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ZOOLOGY (134 journals)                     

Showing 1 - 134 of 134 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: 157)
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: 6)
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: 4)
Anthrozoos : A Multidisciplinary Journal of The Interactions of People & Animals     Hybrid Journal   (Followers: 6)
Applied Animal Behaviour Science     Hybrid Journal   (Followers: 18)
Applied Entomology and Zoology     Partially Free   (Followers: 2)
Aquatic Mammals     Full-text available via subscription   (Followers: 8)
Aquatic Sciences     Hybrid Journal   (Followers: 12)
Arquivos de Ciências Veterinárias e Zoologia da UNIPAR     Open Access  
Arquivos de Zoologia     Open Access  
Arthropod Management Tests     Hybrid Journal   (Followers: 2)
Asian Journal of Animal and Veterinary Advances     Open Access   (Followers: 8)
Australian Journal of Zoology     Hybrid Journal   (Followers: 1)
Bangladesh Journal of Zoology     Open Access  
Bioacoustics : The International Journal of Animal Sound and its Recording     Partially Free   (Followers: 2)
Biodiversidade     Open Access  
Bird Study     Full-text available via subscription   (Followers: 26)
Brazilian Journal of Veterinary Research and Animal Science     Open Access   (Followers: 7)
British Birds     Full-text available via subscription   (Followers: 25)
Bulletin of the Museum of Comparative Zoology     Full-text available via subscription   (Followers: 2)
Canadian Journal of Animal Science     Hybrid Journal   (Followers: 3)
Canadian Journal of Zoology     Hybrid Journal   (Followers: 15)
Canadian Zooarchaeology / Zooarchéologie canadienne     Open Access  
Contributions to Zoology     Open Access   (Followers: 3)
Current Zoology     Full-text available via subscription  
Der Zoologische Garten     Full-text available via subscription   (Followers: 2)
Ecology of Freshwater Fish     Hybrid Journal   (Followers: 18)
European Journal of Taxonomy     Open Access   (Followers: 4)
Euscorpius     Open Access  
EvoDevo     Open Access   (Followers: 3)
Fish and Fisheries     Hybrid Journal   (Followers: 31)
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: 3)
Invertebrate Reproduction & Development     Hybrid Journal   (Followers: 3)
Italian Journal of Animal Science     Open Access   (Followers: 1)
Italian Journal of Zoology     Hybrid Journal   (Followers: 2)
Journal of Agrobiology     Open Access   (Followers: 3)
Journal of Animal Ecology     Hybrid Journal   (Followers: 62)
Journal of Animal Physiology and Animal Nutrition     Hybrid Journal   (Followers: 5)
Journal of Apicultural Science     Open Access   (Followers: 2)
Journal of Applied Animal Research     Hybrid Journal   (Followers: 3)
Journal of Basic & Applied Zoology : Physiology     Open Access   (Followers: 2)
Journal of Experimental Zoology Part A: Ecological Genetics and Physiology     Hybrid Journal   (Followers: 4)
Journal of Experimental Zoology Part B : Molecular and Developmental Evolution     Hybrid Journal   (Followers: 2)
Journal of Freshwater Ecology     Hybrid Journal   (Followers: 13)
Journal of Herpetology     Full-text available via subscription   (Followers: 13)
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: 36)
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: 1)
New Zealand Journal of Zoology     Hybrid Journal   (Followers: 7)
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: 18)
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: 4)
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: 9)
World Rabbit Science     Open Access  
Zoo Biology     Hybrid Journal   (Followers: 9)
Zoo Indonesia : Jurnal Fauna Tropika     Open Access  
ZooKeys     Open Access   (Followers: 5)
Zoologia (Curitiba)     Open Access   (Followers: 1)
Zoologica Poloniae : The Journal of Polish Zoological Society     Open Access   (Followers: 1)
Zoologica Scripta     Hybrid Journal   (Followers: 3)
Zoological Journal of the Linnean Society     Hybrid Journal   (Followers: 12)
Zoological Letters     Open Access  
Zoological Science     Full-text available via subscription   (Followers: 2)
Zoological Studies     Open Access   (Followers: 1)
Zoologische Mededelingen     Open Access  
Zoologischer Anzeiger - A Journal of Comparative Zoology     Hybrid Journal   (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]   [62 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  [1577 journals]
  • An Arctic predator-prey system in flux: climate change impacts on coastal
           space use by polar bears and ringed seals
    • Authors: Charmain D. Hamilton; Kit M. Kovacs, Rolf A. Ims, Jon Aars, Christian Lydersen
      Abstract: 1.Climate change is impacting different species at different rates, leading to alterations in biological interactions with ramifications for wider ecosystem functioning. Understanding these alterations can help improve predictive capacity and inform management efforts designed to mitigate against negative impacts.2.We investigated how the movement and space use patterns of polar bears (Ursus maritimus) in coastal areas in Svalbard, Norway, have been altered by a sudden decline in sea ice that occurred in 2006. We also investigated whether the spatial overlap between polar bears and their traditionally most important prey, ringed seals (Pusa hispida), has been affected by the sea-ice decline, as polar bears are dependent on a sea-ice platform for hunting seals.3.We attached biotelemetry devices to ringed seals (n=60, both sexes) and polar bears (n=67, all females) before (2002-2004) and after (2010-2013) a sudden decline in sea ice in Svalbard. We used linear mixed-effects models to evaluate the association of these species to environmental features and an approach based on Time Spent in Area to investigate changes in spatial overlap between the two species.4.Following the sea-ice reduction, polar bears spent the same amount of time close to tidal glacier fronts in the spring but less time in these areas during the summer and autumn. However, ringed seals did not alter their association with glacier fronts during summer, leading to a major decrease in spatial overlap values between these species in Svalbard's coastal areas. Polar bears now move greater distances daily and spend more time close to ground-nesting bird colonies, where bear predation can have substantial local effects.5.Our results indicate that sea-ice declines have impacted the degree of spatial overlap and hence the strength of the predator-prey relationship between polar bears and ringed seals, with consequences for the wider Arctic marine and terrestrial ecosystems. Shifts in ecological interactions are likely to become more widespread in many ecosystems as both predators and prey respond to changing environmental conditions induced by global warming, highlighting the importance of multi-species studies.This article is protected by copyright. All rights reserved.
      PubDate: 2017-04-17T15:40:25.689593-05:
      DOI: 10.1111/1365-2656.12685
  • 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
    • 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
  • 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.
