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ZOOLOGY (118 journals)                  1 2     

Acta Herpetologica     Open Access   (4 followers)
Acta Theriologica     Full-text available via subscription   (6 followers)
Acta Zoologica     Hybrid Journal   (3 followers)
Acta zoológica mexicana     Open Access  
African Invertebrates     Open Access  
African Journal of Herpetology     Full-text available via subscription   (1 follower)
African Zoology     Open Access   (6 followers)
animal     Hybrid Journal   (3 followers)
Animal Behaviour     Hybrid Journal   (127 followers)
Animal Biology     Full-text available via subscription   (8 followers)
Animal Biology & Animal Husbandry     Open Access   (5 followers)
Animal Biotelemetry     Open Access   (2 followers)
Animal Genetics     Hybrid Journal   (6 followers)
Animal Migration     Open Access  
Animal Studies Journal     Open Access   (4 followers)
Annales UMCS, Zootechnica     Open Access   (1 follower)
Annales Zoologici     Full-text available via subscription  
Annales Zoologici Fennici     Open Access  
Annals of Animal Science     Open Access   (1 follower)
Annual Review of Animal Biosciences     Full-text available via subscription   (4 followers)
Anthropozoologica     Full-text available via subscription   (3 followers)
Anthrozoos : A Multidisciplinary Journal of The Interactions of People & Animals     Full-text available via subscription   (3 followers)
Applied Animal Behaviour Science     Hybrid Journal   (10 followers)
Applied Entomology and Zoology     Partially Free   (3 followers)
Aquatic Mammals     Full-text available via subscription   (3 followers)
Aquatic Sciences     Hybrid Journal   (10 followers)
Asian Journal of Animal and Veterinary Advances     Open Access   (5 followers)
Australian Journal of Zoology     Hybrid Journal   (1 follower)
Bioacoustics : The International Journal of Animal Sound and its Recording     Partially Free   (2 followers)
Bird Conservation International     Hybrid Journal   (12 followers)
Bird Study     Full-text available via subscription   (10 followers)
Brazilian Journal of Veterinary Research and Animal Science     Open Access   (5 followers)
British Birds     Full-text available via subscription   (6 followers)
Bulletin of the Museum of Comparative Zoology     Full-text available via subscription   (2 followers)
Canadian Journal of Animal Science     Full-text available via subscription   (4 followers)
Canadian Journal of Zoology     Full-text available via subscription   (11 followers)
Contributions to Zoology     Open Access   (3 followers)
Der Zoologische Garten     Full-text available via subscription   (2 followers)
Ecology of Freshwater Fish     Hybrid Journal   (14 followers)
Edentata     Open Access  
European Journal of Taxonomy     Open Access   (1 follower)
Euscorpius     Open Access  
EvoDevo     Open Access   (1 follower)
Fieldiana Zoology     Full-text available via subscription   (2 followers)
Fish and Fisheries     Hybrid Journal   (25 followers)
Frontiers in Zoology     Open Access   (6 followers)
Graellsia     Open Access  
Hystrix, the Italian Journal of Mammalogy     Open Access  
i-Perception     Open Access   (3 followers)
Iheringia. Série Zoologia     Open Access  
In Vitro Cellular & Developmental Biology - Animal     Hybrid Journal   (1 follower)
Integrative Zoology     Hybrid Journal  
International Journal of Odonatology     Hybrid Journal   (1 follower)
International Journal of Zoological Research     Open Access   (2 followers)
International Journal of Zoology     Open Access   (2 followers)
International Zoo Yearbook     Hybrid Journal  
Invertebrate Reproduction & Development     Hybrid Journal   (2 followers)
ISRN Zoology     Open Access   (3 followers)
Italian Journal of Animal Science     Open Access   (2 followers)
Italian Journal of Zoology     Hybrid Journal   (2 followers)
Journal of Agrobiology     Open Access   (2 followers)
Journal of Animal Ecology     Hybrid Journal   (24 followers)
Journal of Animal Physiology and Animal Nutrition     Hybrid Journal   (3 followers)
Journal of Apicultural Science     Open Access  
Journal of Basic & Applied Zoology : Physiology     Open Access  
Journal of Experimental Zoology Part A: Ecological Genetics and Physiology     Hybrid Journal   (2 followers)
