronger in more productive systems because of higher foraging intensity, as opposed to the hypothesis that a higher grazing tolerance of plants should dampen herbivore-induced indirect interactions in productive systems.This article is protected by copyright. All rights reserved.
       
  • Sexual selection on male body size, genital length and heterozygosity:
           consistency across habitats and social settings
    • Abstract: 1. Spatial and temporal variation in environmental factors and the social setting can help to maintain genetic variation in sexually selected traits if it affects the strength of directional selection. A key social parameter which affects the intensity of, and sometimes predicts the response to, mating competition is the operational sex ratio (OSR; ratio of receptive males to females).2. How the OSR affects selection for specific male traits is poorly understood. It is also unclear how sexual selection is affected by interactions between the OSR and environmental factors, such as habitat complexity, that alter key male-female interactions such as mate encounter rates.3. Here, we experimentally manipulated the OSR and habitat complexity and quantified sexual selection on male mosquitofish (Gambusia holbrooki) by directly measuring male reproductive success (i.e. paternity).4. We show that, despite a more equitable sharing of paternity (i.e. higher levels of multiple paternity) under a male-biased OSR, selection on focal male traits was unaffected by the OSR or habitat complexity. Instead, sexual selection consistently, and significantly, favoured smaller bodied males, males with higher genome wide heterozygosity (based on >3000 SNP markers), and males with a relatively long gonopodium (intromittent organ).5. Our results show that sexual selection on male body size, relative genital size and heterozygosity in this system is consistent across environments that vary in ecological parameters that are expected to influence mate encounter rates.This article is protected by copyright. All rights reserved.
       
  • Singing from North to South: latitudinal variation in timing of dawn
           singing under natural and artificial light conditions
    • Abstract: 1. Animals breeding at northern latitudes experience drastic changes in daily light conditions during the breeding season with decreasing periods of darkness, whereas those living at lower latitudes are exposed to naturally dark nights throughout the year. Nowadays, many animals are also exposed to artificial night lighting (often referred to as light pollution).2. Animals strongly rely on variation in light levels to time their daily and seasonal behaviour. Previous work on passerine birds showed that artificial night lighting leads to earlier onset of dawn song. However, these studies were carried out at intermediate latitudes with more limited seasonal changes in daylength, and we still lack an understanding of the impact of artificial night lighting in relation to variation in natural light conditions.3. We investigated the influence of natural and artificial light conditions on the timing of dawn singing in five common songbird species in each of three regions in Europe that differed in natural variation in daylength (northern Finland, 65°N; southern Germany, 48°N; southern Spain, 37°N). In each region, we selected five peri-urban forest sites with and five without street lighting, and recorded dawn singing at the beginning of the local breeding season.4. Our results show that the earliest natural singers, i.e., European robins (Erithacus rubecula) and common blackbirds (Turdus merula), started dawn singing earlier along with the natural increase in night brightness in Finland, with no additional effects of artificial night lighting. In contrast, the later singers, i.e., great tits (Parus major), blue tits (Cyanistes caeruleus), and chaffinches (Fringilla coelebs), showed similar onsets of dawn song relative to sunrise across the season and similar effects of artificial night lighting at all latitudes.5. Artificial night lighting affected great tits, blue tits and chaffinches even in northern Finland where nights became very bright. Proximate factors such as differential light sensitivities may explain why early singers showed more plastic behavioural responses to naturally and artificially bright nights. The maintenance of rhythmicity in the late singers during bright northern nights and under artificial night lighting may also be an adaptive response to predation risk or costs of sleep loss.This article is protected by copyright. All rights reserved.
       
  • Spatio-temporal variation in lifelong telomere dynamics in a long-term
           ecological study
    • 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.
       