  • Stay-at-home strategy brings fitness benefits to migrants
    • Abstract: In Focus: Lok, T., Veldhoen, L., Overdijk, O., Tinbergen, J. M., & Piersma, T. (2017). An age-dependent fitness cost of migration' Old trans-Saharan migrating spoonbills breed later than those staying in Europe, and late breeders have lower recruitment. Journal of Animal Ecology, 86, 998–1009.In Focus: Grist, H., Daunt, F., Wanless, S., Burthe, S. J., Newell, M. A., Harris, M. P., & Reid, J. M. (2017). Reproductive performance of resident and migrant males, females and pairs in a partially migratory bird. Journal of Animal Ecology, 86, 1010–1021.In this issue, two studies examine the extent to which variation in migratory behaviour influences individual fitness across a population. Lok, Veldhoen, Overdijk, Tinbergen, and Piersma () examine reproductive success and post-fledging survival in a population of Eurasian spoonbills (Platalea leucorodia), comparing individuals that winter in south-west Europe against those migrating to sub-Saharan Africa, while Grist et al. () measure reproductive success in a population of European shags (Phalacrocorax aristotelis) breeding in Scotland that either remain resident or migrate to surrounding waters. Both studies find that individuals migrating longer distances tend to show later initiation of breeding attempts. In turn, longer migration correlates with lower reproductive success in both populations. In spoonbills, this effect is most pronounced in older male birds, while young individuals show little difference in breeding success with respect to migration distance. In shags, fitness benefits of residence were most pronounced when both individuals of a pair were resident, although there was no evidence of assortative mating. Both studies provide fascinating new insights into the role migratory variability can play in shaping population dynamics.Variation in migratory behaviour can be an important driver of differences in individual fitness across populations. Two studies in this issue examine how reproductive success varies in relation to migratory strategy, revealing how shorter migration (or even residence) can confer fitness benefits in migratory birds, mediated by earlier breeding initiation relative to individuals that travel further afield.
  • 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.
  • Influence of predation on community resilience to disease
    • Abstract: Outbreaks of generalist pathogens are influenced by host community structure, including population density and species diversity. Within host communities predation can influence pathogen transmission rates, prevalence and impacts. However, the influence of predation on community resilience to outbreaks of generalist pathogens is not fully understood.The role of predation on host community resilience to disease was assessed using an epidemiological multi-host susceptible-exposed-infectious-recovered model. Sphaerothecum destruens, an emerging fungal-like generalist pathogen, was used as a model pathogen. Six cyprinid and salmonid fishes, including an asymptomatic carrier, were selected as model hosts that are known to be impacted by S. destruens, and they were used within a model host community.Pathogen release into the host community was via introduction of the asymptomatic carrier. Mortality from infection, pathogen incubation rate, and host recovery rate were set to a range of evidence-based values in each species and were varied in secondary consumers to predict top-down effects of infection on the resilience of a host community. Predation pressure within the fish community was varied to test its effects on infection prevalence and host survival in the community.Model predictions suggested that predation of the asymptomatic hosts by fishes in the host community was insufficient to eliminate S. destruens. Sphaerothecum destruens persisted in the community due to its rapid transmission from the asymptomatic host to susceptible host fishes. Following transmission, pathogen prevalence in the community was driven by transmission within and between susceptible host fishes, indicating low host community resilience. However, introducing low densities of a highly specific piscivorous fish into the community to pre-date asymptomatic hosts could limit pathogen prevalence in the host community, thus increasing resilience.The model predictions indicate that whilst resilience to this generalist pathogen in the host community was low, this could be increased using management interventions. The results suggest that this model has high utility for predicting community resilience to disease and thus can be applied to other generalist parasites to determine risks of disease emergence.This paper combines several extensive datasets of detailed infection data on a generalist pathogen to create a multi-host epidemiological model. The model is applicable to management and conservation scenarios and is reliable due to its basis on experimental data. Furthermore, the authors propose mathematical links between epidemiological parameters in the model which is often very difficult to characterise for multi-host pathogens. This can help in predicting outbreaks and effects of the pathogen even in novel hosts where data are unavailable.
  • 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
    • 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
    • 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.
  • Life histories and conservation of long-lived reptiles, an illustration
           with the American Crocodile (Crocodylus acutus)
    • Abstract: Successful species conservation is dependent on adequate estimates of population dynamics, but age-specific demographics are generally lacking for many long-lived iteroparous species such as large reptiles. Accurate demographic information allows estimation of population growth rate, as well as projection of future population sizes and quantitative analyses of fitness trade-offs involved in evolution of life-history strategies.Here, a long-term capture-recapture study was conducted from 1978-2014 on the American crocodile (Crocodylus acutus) in southern Florida. Over the study period, 7,427 hatchlings were marked and 380 individuals were recaptured for as many as 25 years. We estimated survival to be strongly age-dependent with hatchlings having the lowest survival rates (16%) but increasing to nearly 90% at adulthood based on mark-recapture models. More than 5% of the female population were predicted to be reproductive by age 8 years; the age-specific proportion of reproductive females steadily increased until age 18 when more than 95% of females were predicted to be reproductive. Population growth rate, estimated from a Leslie-Lefkovich stage-class model, showed a positive annual growth rate of 4% over the study period.Using a prospective sensitivity analysis, we revealed that the adult stage, as expected was the most critical stage for population growth rate; however, the survival of younger crocodiles before they became reproductive, also had a surprisingly high elasticity. We found that variation in age-specific fecundity has very limited impact on population growth rate in American crocodiles.We used a comparative approach to show that the original life history strategy of American crocodiles is actually shared by other large, long-lived reptiles: while adult survival rates always have a large impact on population growth, this decreases with declining growth rates, in favor of a higher elasticity of the juvenile stage.Crocodiles, as a long-lived and highly fecund species deviate from the usual association of life-histories of “slow” species. Current management practices are focused on nests and hatchling survival; however, protection efforts that extend to juvenile crocodiles would be most effective for conservation of the species, especially in an ever-developing landscape.This article is protected by copyright. All rights reserved.
  • Niche conservatism and the invasive potential of the wild boar
    • Abstract: 1.Niche conservatism, i.e. the retention of a species’ fundamental niche through evolutionary time, is cornerstone for biological invasion assessments. The fact that species tend to maintain their original climate niche allows predictive maps of invasion risk to anticipate potential invadable areas. Unraveling the mechanisms driving niche shifts can shed light on the management of invasive species.2.Here, we assessed niche shifts in one of the world's worst invasive species: the wild boar Sus scrofa. We also predicted potential invadable areas based on an ensemble of three ecological niche modeling methods, and evaluated the performance of models calibrated with native vs pooled (native plus invaded) species records. By disentangling the drivers of change on the exotic wild boar population's niches, we found strong evidence for niche conservatism during biological invasion.3.Ecological niche models calibrated with both native and pooled range records predicted convergent areas. Also, observed niche shifts are mostly explained by niche unfilling, i.e. there are unoccupied areas in the exotic range where climate is analogous to the native range.4.Niche unfilling is expected as result of recent colonization and ongoing dispersal, and was potentially stronger for the Neotropics, where a recent wave of introductions for pig-farming and game-hunting has led to high wild boar population growth rates. The invasive potential of wild boar in the Neotropics is probably higher than in other regions, which has profound management implications if we are to prevent their invasion into species-rich areas, such as Amazonia, coupled with expansion of African swine fever and possibly great economic losses.5.Although the originally Eurasian-wide distribution suggests a pre-adaptation to a wide array of climates, the wild boar worldwide invasion does not exhibit evidence of niche evolution. The invasive potential of the wild boar therefore probably lies on the reproductive, dietary and morphological characteristics of this species, coupled with behavioral thermoregulation.This article is protected by copyright. All rights reserved.