Journal of Experimental Zoology Part B : Molecular and Developmental Evolution     Hybrid Journal  
Journal of Freshwater Ecology     Hybrid Journal   (9 followers)
Journal of Insects     Open Access  
Journal of Venomous Animals and Toxins     Open Access   (3 followers)
Journal of Venomous Animals and Toxins including Tropical Diseases     Open Access  
Journal of Wildlife Management     Hybrid Journal   (22 followers)
Journal of Zoo and Aquarium Research     Open Access  
Journal of Zoological Systematics and Evolutionary Research     Hybrid Journal   (4 followers)
Journal of Zoology     Hybrid Journal   (9 followers)
Laboratory Animals     Hybrid Journal   (8 followers)
Mammalia     Full-text available via subscription   (6 followers)
Marine Ecology Progress Series MEPS     Full-text available via subscription   (6 followers)
Mastozoología Neotropical     Open Access  
Memorias de la Conferencia Interna en Medicina y Aprovechamiento de Fauna Silvestre, Exótica y no Convencional     Open Access  
Neotropical Primates     Open Access  
New Zealand Journal of Zoology     Hybrid Journal  
Papéis Avulsos de Zoologia     Open Access   (1 follower)
Parasite     Open Access   (5 followers)
Physiological and Biochemical Zoology     Full-text available via subscription   (5 followers)
Polish Journal of Entomology     Open Access   (2 followers)
Protist Genomics     Open Access  
Research in Zoology     Open Access   (1 follower)
Revista Brasileira de Zoologia     Open Access  
Revista de Biología Marina y Oceanografía     Open Access   (1 follower)
Revista de Zoologia     Open Access   (1 follower)
Revista del Museo Argentino de Ciencias Naturales     Open Access  
Russian Journal of Herpetology     Full-text available via subscription   (1 follower)
Scientific Journal of Animal Science     Open Access   (2 followers)
Scientific Journal of Zoology     Open Access   (2 followers)
SHILAP Revista de Lepidopterologia     Open Access   (2 followers)
Skeletal Muscle     Open Access   (1 follower)
Sri Lanka Journal of Aquatic Sciences     Open Access  
Travaux du Muséum National d’Histoire Naturelle “Grigore Antipa”     Open Access  
Tropical Zoology     Partially Free   (1 follower)

        1 2     

Journal of Animal Ecology    [26 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  [1594 journals]   [SJR: 2.606]   [H-I: 94]
  • Linking Body Mass And Group Dynamics In An Obligate Cooperative Breeder
    • Abstract: Social and environmental factors influence key life‐history processes and population dynamics by affecting fitness‐related phenotypic traits such as body mass. The role of body mass is particularly pronounced in cooperative breeders due to variation in social status and consequent variation in access to resources. Investigating the mechanisms underlying variation in body mass and its demographic consequences can help elucidate how social and environmental factors affect the dynamics of cooperatively breeding populations. In this study, we present an analysis of the effect of individual variation in body mass on the temporal dynamics of group size and structure of a cooperatively breeding mongoose, the Kalahari meerkat, Suricata suricatta. First, we investigate how body mass interacts with social (dominance status and number of helpers) and environmental (rainfall and season) factors to influence key life‐history processes (survival, growth, emigration and reproduction) in female meerkats. Next, using an individual‐based population model, we show that the models explicitly including individual variation in body mass predict group dynamics better than those ignoring this morphological trait. Body mass influences group dynamics mainly through its effects on helper emigration and dominant reproduction. Rainfall has a trait‐mediated, destabilizing effect on group dynamics, whereas number of helpers has a direct and stabilizing effect. Counteracting effects of number of helpers on different demographic rates, despite generating temporal fluctuations, stabilizes group dynamics in the long term. Our study demonstrates that social and environmental factors interact to produce individual variation in body mass and accounting for this variation helps to explain group dynamics in this cooperatively breeding population. This article is protected by copyright. All rights reserved.