  • Temperature drives abundance fluctuations, but spatial dynamics is
           constrained by landscape configuration: implications for climate-driven
           range shift in a butterfly
    • Abstract: Prediction of species distributions in an altered climate requires knowledge on how global- and local-scale factors interact to limit their current distributions. Such knowledge can be gained through studies of spatial population dynamics at climatic range margins.Here, using a butterfly (Pyrgus armoricanus) as model species, we first predicted based on species distribution modelling that its climatically suitable habitats currently extend north of its realized range. Projecting the model into scenarios of future climate, we showed that the distribution of climatically suitable habitats may shift northward by an additional 400 km in the future.Second, we used a 13-year monitoring data set including the majority of all habitat patches at the species’ northern range margin to assess the synergetic impact of temperature fluctuations and spatial distribution of habitat, microclimatic conditions and habitat quality, on abundance and colonisation-extinction dynamics.The fluctuation in abundance between years was almost entirely determined by the variation in temperature during the species’ larval development. In contrast, colonisation and extinction dynamics were better explained by patch area, between-patch connectivity, and host plant density. This suggests that the response of the species to future climate change may be limited by future land-use and how its host plants respond to climate change. It is thus probable that dispersal limitation will prevent P. armoricanus from reaching its potential future distribution.We argue that models of range dynamics should consider the factors influencing metapopulation dynamics, especially at the range edges, and not only broad-scale climate. It includes factors acting at the scale of habitat patches such as habitat quality and microclimate, and landscape-scale factors such as the spatial configuration of potentially suitable patches. Knowledge of population dynamics under various environmental conditions, and the incorporation of realistic scenarios of future land-use, appear thus essential to provide predictions useful for actions mitigating the negative effects of climate change.This article is protected by copyright. All rights reserved.
       
  • Physiology at near-critical temperatures, but not critical limits, varies
           between two lizard species that partition the thermal environment
    • Abstract: The mechanisms that mediate the interaction between the thermal environment and species’ ranges are generally uncertain. Thermal environments may directly restrict species when environments exceed tolerance limits (i.e. the fundamental niche). However, thermal environments might also differentially affect relative performance among species prior to fundamental tolerances being met (i.e. the realized niche).We examined stress physiology (plasma glucose and corticosterone), mitochondrial performance, and the muscle metabolome of congeneric lizards that naturally partition the thermal niche, Elgaria multicarinata (southern alligator lizards; SAL) and E. coerulea (northern alligator lizards; NAL), in response to a thermal challenge to quantify variation in physiological performance and tolerance.Both NAL and SAL displayed physiological stress in response to high temperature, but neither showed signs of irreversible damage. NAL displayed a higher baseline mitochondrial respiration rate than SAL. Moreover, NAL substantially adjusted their physiology in response to thermal challenge whereas SAL did not. For example, the metabolite profile of NAL shifted with changes in key energetic molecules, whereas these were unaffected in SAL.Our results indicate that near-critical high temperatures should incur greater energetic cost in NAL than SAL via an elevated metabolic rate and changes to the metabolome. Thus, SAL displace NAL in warm environments that are within NAL's fundamental thermal niche, but relatively costly.Our results suggest that sub-critical thermal events can contribute to biogeographic patterns via physiological differences that alter the relative costs of living in warm or cool environments.This article is protected by copyright. All rights reserved.
       
  • Parasite metacommunities: Evaluating the roles of host community
           composition and environmental gradients in structuring symbiont
           communities within amphibians
    • 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.
       
  • Ants are the major agents of resource removal from tropical rainforests
    • 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.
       
  • Territory Size Decreases Minimally with Increasing Food Abundance in
           Stream Salmonids: Implications for Population Regulation
    • Abstract: How the local density of territorial animals responds to changes in food abundance will depend on the flexibility of territory size. Quantitative estimates of territory size over a broad range of food abundance are relatively rare because of the difficulty of measuring food abundance in the wild.Stream salmonids are an ideal model system for investigating flexibility in territory size, because food abundance can be quantified in the field and manipulated in the laboratory. We conducted a meta-analysis to test whether territory size decreases with increasing food abundance, and a mixed model analysis to test among three competing predictions: with increasing food abundance, territory size will be (1) fixed – the slope of a regression of log territory size vs. log food abundance = 0; (2) flexible and decreasing, as if individuals are defending a fixed amount of food – a slope = -1; and (3) initially compressible, but with an asymptotic minimum size – a slope between 0 and -1.We collected data from 16 studies that manipulated or measured food abundance while monitoring changes in territory size of young-of-the-year salmonids; 10 were experimental laboratory studies, whereas six were observational field studies.Overall, territory size decreased significantly with increasing food abundance; the weighted average correlation coefficient was -0.31. However, the estimated slope of the relationship between log territory size and log food abundance was only -0.23, significantly different from 0, but also significantly shallower than -1.Our estimated slope suggests that attempts to increase the density of territorial salmonids by increasing food abundance and reducing territory size will be inefficient; a 20-fold increase in food abundance would be required to double population density. Our analysis may also have implications for other species with a territorial mosaic social system – i.e. contiguous territories. In these social systems, social inertia will dampen any effects of changes in food abundance on the local density of settlers, compared to non-territorial species or those with non-contiguous territories.This article is protected by copyright. All rights reserved.
       