  • Boldness predicts an individual's position along an
           exploration-exploitation foraging trade-off
    • Abstract: Individuals do not have complete information about the environment and therefore they face a trade-off between gathering information (exploration) and gathering resources (exploitation). Studies have shown individual differences in components of this trade-off but how stable these strategies are in a population and the intrinsic drivers of these differences is not well understood.Top marine predators are expected to experience a particularly strong trade-off as many species have large foraging ranges and their prey often have a patchy distribution. This environment leads these species to exhibit pronounced exploration and exploitation phases but differences between individuals are poorly resolved. Personality differences are known to be important in foraging behaviour but also in the trade-off between exploration and exploitation. Here we test whether personality predicts an individual exploration-exploitation strategy using wide ranging wandering albatrosses (Diomedea exulans) as a model system.Using GPS tracking data from 276 wandering albatrosses, we extract foraging parameters indicative of exploration (searching) and exploitation (foraging) and show that foraging effort, time in patch and size of patch are strongly correlated, demonstrating these are indicative of an exploration-exploitation strategy. Furthermore, we show these are consistent within individuals and appear stable in the population, with no reproductive advantage.The searching and foraging behaviour of bolder birds placed them towards the exploration end of the trade-off, whereas shy birds showed greater exploitation. This result provides a mechanism through which individual foraging strategies may emerge. Age and sex affected components of the trade-off, but not the trade-off itself, suggesting these factors may drive behavioural compensation to maintain resource acquisition and this was supported by the evidence that there were no fitness consequence of any EE trait nor the trade-off itself.These results demonstrate a clear trade-off between information gathering and exploitation of prey patches, and reveals for the first time that boldness may drive these differences. This provides a mechanism through which widely reported links between personality and foraging may emerge. 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.
  • Pulsed food resources, but not forest cover, determines lifetime
           reproductive success in a forest-dwelling rodent
    • Abstract: 1.The relative contributions of habitat and food availability on fitness may provide evidence for key habitat features needed to safeguard population persistence. However, defining habitat quality for a species can be a complex task, especially if knowledge on the relationship between individual performance and habitat quality is lacking.2.Here, we determined the relative importance of availability of suitable forest habitat, body mass, and food from masting tree species on female lifetime reproductive success (LRS) of Siberian flying squirrels (Pteromys volans).3.We calculated LRS of 500 female flying squirrels based on a 22 year-long longitudinal data set of two populations from western Finland. We assessed with generalised additive models the potential effects of availability of suitable habitat and cumulative lifetime availability of food from masting tree species on female LRS, longevity and fecundity. On a reduced dataset, we evaluated the importance of female winter body mass and conducted a piecewise path analysis to determine how variables were connected.4.According to generalised additive models female longevity, fecundity and LRS were mainly determined by variation in cumulative lifetime availability of food from masting alder and birch. Instead, habitat and body mass had smaller role. The path analysis indicated that lifetime food availability had direct effect on longevity and fecundity, and these had equal effect on LRS at both study sites.5.Our results on LRS shows that the occurrence of tree masting events during a flying squirrel female's lifetime have profoundly larger effect on lifetime reproductive success than the cover of suitable forest habitat. Furthermore, this study emphasises the importance of both fecundity and longevity, and the indirect effects of food availability via those components, as determinants of lifetime fitness of female flying squirrels.This article is protected by copyright. All rights reserved.
  • Thermal phsyiology: A new dimension of the pace-of-life syndrome
    • Abstract: 1.Current syndrome research focuses primarily on behavior with few incorporating components of physiology. One such syndrome is the Pace-of-Life Syndrome (POLS) which describes covariation between behaviour, metabolism immunity, hormonal response, and life history traits. Despite the strong effect temperature has on behavior, thermal physiology has yet to be considered within this syndrome framework.2.We proposed the POLS to be extended to include a new dimension, the cold-hot axis. Under this premise, it is predicted that thermal physiology and behavior would covary whereby individual positioning along the thermal continuum would coincide with that of the behavioral continuum.3.This hypothesis was tested by measuring thermal traits of delicate skinks (Lampropholis delicata) and linking it to their behavior. Principal components analysis and structural equation modelling were used to determine if traits were structured within the Pace-of-Life Syndrome (POLS) and to characterize the direction of their interactions.4.Model results supported the inclusion of the cold-hot axis into the POLS and indicated that thermal physiology was the driver of this relationship, in that thermal traits either constrained or promoted activity, exploration, boldness, and social behavior.5.This study highlights the need to integrate thermal physiology within a syndrome framework.This article is protected by copyright. All rights reserved.
  • Corrigendum
  • Partial diel migration: a facultative migration underpinned by long-term
           inter-individual variation
    • Abstract: 1.The variation in migration that comprise partial diel migrations, putatively occur entirely as a consequence of behavioural flexibility. However, seasonal partial migrations are increasingly recognised to be mediated by a combination of reversible plasticity in response to environmental variation and individual variation due to genetic and environmental effects.2.Here we test the hypothesis that while partial diel migration heterogeneity occurs primarily due to short-term within-individual flexibility in behaviour, long-term individual differences in migratory behaviour also underpin this migration variation.3.Specifically, we use a hierarchical behavioural reaction norm approach to partition within- and among-individual variation in depth use and diel plasticity in depth use, across short- and long-term time-scales, in a group of 47 burbot (Lota lota) tagged with depth-sensing acoustic telemetry transmitters.4.We found that within-individual variation at the among-days-within-seasons and among-seasons scale, explained the dominant proportion of phenotypic variation. However, individuals also repeatedly differed in their expression of migration behaviour over the two year study duration.5.These results reveal that diel migration variation occurs primarily due to short-term within-individual flexibility in depth use and diel migration behaviour. However, repeatable individual differences also played a key role in mediating partial diel migration.6.These findings represent a significant advancement of our understanding of the mechanisms generating the important,yet poorly understood phenomena of partial diel migration. Moreover, given the pervasive occurrence of diel migrations across aquatic taxa, these findings indicate that individual differences have an important, yet previously unacknowledged role in structuring the temporal and vertical dynamics of aquatic ecosystems.This article is protected by copyright. All rights reserved.