  • Trait‐Mediated Functional Responses: Predator Behavioral Type
           Mediates Prey Consumption
    • Abstract: The predator functional response (i.e. per capita consumption rate as a function of prey density) is central to our understanding of predator‐prey population dynamics. This response is behavioral, depending on the rate of attack and time it takes to handle prey. Consistent behavioral differences between conspecific individuals, termed behavioral types, are a widespread feature of predator and prey population s but the effects of behavioral types on the functional response remain unexplored. We tested the effects of crab (Panopeus herbstii) behavioral type, specifically individual activity level, on the crab functional response to mussel (Brachidontes exustus) prey. We further tested whether the effects of activity level on the response are mediated by the presence of toadfish (Opsanus tau) predation threat in the form of waterborne chemical cues known to reduce crab activity level. The effects of crab activity level on the functional response were dependent on crab body size. Individual activity level increased the magnitude (i.e. slope and asymptote) of the type II functional response of small crabs, potentially through an increase in time spent foraging, but had no effect on the functional response of large crabs. Predation threat did not interact with activity level to influence mussel consumption, but independently reduced the slope of the type II functional response. Overall, this study demonstrates size‐specific effects of a behavioral type on a predator‐prey interaction, as well as a general pathway (modification of the functional response) by which the effects of individual behavioral types can scale up to influence predator‐prey population dynamics. This article is protected by copyright. All rights reserved.
  • Parasites and genetic diversity in an invasive bumble bee
    • Abstract: Biological invasions are facilitated by the global transportation of species and climate change. Given that invasions may cause ecological and economic damage and pose a major threat to biodiversity understanding the mechanisms behind invasion success is essential. Both the release of non‐native populations from natural enemies, such as parasites, and the genetic diversity of these populations may play key roles in their invasion success. We investigated the roles of parasite communities, through enemy release and parasite acquisition, and genetic diversity in the invasion success of the non‐native bumblebee, Bombus hypnorum, in the United Kingdom. The invasive B. hypnorum had higher parasite prevalence than most, or all native congeners for two high impact parasites, probably due to higher susceptibility and parasite acquisition. Consequently parasites had a higher impact on B. hypnorum queens’ survival and colony‐founding success than on native species. B. hypnorum also had lower functional genetic diversity at the sex‐determining locus than native species. Higher parasite prevalence and lower genetic diversity have not prevented the rapid invasion of the UK by B. hypnorum. These data may inform our understanding of similar invasions by commercial bumble bees around the world. This study suggests that concerns about parasite impacts on the small founding populations common to re‐introduction and translocation programs may be less important than currently believed. This article is protected by copyright. All rights reserved.
  • Exotic birds increase generalization and compensate for native bird
           decline in plant‐frugivore assemblages
    • Abstract: 1. Exotic species are thought to alter the structure of natural communities and disrupt ecosystem functioning through invasion. Nevertheless, exotic species may also provide ecological insurance when they contribute to maintain ecosystem functions after the decline of native species following anthropogenic disturbance. 2. Here, this hypothesis is tested with the assemblage of frugivorous birds and fleshy‐fruited plants of New Zealand, which has suffered strong historical declines in native birds while simultaneously gaining new frugivores introduced by European settlers. 3. We studied the plant‐frugivore assemblage from measures of fruit and bird abundances and fruit consumption in nine forest patches, and tested how this changed across a gradient of relative abundance of exotic birds. We then examined how each bird species’ role in the assemblage (the proportion of fruits and the number of plant species consumed) varied with their relative abundance, body size, and native/exotic status. 4. The more abundant and, to a lesser extent, larger birds species consumed a higher proportion of fruits from more plant species. Exotic birds consumed fruits less selectively and more proportionate to the local availability than did native species. Interaction networks in which exotic birds had a stronger role as frugivores had higher generalization, higher nestedness and higher redundancy of plants. 5. Exotic birds maintained frugivory when native birds became rarer, and diversified the local spectrum of frugivores for co‐occurring native plants. These effects seemed related to the fact that species abundances, rather than trait‐matching constraints, ultimately determined the patterns of interactions between birds and plants. By altering the structure of plant‐frugivore assemblages, exotic birds likely enhance the stability of the community‐wide seed dispersal in the face of continued anthropogenic impact. This article is protected by copyright. All rights reserved.