  • From gestation to weaning: Combining robust design and multi-event models
           unveils cost of lactation in a large herbivore
    • Abstract: The cost of current reproduction on survival or future reproduction is one of the most studied trade-offs governing resource distribution between fitness components. Results have often been clouded, however, by the existence of individual heterogeneity, with high-quality individuals able to allocate energy to several functions simultaneously, at no apparent cost.Surprisingly, it has also rarely been assessed within a breeding season by breaking down the various reproductive efforts of females from gestation to weaning, even though resource availability and energy requirements vary greatly.We filled this gap by using an intensively monitored population of Pyrenean chamois and by expanding a new methodological approach integrating robust design in a multi-event framework. We distinguished females that gave birth or not, and among reproducing females whether they lost their kid or successfully raised it until weaning. We estimated spring and summer juvenile survival, investigated whether gestation, lactation or weaning incurred costs on the next reproductive occasion, and assessed how individual heterogeneity influenced the detection of such costs.Contrary to expectations if trade-offs occur, we found a positive relationship between gestation and adult survival suggesting that non-breeding females are in poor condition. Costs of reproduction were expressed through negative relationships between lactation and both subsequent breeding probability and spring juvenile survival. Such costs could be detected only once individual heterogeneity (assessed as two groups contrasting good vs poor breeders) and time variations in juvenile survival were accounted for. Early lactation decreased the probability of future reproduction, providing quantitative evidence of the fitness cost of this period recognized as the most energetically demanding in female mammals and critical for neonatal survival.The new approach employed made it possible to estimate two components of kid survival that are often considered practically unavailable in free ranging populations, and also revealed that reproductive costs appeared only when contrasting the different stages of reproductive effort. From an evolutionary perspective, our findings stressed the importance of the temporal resolution at which reproductive cost is studied, and also provided insights on the reproductive period during which internal and external factors would be expected to have the greatest fitness impact.This article is protected by copyright. All rights reserved.
       
  • Native species dispersal reduces community invasibility by increasing
           species richness and biotic resistance
    • Abstract: 1. Recent studies indicate that diversity-invasibility relationships can depend upon spatial scale, but the contributing role of native species dispersal among local communities in mediating these relationships remains unaddressed. Metacommunity ecology highlights the effects of species dispersal rates on local diversity, thereby suggesting native species dispersal may influence local biotic resistance to invasion by non-native species. However, effects of native species dispersal rates on local native diversity and invasibility could depend upon any intraspecific differences of the invader that may alter establishment success.2. Here, I experimentally tested for the influence of native dispersal-diversity relationships on the invasibility of native communities by a non-native species represented by core, midrange, and peripheral regions of the introduced geographic range.3. In mesocosms, native plankton communities were connected by low or moderate rates of dispersal to yield dispersal-rate driven differences in native species richness prior to invasion by a non-native zooplankter, Daphnia lumholtzi. After invasion, establishment success and effects of the non-native species on native community structure and ecosystem properties were evaluated as a function of dispersal rate and invader source region relative to a control without native species.4. Native species richness was greater at the moderate dispersal rate than the low dispersal rate, and yielded a dispersal rate dependent diversity-invasibility relationship that was robust to invader source region. There was almost no establishment success of the non-native species at moderate dispersal and reduced success at low dispersal relative to the control. Invader population growth rates were negative only at the moderate dispersal rate. Effects of species dispersal on native community and ecosystem response were more influential than effects of invasion and impacts associated with invader source region.5. The results demonstrate that dispersal-diversity relationships can influence diversity-invasibility relationships at the local spatial scale. These dispersal-driven responses of invasion were unaffected by any ecological differences associated with invasion history related intraspecific variation of the non-native species. This study emphasizes that dispersal rates of native species in metacommunities can differentially alter local biotic resistance to invasion. Thus, native species dispersal rates have largely been an underappreciated local diversity maintenance mechanism that can confer insurance against biological invasions.This article is protected by copyright. All rights reserved.
       