  • Carnivore carcasses are avoided by carnivores
    • Abstract: 1. Ecologists have traditionally focused on herbivore carcasses as study models in scavenging research. However, some observations of scavengers avoiding feeding on carnivore carrion suggest that different types of carrion may lead to differential pressures. Untested assumptions about carrion produced at different trophic levels could therefore lead ecologists to overlook important evolutionary processes and their ecological consequences.2. Our general goal was to investigate the use of mammalian carnivore carrion by vertebrate scavengers. In particular, we aimed to test the hypothesis that carnivore carcasses are avoided by other carnivores, especially at the intra-specific level, most likely to reduce exposure to parasitism.3. We take a three-pronged approach to study this principle by: i) providing data from field experiments, ii) carrying out evolutionary simulations of carnivore scavenging strategies under risks of parasitic infection, and iii) conducting a literature-review to test two hypotheses regarding parasite life-history strategies.4. First, our field experiments showed that the mean number of species observed feeding at carcasses and the percentage of consumed carrion biomass were substantially higher at herbivore carcasses than at carnivore carcasses. This occurred even though the number of scavenger species visiting carcasses and the time needed by scavengers to detect carcasses were similar between both types of carcasses. In addition, we did not observe cannibalism. Second, our evolutionary simulations demonstrated that a risk of parasite transmission leads to the evolution of scavengers with generally low cannibalistic tendencies, and that the emergence of cannibalism-avoidance behavior depends strongly on assumptions about parasite-based mortality rates. Third, our literature review indicated that parasite species potentially able to follow a carnivore–carnivore indirect cycle, as well as those transmitted via meat consumption, are rare in our study system.5. Our findings support the existence of a novel coevolutionary relation between carnivores and their parasites, and suggest that carnivore and herbivore carcasses play very different roles in food webs and ecosystems.This article is protected by copyright. All rights reserved.
  • Flexibility in the duration of parental care: female leopards prioritise
           cub survival over reproductive output
    • Abstract: 1.Deciding when to terminate care of offspring is a key consideration for parents. Prolonging care may increase fitness of current offspring, but it can also reduce opportunities for future reproduction. Despite its evolutionary importance, few studies have explored the optimal duration of parental care, particularly among large carnivores.2.We used a 40-year dataset to assess the trade-offs associated with the length of maternal care in leopards in the Sabi Sand Game Reserve, South Africa. We compared the costs imposed by care on the survival and residual reproductive value of leopard mothers against the benefits derived from maternal care in terms of increased offspring survival, recruitment and reproduction. We also examined the demographic and ecological factors affecting the duration of care in light of five explanatory hypotheses: litter-size, sex-allocation, resource-limitation, timing-of-independence, and terminal-investment.3.Duration of care exhibited by female leopards varied markedly, from 9–35 months. Mothers did not appear to suffer any short- or long-term survival costs from caring for cubs, but extending care reduced the number of litters that mothers could produce during their lifetimes. Interestingly, the duration of care did not appear to affect the post-independence survival or reproductive success of offspring (although it may have indirectly affected offspring survival by influencing dispersal distance). However, results from generalised linear mixed models showed that mothers prolonged care during periods of prey scarcity, supporting the resource-limitation hypothesis. Female leopards also cared for sons longer than daughters, in line with the sex-allocation hypothesis.4.Cub survival is an important determinant of the lifetime reproductive success in leopards. By buffering offspring against environmental perturbation without jeopardizing their own survivorship, female leopards apparently ‘hedge their bets’ with current offspring rather than gamble on future offspring which have a small probability of surviving.5.In many species, parents put their own needs before that of their offspring. Leopard mothers appear sensitive to their offspring's demands, and adjust levels of care accordingly.This article is protected by copyright. All rights reserved.
  • Advancing research on animal-transported subsidies by integrating animal
           movement and ecosystem modeling
    • Abstract: 1.Connections between ecosystems via animals (active subsidies) support ecosystem services and contribute to numerous ecological effects. Thus, the ability to predict the spatial distribution of active subsidies would be useful for ecology and conservation.2.Previous work modeling active subsidies focused on implicit space or static distributions, which treat passive and active subsidies similarly. Active subsidies are fundamentally different from passive subsidies, because animals can respond to the process of subsidy deposition and ecosystem changes caused by subsidy deposition.3.We propose addressing this disparity by integrating animal movement and ecosystem ecology to advance active subsidy investigations, make more accurate predictions of subsidy spatial distributions, and enable a mechanistic understanding of subsidy spatial distributions.4.We review selected quantitative techniques that could be used to accomplish integration and lead to novel insights. The ultimate objective for these types of studies is predictions of subsidy spatial distributions from characteristics of the subsidy and the movement strategy employed by animals that transport subsidies. These advances will be critical in informing the management of ecosystem services, species conservation, and ecosystem degradation related to active subsidies.This article is protected by copyright. All rights reserved.
  • Contrasting drivers of reproductive ageing in albatrosses
    • Abstract: 1.Age-related variation in reproductive performance is ubiquitous in wild vertebrate populations and has important consequences for population and evolutionary dynamics.2.The ageing trajectory is shaped by both within-individual processes, such as improvement and senescence, and by the among-individual effects of selective appearance and disappearance. To date, few studies have compared the role of these different drivers among species or populations.3.In this study, we use nearly 40 years of longitudinal monitoring data to contrast the within- and among-individual processes contributing to the reproductive ageing patterns in three albatross species (two biennial and one annual breeder), and test whether these can be explained by differences in life-histories.4.Early life performance in all species increased with age, and was predominantly influenced by within-individual improvements. However, reproductive senescence was detected in only two of the species. In the species exhibiting senescent declines, we also detected a terminal improvement in breeding success. This is suggestive of a trade-off between reproduction and survival, which was supported by evidence of selective disappearance of good breeders.5.We demonstrate that comparisons of closely-related species which differ in specific aspects of their life-history can shed light on the ecological and evolutionary forces shaping variation in ageing patterns.This article is protected by copyright. All rights reserved.