  • Density‐dependent intraspecific aggression regulates survival in
           northern Yellowstone wolves (Canis lupus)
    • Abstract: 1. Understanding the population dynamics of top predators is essential to assess their impact on ecosystems and to guide their management. Key to this understanding is identifying the mechanisms regulating vital rates. 2. Determining the influence of density on survival is necessary to understand the extent to which human‐caused mortality is compensatory or additive. In wolves (Canis lupus), empirical evidence for density‐dependent survival is lacking. Dispersal is considered the principal way in which wolves adjust their numbers to prey supply or compensate for human exploitation. However, studies to date have primarily focused on exploited wolf populations, in which density‐dependent mechanisms are likely weak due to artificially low wolf densities. 3. Using 13 years of data on 280 collared wolves in Yellowstone National Park, we assessed the effect of wolf density, prey abundance and population structure, as well as winter severity, on age‐specific survival in two areas (prey‐rich vs. prey‐poor) of the national park. We further analysed cause‐specific mortality and explored the factors driving intraspecific aggression in the prey‐rich northern area of the park. 4. Overall, survival rates decreased during the study. In northern Yellowstone, density‐dependence regulated adult survival through an increase in intraspecific aggression, independent of prey availability. In the interior of the park, adult survival was less variable and density‐independent, despite reduced prey availability. There was no effect of prey population structure in northern Yellowstone, nor of winter severity in either area. Survival was similar among yearlings and adults, but lower for adults older than 6 years. 5. Our results indicate that density‐dependent intraspecific aggression is a major driver of adult wolf survival in northern Yellowstone, suggesting intrinsic density‐dependent mechanisms have the potential to regulate wolf populations at high ungulate densities. When low prey availability or high removal rates maintain wolves at lower densities, limited inter‐pack interactions may prevent density‐dependent survival, consistent with our findings in the interior of the park. This article is protected by copyright. All rights reserved.
  • Cascading effects of predator–detritivore interactions depend on
           environmental context in a Tibetan alpine meadow
    • Abstract: Studies of grazing food webs show that species traits can interact with environmental factors to determine the strength of trophic cascades, but analogous context dependencies in detrital food webs remain poorly understood. In predator–detritivore–plant interaction chains, predators are expected to indirectly suppress plant biomass by reducing the density of plant‐facilitating detritivores. However, this outcome can be reversed where above‐ground predators drive burrowing detritivores to lower soil levels, strengthening their plant‐facilitating effects. Here, we show that these trait‐mediated indirect interactions further depend on environmental context in a Tibetan alpine meadow. In our study system, undulating topography generates higher (dry soil) patches interspersed with lower (wet soil) patches. Because the ability of detritivores to form deep burrows is likely to be limited by oxygen availability in low patches (wet soil), we hypothesized that (i) burrowing detritivores would undergo a vertical habitat shift, allowing them to more effectively avoid predation, in high – but not low – patches, and (ii) this shift would transmit positive effects of predators to plants in high patches by improving conditions in the lower soil layer. We tested these hypotheses using complementary field and glasshouse experiments examining whether the cascading effects of above‐ground predatory beetles (presence/absence) on the density and behaviour of tunnel‐forming detritivorous beetles, soil properties, and plant growth varied with patch type (low/high). Results revealed that predatory beetles did not reduce the density of detritivores in either patch type but had context‐dependent trait‐mediated effects, increasing the tunnelling depth of detritivores, improving soil conditions and ultimately increasing plant biomass in the high but not low patches. This study adds to an emerging predictive framework linking predators to plants in detritus food webs, demonstrating that these indirect interactions depend not just on the relative habitat domains of predators and prey, but also on environmental conditions that can predictably constrain the behavioural response of detritivores to predation risk. This paper makes an important step towards predictive ecology in a heterogeneous world by revealing the importance of the physical environment as a modifier of trait‐based species interactions.