  • Hot dogs: High ambient temperatures impact reproductive success in a
           tropical carnivore
    • Abstract: Climate change imposes an urgent need to recognise and conserve the species likely to be worst affected. However, while ecologists have mostly explored indirect effects of rising ambient temperatures on temperate and polar species, physiologists have predicted direct impacts on tropical species.The African wild dog (Lycaon pictus), a tropical species, exhibits few of the traits typically used to predict climate change vulnerability. Nevertheless, we predicted that wild dog populations might be sensitive to weather conditions, because the species shows strongly seasonal reproduction across most of its geographical range.We explored associations between weather conditions, reproductive costs, and reproductive success, drawing on long-term wild dog monitoring data from sites in Botswana (20°S, 24 years), Kenya (0°N, 12 years), and Zimbabwe (20°S, 6 years).High ambient temperatures were associated with reduced foraging time, especially during the energetically costly pup-rearing period. Across all three sites, packs which reared pups at high ambient temperatures produced fewer recruits than did those rearing pups in cooler weather; at the non-seasonal Kenya site such packs also had longer inter-birth intervals. Over time, rising ambient temperatures at the (longest-monitored) Botswana site coincided with falling wild dog recruitment.Our findings suggest a direct impact of high ambient temperatures on African wild dog demography, indicating that this species, which is already globally endangered, may be highly vulnerable to climate change. This vulnerability would have been missed by simplistic trait-based assessments, highlighting the limitations of such assessments. Seasonal reproduction, which is less common at low latitudes than at higher latitudes, might be a useful indicator of climate change vulnerability among tropical species.Climate change conjures images of polar bears and melting ice, but what happens in the tropics' African wild dogs pursue their prey long distances, and hot days offer few hours cool enough to hunt. In hotter weather, fewer pups survive. Climate change might thus spell extinction for this endangered species.
       
  • A potential pitfall in studies of biological shape: does size matter'
    • Abstract: The number of published studies using geometric morphometrics (GM) for analysing biological shape has increased steadily since the beginning of the 1990's, covering multiple research areas such as ecology, evolution, development, taxonomy and palaeontology. Unfortunately, we have observed that many published studies using GM do not evaluate the potential allometric effects of size on shape, which normally require consideration or assessment. This might lead to misinterpretations and flawed conclusions in certain cases, especially when size effects explain a large part of the shape variation.We assessed, for the first time and in a systematic manner, how often published studies that have applied GM consider the potential effects of allometry on shape.We reviewed the 300 most recent published papers that used GM for studying biological shape. We also estimated how much of the shape variation was explained by allometric effects in the reviewed papers.More than one third (38%) of the reviewed studies did not consider the allometric component of shape variation. In studies where the allometric component was taken into account, it was significant in 88% of the cases, explaining up to 87.3% of total shape variation. We believe that one reason that may cause the observed results is a misunderstanding of the process that superimposes landmark configurations, i.e. the Generalized Procrustes Analysis, which removes isometric effects of size on shape, but not allometric effects.Allometry can be a crucial component of shape variation. We urge authors to address, and report, size effects in studies of biological shape. However, we do not propose to always remove size effects, but rather to evaluate the research question with and without the allometric component of shape variation. This approach can certainly provide a thorough understanding of on how much size contributes to observed shaped variation.This article is protected by copyright. All rights reserved.
       
  • Fire influences the structure of plant-bee networks
    • Abstract: 1. Fire represents a frequent disturbance in many ecosystems, which can affect plant-pollinator assemblages and hence the services they provide. Furthermore, fire events could affect the architecture of plant-pollinator interaction networks, modifying the structure and function of communities.2. Some pollinators, such as wood-nesting bees, may be particularly affected by fire events due to damage to nesting material and its long regeneration time. However, it remains unclear whether fire influences the structure of bee plant interactions.3. Here, we used quantitative plant-wood nesting bee interaction networks sampled across four different post-fire age categories (from freshly-burnt to unburnt sites) in an arid ecosystem to test whether the abundance of wood-nesting bees, the breadth of resource use and the plant-bee community structure change along a post-fire age gradient.4. We demonstrate that freshly-burnt sites present higher abundances of generalist than specialist wood-nesting bees and this translates into lower network modularity than that of sites with greater post-fire ages. Bees do not seem to change their feeding behaviour across the post-fire age gradient despite changes in floral resource availability.5. Despite the effects of fire on plant-bee interaction network structure, these mutualistic networks seem to be able to recover a few years after the fire event. This result suggests that these interactions might be highly resilient to this type of disturbance.This article is protected by copyright. All rights reserved.
       