  • Reorganization of interaction networks modulates the persistence of
           species in late successional stages
    • Abstract: 1.Ecological interaction networks constantly reorganize as interspecific interactions change across successional stages and environmental gradients. This reorganization can also be associated with the extent to which species change their preference for types of niches available in their local sites. Despite the pervasiveness of these interaction changes, previous studies have revealed that network reorganizations have a minimal or insignificant effect on global descriptors of network architecture, such as: connectance, modularity, and nestedness. However, little is known about whether these reorganizations may have an effect on community dynamics and composition.2.To answer the question above, we study the multi-year dynamics and reorganization of plant-herbivore interaction networks across secondary successional stages of a tropical dry forest. We develop new quantitative tools based on a structural stability approach to estimate the potential impact of network reorganization on species persistence. Then, we investigate whether this impact can explain the likelihood of persistence of herbivore species in the observed communities.3.We find that resident (early-arriving) herbivore species increase their likelihood of persistence across time and successional stages. Importantly, we demonstrate that, in late successional stages, the reorganization of interactions among resident species has a strong inhibitory effect on the likelihood of persistence of colonizing (late-arriving) herbivores.4.These findings support earlier predictions suggesting that, in mature communities, changes of species interactions can act as community-control mechanisms (also known as priority effects). Furthermore, our results illustrate that the dynamics and composition of ecological communities cannot be fully understood without attention to their reorganization processes, despite the invariability of global network properties.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.
  • Effects of breeder turnover and harvest on group composition and
           recruitment in a social carnivore
    • Abstract: 1.Breeder turnover can influence population growth in social carnivores through changes to group size, composition, and recruitment.2.Studies that possess detailed group composition data that can provide insights about the effects of breeder turnover on groups have generally been conducted on species that are not subject to recurrent annual human harvest. We wanted to know how breeder turnover affects group composition and how harvest, in turn, affects breeder turnover in cooperatively breeding gray wolves (Canis lupus Linnaeus 1758).3.We used noninvasive genetic sampling at wolf rendezvous sites to construct pedigrees and estimate recruitment in groups of wolves before and after harvest in Idaho, USA.4.Turnover of breeding females increased polygamy and potential recruits per group by providing breeding opportunities for subordinates although resultant group size was unaffected one year after the turnover. Breeder turnover had no effect on the number of nonbreeding helpers per group. After breeding male turnover, fewer female pups were recruited in the new males’ litters. Harvest had no effect on the frequency of breeder turnover.5.We found that breeder turnover led to shifts in the reproductive hierarchies within groups and the resulting changes to group composition were quite variable and depended on the sex of the breeder lost. We hypothesize that nonbreeding females direct help away from non-kin female pups to preserve future breeding opportunities for themselves. Breeder turnover had marked effects on the breeding opportunities of subordinates and the number and sex ratios of subsequent litters of pups. Seemingly subtle changes to groups, such as the loss of 1 individual, can greatly affect group composition, genetic content, and short-term population growth when the individual lost is a breeder.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.
  • An age-dependent fitness cost of migration' Old trans-Saharan
           migrating spoonbills breed later than those staying in Europe, and late
           breeders have lower recruitment
    • Abstract: Migration is a widespread phenomenon in the animal kingdom. On the basis of the considerable variation that exists between and within species, and even within populations, we may be able to infer the (age- and sex-specific) ecological trade-offs and constraints moulding migration systems from assessments of fitness associated with migration and wintering in different areas.During three consecutive breeding seasons, we compared the reproductive performance (timing of breeding, breeding success, chick body condition and post-fledging survival) of Eurasian spoonbills Platalea leucorodia that breed at a single breeding site in The Netherlands, but migrate different distances (ca. 4,500 km versus 2,000 km, either or not crossing the Sahara) to and from wintering areas in southern Europe and West Africa. Using mark-recapture analysis, we further investigated whether survival until adulthood (recruitment probability) of chicks hatched between 2006 and 2010 was related to their hatch date and body condition.Long-distance migrants bred later, particularly the males, and raised chicks of poorer body condition than short-distance migrants. Hatch dates strongly advanced with increasing age in short-distance migrants, but hardly advanced in long-distance migrants, causing the difference in timing of breeding between long- and short-distance migrants to be more pronounced among older birds.Breeding success and chick body condition decreased over the season, and chicks that fledged late in the season or in poor condition were less likely to survive until adulthood. As a result, long-distance migrants – particularly the males and older birds – likely recruit fewer offspring into the breeding population than short-distance migrants. This inference is important for predicting the population-level consequences of changes in winter habitat suitability throughout the wintering range.Assuming that the long-distance migrants – being the birds that occupy the traditional wintering areas – are not the poorer quality birds, and that the observed age-dependent patterns in timing of breeding are driven by within-individual effects and not by selective disappearance, our results suggest that the strategy of long-distance migration, involving the crossing of the Sahara to winter in West Africa, incurred a cost by reducing reproductive output, albeit a cost paid only later in life.This article is protected by copyright. All rights reserved.
  • Estimating demographic contributions to effective population size in an
           age-structured wild population experiencing environmental and demographic
    • Abstract: 1.A population's effective size (Ne) is a key parameter that shapes rates of inbreeding and loss of genetic diversity, thereby influencing evolutionary processes and population viability. However estimating Ne, and identifying key demographic mechanisms that underlie the Ne to census population size (N) ratio, remains challenging, especially for small populations with overlapping generations and substantial environmental and demographic stochasticity and hence dynamic age-structure.2.A sophisticated demographic method of estimating Ne/N, which uses Fisher's reproductive value to account for dynamic age-structure, has been formulated. However this method requires detailed individual- and population-level data on sex- and age-specific reproduction and survival, and has rarely been implemented.3.Here we use the reproductive value method and detailed demographic data to estimate Ne/N for a small and apparently isolated red-billed chough (Pyrrhocorax pyrrhocorax) population of high conservation concern. We additionally calculated two single-sample molecular genetic estimates of Ne to corroborate the demographic estimate and examine evidence for unobserved immigration and gene flow.4.The demographic estimate of Ne/N was 0.21, reflecting a high total demographic variance (σ2dg) of 0.71. Females and males made similar overall contributions to σ2dg. However, contributions varied among sex-age classes, with greater contributions from 3 year-old females than males, but greater contributions from ≥5 year-old males than females.5.The demographic estimate of Ne was ~30, suggesting that rates of increase of inbreeding and loss of genetic variation per generation will be relatively high. Molecular genetic estimates of Ne computed from linkage disequilibrium and approximate Bayesian computation were approximately 50 and 30 respectively, providing no evidence of substantial unobserved immigration which could bias demographic estimates of Ne.6. Our analyses identify key sex-age classes contributing to demographic variance and thus decreasing Ne/N in a small age-structured population inhabiting a variable environment. They thereby demonstrate how assessments of Ne can incorporate stochastic sex- and age-specific demography and elucidate key demographic processes affecting a population's evolutionary trajectory and viability. Furthermore, our analyses show that Ne for the focal chough population is critically small, implying that management to re-establish genetic connectivity may be required to ensure population viability.This article is protected by copyright. All rights reserved.
  • Diverse responses of species to landscape fragmentation in a simple food
    • Abstract: 1.Habitat destruction, characterized by habitat loss and fragmentation, is a key driver of species extinction in spatial extended communities. Recently, there has been some progress in the theory of spatial food webs, however to date practically little is known about how habitat configurational fragmentation influences multi-trophic food web dynamics.2.To explore how habitat fragmentation affects species persistence in food webs, we introduce a modelling framework that describes the site occupancy of species in a tri-trophic system. We assume that species dispersal range increases with trophic level, exploiting pair-approximation techniques to describe the effect of habitat clustering.3.In accordance with the trophic rank hypothesis, both habitat loss and fragmentation generally cause species extinction, with stronger effects occurring at higher trophic levels. However, species display diverse responses (negative, neutral or positive) to habitat loss and fragmentation separately, depending on their dispersal range and trophic position.4.Counter-intuitively, prey species may benefit from habitat loss due to a release in top-down control. Similarly, habitat fragmentation has almost no influence on the site occupancy of the intermediate consumer in the tri-trophic system, though it decreases those of both basal species and top predator. Consequently, species’ responses to habitat destruction vary as other species become extinct.5.Our results reiterate the importance of the interplay between bottom-up and top-down control in trophically linked communities, and highlight the complex responses occurring in even a simple food chain.This article is protected by copyright. All rights reserved.
  • Shallow size-density relations within mammal clades suggest greater
           intra-guild ecological impact of large-bodied species
    • Abstract: 1.Population densities of species have a predictable relationship to their body mass on a global scale. This relationship is known as the size-density relationship. The relationship was originally found to be directly opposite of metabolic rate scaling, which led to the hypothesis of energetic equivalence. However, recent studies have suggested that the size-density relationship varies between clades. Specifically, the size-density relationship for certain mammal clades has been found to be less negative than the relationship across all mammals.2.The aim of the present study is to estimate phylogenetic variation in the scaling relationship, using a data-driven identification of natural phylogenetic substructure in the body size-density relation, and discuss its potential drivers. The classic model is often used to estimate natural population densities, and a further, practical aim is to improve it by incorporating variability among phylogenetic groups.3.We expand the model for the size-density relationship relation of mammals to include clade-specific variation. We used a dataset with population and body mass estimates of 924 terrestrial mammal species, covering 97 families, and applied an algorithm identifying group-specific changes in the relationship across a family-level phylogeny.4.We show increased performance in species density estimation is achieved by incorporating clade-specific changes in the relationship compared to the classic model (increasing r2 from 0.56 to 0.74 and ΔAICc = 466). While the global size-density relationship across clades was confirmed to be similar to previous findings (r = -0.74); the relationship within all sub-clades was less negative than the overall trend.5.Our results show that data-driven identification of phylogenetic substructure in the size-density relation substantially improves predictive accuracy of the model. The less negative relationship within clades compared to the overall trend and compared to within clade metabolic scaling suggest that the energetic equivalence rule does not hold. This relationship shows that large species within clades use proportionally more energy than smaller species. Therefore, our results are consistent with a greater intra-guild ecological impact of large-bodied species via partial monopolisation of resources by the largest species of a given guild, and hence size-asymmetric intra-guild competition.This article is protected by copyright. All rights reserved.
  • Environmental constraints on the compositional and phylogenetic
           beta-diversity of tropical forest snake assemblages
    • Abstract: The ongoing biodiversity crisis increases the importance and urgency of studies addressing the role of environmental variation on the composition and evolutionary history of species assemblages, but especially the tropics and ectotherms remain understudied.In regions with rainy summers, coexistence of ectothermic species may be determined by the partitioning of the climatic niche, since ectotherms can rely on water availability and thermoregulatory behaviour to buffer constraints along their climatic niche. Conversely, ectotherms facing dry summers would have fewer opportunities to climatic niche partitioning and other processes rather than environmental filtering would mediate species coexistence.We used 218 snake assemblages to quantify the compositional (CBD) and phylogenetic (PBD) beta-diversity of snakes in the Atlantic Forest (AF) hotspot. We identify two AF regions with distinct climatological regimes: dry summers in the northern-AF and rainy summers in the southern-AF. While accounting for the influence of multiscale spatial processes, we disentangle the relative contribution of thermal, water-related, and topographic conditions in structuring the CBD and PBD of snake assemblages, and determine the extent in which snake assemblages under distinct climatological regimes are affected by environmental filtering.Thermal conditions best explain CBD and PBD of snakes for the whole AF, whereas water-related factors best explain the structure of snake assemblages within a same climatological regime. CBD and PBD patterns are similarly explained by spatial factors but snake assemblages facing dry summers are more affected by spatial processes operating at fine to intermediate spatial scale whereas those assemblages in regions with rainy summers have a stronger signature of coarser-scale processes. As expected, environmental filtering plays a stronger role in southern-AF than northern-AF, and the synergism between thermal and water-related conditions is the key cause behind this difference.Differences in climatological regimes within the tropics may affect processes mediating species coexistence. The role of broad-scale gradients (e.g. temperature, precipitation) in structuring tropical ectothermic assemblages is greater in regions with rainy summers where climatic niche partitioning is more likely. Our findings highlight the potential stronger role of biotic interactions and neutral processes in structuring ectothermic assemblages facing changes towards warmer and dryer climates.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.
  • Mechanisms and implications of a type IV functional response for
           short-term intake rate of dry matter in large mammalian herbivores
    • Abstract: 1.The functional response (i.e. the relationship between consumers’ intake rate and resource density) is central in plant-herbivore interactions. Its shape and the biological processes leading to it have significant implications for both foraging theory and ecology of grazing systems.2.A type IV functional response (i.e. dome-shaped relationship) of short-term intake rate of dry matter (intake while grazing) has rarely been reported for large herbivores and the conditions that can lead to it are poorly understood.3.We report a type IV functional response observed in heifers grazing monocultures of Cynodon sp. and Avena strigosa. The mechanisms and consequences of this type of functional response for grazed system dynamics are discussed.4.Intake rate was higher at intermediate than at short or tall sward heights in both grass species. The type IV functional response resulted from changes in bite mass instead of a longer time needed to encounter and process bites. Thus, the decrease of intake rate of dry matter in tall swards is not explained by a shift from process 3 (potential bites are concentrated and apparent) to process 2 (potential bites are apparent but dispersed, Spalinger & Hobbs 1992). Bite mass was smaller in tall than in intermediate swards due to a reduction of bite volume possibly caused by the greater proportion of stem and sheath acting as a physical barrier to bite formation.5.It is generally accepted that potential bites are abundant and apparent in most grassland and meadow systems, as they were in the present experiments. Therefore, a type IV response of intake rate not directly related to digestive constraints may determine the dynamics of intake and defoliation under a much larger set of conditions than previously thought. These results have implications for foraging theory and stability of grazing systems. For example, if animals prefer patches of intermediate stature that yield the highest intake rate, grazing should lead to the widely observed bimodal distribution of plant mass per unit area, even when tall patches are not of significantly lower digestive quality than the pasture average.This article is protected by copyright. All rights reserved.