  • Indirect effects of ecosystem engineering combine with consumer behavior
           to determine the spatial distribution of herbivory
    • Abstract: 1.Ecosystem engineers alter environments by creating, modifying, or destroying habitats. The indirect impacts of ecosystem engineering on trophic interactions should depend on the combination of the spatial distribution of engineered structures and the foraging behavior of consumers that use these structures as refuges.2.In this study, we assessed the indirect effects of ecosystem engineering by a wood-boring beetle in a neotropical mangrove forest system. We identified herbivory patterns in a dwarf mangrove forest on the archipelago of Twin Cays, Belize.3.Past wood-boring activity impacted more than one-third of trees through the creation of tree holes that are now used, presumably as predation or thermal refuge, by the herbivorous mangrove tree crab Aratus pisonii. The presence of these refuges had a significant impact on plant-animal interactions; herbivory was more than five-fold higher on trees influenced by tree holes relative to those that were completely isolated from these refuges. Additionally, herbivory decreased exponentially with increasing distance from tree holes.4.We use individual-based simulation modeling to demonstrate that the creation of these herbivory patterns depends on a combination of the use of engineered tree holes for refuge by tree crabs, and the use of two behavior patterns in this species – site fidelity to a “home tree”, and more frequent foraging near their home tree.5.We demonstrate that understanding the spatial distribution of herbivory in this system depends on combining both the use of ecosystem engineering structures with individual behavioral patterns of herbivores.This article is protected by copyright. All rights reserved.
       
  • The index case is not enough: Variation among individuals, groups, and
           social networks modify bacterial transmission dynamics
    • 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.
       
  • Predatory birds and ants partition caterpillar prey by body size and diet
           breadth
    • Abstract: 1.The effects of predator assemblages on herbivores are predicted to depend critically on predator-predator interactions and the extent to which predators partition prey resources. The role of prey heterogeneity in generating such multiple predator effects has received limited attention.2.Vertebrate and arthropod insectivores constitute two co-dominant predatory taxa in many ecosystems, and the emergent properties of their joint effects on insect herbivores inform theory on multiple predator effects as well as biological control of insect herbivores.3.Here we use a large-scale factorial manipulation to assess the extent to which birds and ants engage in antagonistic predator-predator interactions and the consequences of heterogeneity in herbivore body size and diet breadth (i.e. the diversity of host plants used) for prey partitioning. We excluded birds and reduced ant density (by 60%) in the canopies of eight northeastern USA deciduous tree species during two consecutive years and measured the community composition and traits of lepidopteran larvae (caterpillars).4.Birds did not affect ant density, implying limited intraguild predation between these taxa in this system. Birds preyed selectively upon large-bodied caterpillars (reducing mean caterpillar length by 12%) and ants preyed selectively upon small-bodied caterpillars (increasing mean caterpillar length by 6%). Birds and ants also partitioned caterpillar prey by diet breadth. Birds reduced the frequency dietary generalist caterpillars by 24% while ants had no effect. In contrast, ants reduced the frequency of dietary specialists by 20% while birds had no effect, but these effects were non-additive; under bird exclusion, ants had no detectable effect, while in the presence of birds they reduced the frequency of specialists by 40%. As a likely result of prey partitioning by body size and diet breadth, the combined effects of birds and ants on total caterpillar density were additive, with birds and ants reducing caterpillar density by 44% and 20%, respectively.5.These results show evidence for the role of prey heterogeneity in driving functional complementarity among predators and enhanced top-down control. Heterogeneity in herbivore body size and diet breadth, as well as other prey traits, may represent key predictors of the strength of top-down control from predator communities.This article is protected by copyright. All rights reserved.
       
  • Effects of host species and environment on the skin microbiome of
           Plethodontid salamanders
    • 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.
       
  • Strategies for managing rival bacterial communities: lessons from burying
           beetles
    • 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.
       
  • Using experimentation to understand the 10-year snowshoe hare cycle in the
           boreal forest of North America
    • 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.
       
  • The microbiota of diapause: how host-microbe associations are formed after
           dormancy in an aquatic crustacean
    • 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.
       
  • Parasite-microbiota interactions potentially affect intestinal communities
           in wild mammals
    • 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.
       
  • Consequences of symbiont co-infections for insect host phenotypes
    • 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.
       
  • Differential Dispersal and the Allee Effect Create Power-Law Behavior:
           Distribution of Spot Infestations During Mountain Pine Beetle Outbreaks
    • 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.
       
  • Queen presence mediates the relationship between collective behavior and
           disease susceptibility in ant colonies
    • 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.
       
  • Desynchronizations in bee-plant interactions cause severe fitness losses
           in solitary bees
    • 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.
       
  • Gut microbial communities of American pikas (Ochotona princeps): evidence
           for phylosymbiosis and adaptations to novel diets
    • 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.
       
 
 
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