  • Context dependent colonization dynamics: regional reward contagion drives
           local compression in aquatic beetles
    • Abstract: 1.Habitat selection by colonizing organisms is an important factor in determining species abundance and community dynamics at multiple spatial scales. Many organisms select habitat patches based on intrinsic patch quality, but patches exist in complex landscapes linked by dispersal and colonization, forming metapopulations and metacommunities. Perceived patch quality can be influenced by neighboring patches through spatial contagion, wherein perceived quality of one patch can extend beyond its borders and either increase or decrease the colonization of neighboring patches and localities. These spatially-explicit colonization dynamics can result in habitat compression, wherein more colonists occupy a patch or locality than in the absence of spatial context dependence.2.Previous work on contagion/compression focused primarily on the role of predators in driving colonization patterns. Our goal was to determine whether resource abundance can drive multiscale colonization dynamics of aquatic beetles through the processes of contagion and compression in naturally-colonized experimental pools.3.We established two levels (high/low quality) of within-patch resource abundances (leaf litter) using an experimental landscape of mesocosms, and assayed colonization by 35 species of aquatic beetles. Patches were arranged in localities (sets of two patches), which consisted of a combination of two patch-level resource levels in a 2 × 2 factorial design, allowing us to assay colonization at both locality and patch levels.4.We demonstrate that patterns of species abundance and richness of colonizing aquatic beetles are determined by patch quality and context-dependent processes at multiple spatial scales. Localities that consisted of at least one high quality patch were colonized at equivalent rates that were higher than localities containing only low quality patches, displaying regional reward contagion. In localities that consisted of one high and one low quality patch, reward contagion produced by higher leaf litter levels resulted in greater abundance of beetles in such localities, which then compressed into the highest quality patches.5.Our results provide further support for the critical roles of habitat selection and spatial context, particularly the quality of neighboring habitat patches, in generating patterns of species abundances and community structure across landscapes.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.
  • Resource stoichiometry and availability modulate species richness and
           biomass of tropical litter macro-invertebrates
    • Abstract: 1. The high biodiversity and biomass of soil communities is crucial for litter decomposition in terrestrial ecosystems such as tropical forests. However, the leaf litter that these communities consume is of particularly poor quality as indicated by elemental stoichiometry. The impact of resource quantity, quality, and other habitat parameters on species richness and biomass of consumer communities is often studied in isolation, although much can be learned from simultaneously studying both community characteristics.2. Using a data set of 780 macro-invertebrate consumer species across 32 sites in tropical lowland rainforest and agricultural systems on Sumatra, Indonesia, we investigated the effects of basal resource stoichiometry (C:X ratios of N, P, K, Ca, Mg, Na, S in local leaf litter), litter mass (basal resource quantity and habitat space), plant species richness (surrogate for litter habitat heterogeneity), and soil pH (acidity) on consumer species richness and biomass across different consumer groups (i.e., three feeding guilds and ten selected taxonomic groups).3. In order to distinguish the most important predictors of consumer species richness and biomass, we applied a standardised model averaging approach investigating the effects of basal resource stoichiometry, litter mass, plant species richness, and soil pH on both consumer community characteristics. This standardised approach enabled us to identify differences and similarities in the magnitude and importance of such effects on consumer species richness and biomass.4. Across consumer groups, we found litter mass to be the most important predictor of both species richness and biomass. Resource stoichiometry had a more pronounced impact on consumer species richness than on their biomass. As expected, taxonomic groups differed in which resource and habitat parameters (basal resource stoichiometry, litter mass, plant species richness, and pH) were most important for modulating their community characteristics.5. The importance of litter mass for both species richness and biomass indicates that these tropical consumers strongly depend on habitat space and resource availability. Our study supports previous theoretical work indicating that consumer species richness is jointly influenced by resource availability and the balanced supply of multiple chemical elements in their resources.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.
  • The role of rare morph advantage and conspicuousness in the stable
           gold-dark colour polymorphism of a crater lake Midas cichlid fish
    • Abstract: 1.Genetically based stable colour polymorphisms provide a unique opportunity to study the evolutionary processes that preserve genetic variability in the wild. Different mechanisms are proposed to promote the stability of polymorphisms, but only few empirical examples have been documented, resulting in an incomplete understanding of these mechanisms.2.A remarkable genetically-determined stable colour polymorphism is found in the Nicaraguan Midas cichlid species complex (Amphilophus cf. citrinellus). All Midas cichlids start their life with a dark-grey colouration (dark morph), but individuals carrying the dominant “gold” allele (~10%) lose their melanophores later in life, revealing the underlying orange colouration (gold morph). How this polymorphism is maintained remains unclear. Two main hypotheses have been proposed, both suggesting differential predation upon colour morphs as the proximate mechanism. One predicts that the conspicuous gold morph is more likely to be preyed upon, but this disadvantage is balanced by their competitive dominance over the dark morph. The second hypothesis suggests a rare morph advantage where the rarer gold morph experiences less predation. Empirical evidence for either of these mechanisms is still circumstantial and inconclusive.3.We conducted two field experiments in a Nicaraguan crater lake using wax models simulating both morphs to determine predation pressure upon Midas cichlid colour morphs. First, we tested the interaction of colouration and depth on attack rate. Second, we tested the interaction of fish size and colouration. We contrasted the pattern of attacks from these experiments to the predicted predation patterns from the hypotheses proposed to explain the colour polymorphism's stability.4.Large models imitating colour morphs were attacked at similar rates irrespectively of their position in the water column. Yet, attacks upon small models resembling juveniles were directed mainly toward dark models. This resulted in a significant size-by-colour interaction.5.We suggest that gold Midas cichlids experience a rare morph advantage as juveniles when individuals of this morph are extremely uncommon. But this effect is reduced or disappears among adults, where gold individuals are relatively more common. Thus, the interaction of rare morph advantage and conspicuousness, rather than either of those factors alone, is a likely mechanism resulting in the stability of the colour polymorphism in Midas cichlids.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.
  • Reproductive performance of resident and migrant males, females and pairs
           in a partially migratory bird
    • Abstract: 1.Quantifying among-individual variation in life-history strategies, and associated variation in reproductive performance and resulting demographic structure, is key to understanding and predicting population dynamics and life-history evolution. Partial migration, where populations comprise a mixture of resident and seasonally-migrant individuals, constitutes a dimension of life-history variation that could be associated with substantial variation in reproductive performance. However, such variation has rarely been quantified due to the challenge of measuring reproduction and migration across a sufficient number of seasonally-mobile males and females.2.We used intensive winter (non-breeding season) resightings of colour-ringed adult European shags (Phalacrocorax aristotelis) from a known breeding colony to identify resident and migrant individuals. We tested whether two aspects of annual reproductive performance, brood hatch date and breeding success, differed between resident and migrant males, females and breeding pairs observed across three consecutive winters and breeding seasons.3.The sex ratios of observed resident and migrant shags did not significantly differ from each other or from 1:1, suggesting that both sexes are partially migratory and that migration was not sex-biased across surveyed areas.4.Individual resident males and females hatched their broods 6 days earlier and fledged 0.2 more chicks per year than migrant males and females on average. Resident individuals of both sexes therefore had higher breeding success than migrants.5.Hatch date and breeding success also varied with a pair's joint migratory strategy such that resident-resident pairs hatched their broods 12 days earlier than migrant-migrant pairs, and fledged 0.7 more chicks per year on average. However, there was no evidence of assortative pairing with respect to migratory strategy: observed frequencies of migrant-migrant and resident-resident pairs did not differ from those expected given random pairing.6.These data demonstrate substantial variation in two key aspects of reproductive performance associated with the migratory strategies of males, females and breeding pairs within a partially migratory population. These patterns could reflect direct and/or indirect mechanisms, but imply that individual variation in migratory strategy, and variation in pairing among residents and migrants, could influence selection on migration and drive complex population and evolutionary dynamics.This article is protected by copyright. All rights reserved.
  • Conspecific and not performance-based attraction on immigrants drives
           colony growth in a waterbird
    • Abstract: SummaryLocal recruitment and immigration play an important part in the dynamics and growth of animal populations. However, their estimation and incorporation into open populations models is, in most cases, problematic. We studied factors affecting the growth of a recently established colony of Eurasian spoonbill (Platalea leucorodia) and assessed the contribution of local recruits, i.e. birds born in the colony, and immigrants, i.e. birds of unknown origin, to colony growth.We applied an integrated population model that accounts for uncertainty in breeding state assignment and merges population surveys, local fecundity and individual longitudinal data of breeding and non-breeding birds, to estimate demographic rates and the relative role of recruitment and immigration in driving the local dynamics. We also used this analytical framework to assess the degree of support for the ʻperformance-basedʼ and ʻconspecific attractionʼ hypotheses as possible mechanisms of colony growth.Among the demographic rates, only immigration was positively and significantly correlated with population growth rate. In addition, the number of immigrants settling in the colony was positively correlated with colony size in the previous and current year, but was not correlated with fecundity of the previous year.Our results suggest that the variation in immigration affected colony dynamics and that conspecific attraction likely triggered the relevant role of immigration in the growth of a recently formed waterbird colony, supporting the need of including immigration in population analysis.This article is protected by copyright. All rights reserved.
  • Individual versus pseudo-repeatability in behaviour: lessons from
           translocation experiments in a wild insect
    • Abstract: 1.Repeatability represents a key parameter in ecological and evolutionary research. Repeatability is underpinned by developmental plasticity and genetic variation but may become biased upwards by repeatable differences in environments to which individuals respond plastically. The extent of upward bias caused by the latter mechanism (causing “pseudo-repeatability”) is important yet rarely investigated in ecological research.2.We repeatedly assayed a key behaviour (flight initiation distance) affecting longevity in a wild cricket population (Gryllus campestris). We used naturally moving, translocated, and forced-stationary individuals to study bias in repeatability caused by spatial variability in environmental conditions.3.Our experiments acknowledged that translocations might themselves bias repeatability estimates if animals respond to handling procedures (a necessary component of translocations). Individuals were therefore either (i) repeatedly translocated and assayed, or (ii) assayed at multiple burrows as part of natural movements. This enabled estimation of behavioural variance attributable to individual, burrow, and residual components within each treatment; comparison across treatments addressed whether translocations caused bias. We also calculated repeatability for individuals that forced to be stationary to investigate whether this led to upward biases of repeatability.4.For adult crickets, individual explained 17.8% versus 17.2%, and burrow 8.7% versus 10.3%, of the behavioural variance in translocated versus natural-movement treatments. Repeatability for forced-stationary adults was 31.1%, thereby demonstrating experimentally that certain study designs bias repeatability upwards. For translocated juveniles, individual explained 10.0% and burrow 6.0% of the variance while in the natural-movement treatment those components could not be separated as juveniles do not switch burrows. Translocations did not lead to detectable biases in behavioural mean or variance.5.Repeatability was not biased for adults subjected to the natural-movement treatment because individuals were assayed under many different environments, facilitating the separation of individual from burrow effects. Upward bias would have occurred with less optimal sampling schemes: if individuals had been assayed repeatedly at the same burrow. We therefore recommend that translocation experiments are more commonly applied, particularly in stationary species, to ensure the unbiased estimation of repeatability.This article is protected by copyright. All rights reserved.
  • Time since disturbance affects colonization dynamics in a metapopulation
    • Abstract: 1.Disturbances are widespread in nature and can have substantial population-level consequences. Most empirical studies on the effects of disturbance track population recovery within habitat patches, but have an incomplete representation of the recolonization process. Additionally, recent metapopulation models represent post-disturbance colonization with a recovery state or time-lag for disturbed (“focal”) patches, thus assuming that recolonization rates are uniform.2.However, the availability of colonists in neighboring “source” patches can vary, especially in frequently-disturbed landscapes such as fire-managed forests that have a mosaic of patches that differ in successional state and undergo frequent local extinctions. To determine how time since disturbance in both focal and neighboring source patches might affect metapopulations, we studied the effects of time since fire (TSF) on abundances of a specialist palmetto beetle within and between fire management units in Apalachicola National Forest, Florida.3.We measured beetle abundances at three distances from the shared edge of paired units, with units ranging from 0-64 months since fire and the difference in time since burning for a focal-source pair ranging from 3-58 months.4.Soon after fire, beetle abundances within management units were highest near the unit edge, but this pattern changed with increasing TSF. Between paired units, the more recently-disturbed (“focal”) unit's beetle abundance was positively related to source unit abundance, but the shape of this relationship differed based on focal unit TSF and the units’ difference in time since burning.5.Results suggest that both focal and source habitat history can influence recolonization of recently-disturbed patches and that these effects may persist over years. Thus, when predicting metapopulation dynamics, variation in habitat characteristics should be considered not only for patches receiving colonists, but for patches supplying colonists as well.This article is protected by copyright. All rights reserved.
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