  • Phylogenetically related and ecologically similar carnivores harbour
           similar parasite assemblages
    • Abstract: Most parasites infect multiple hosts, but what factors determine the range of hosts a given parasite can infect' Understanding the broad scale determinants of parasite distributions across host lineages is important for predicting pathogen emergence in new hosts and for estimating pathogen diversity in understudied host species. In this study, we used a new data set on 793 parasite species reported from free‐ranging populations of 64 carnivore species to examine the factors that influence parasite sharing between host species. Our results showed that parasites are more commonly shared between phylogenetically related host species pairs. Additionally, host species with higher similarity in biological traits and greater geographic range overlap were also more likely to share parasite species. Of three measures of phylogenetic relatedness considered here, the number divergence events that separated host species pairs most strongly influenced the likelihood of parasite sharing. We also showed that viruses and helminths tend to infect carnivore hosts within more restricted phylogenetic ranges than expected by chance. Overall, our results underscore the importance of host evolutionary history in determining parasite host range, even when simultaneously considering other factors such as host ecology and geographic distribution. The authors show that the number of divergence events between host species is essential for predicting parasite assemblage similarity. Further, using a measure of host phylogenetic clustering that is independent of the number of host species infected, they show that many parasites, including those considered to be broad generalists, have host ranges significantly clustered on the host phylogeny.
  • Individual‐based analyses reveal limited functional overlap in a
           coral reef fish community
    • Abstract: Detailed knowledge of a species’ functional niche is crucial for the study of ecological communities and processes. The extent of niche overlap, functional redundancy and functional complementarity is of particular importance if we are to understand ecosystem processes and their vulnerability to disturbances. Coral reefs are among the most threatened marine systems, and anthropogenic activity is changing the functional composition of reefs. The loss of herbivorous fishes is particularly concerning as the removal of algae is crucial for the growth and survival of corals. Yet, the foraging patterns of the various herbivorous fish species are poorly understood. Using a multidimensional framework, we present novel individual‐based analyses of species’ realized functional niches, which we apply to a herbivorous coral reef fish community. In calculating niche volumes for 21 species, based on their microhabitat utilization patterns during foraging, and computing functional overlaps, we provide a measurement of functional redundancy or complementarity. Complementarity is the inverse of redundancy and is defined as less than 50% overlap in niche volumes. The analyses reveal extensive complementarity with an average functional overlap of just 15·2%. Furthermore, the analyses divide herbivorous reef fishes into two broad groups. The first group (predominantly surgeonfishes and parrotfishes) comprises species feeding on exposed surfaces and predominantly open reef matrix or sandy substrata, resulting in small niche volumes and extensive complementarity. In contrast, the second group consists of species (predominantly rabbitfishes) that feed over a wider range of microhabitats, penetrating the reef matrix to exploit concealed surfaces of various substratum types. These species show high variation among individuals, leading to large niche volumes, more overlap and less complementarity. These results may have crucial consequences for our understanding of herbivorous processes on coral reefs, as algal removal appears to depend strongly on species‐specific microhabitat utilization patterns of herbivores. Furthermore, the results emphasize the capacity of the individual‐based analyses to reveal variation in the functional niches of species, even in high‐diversity systems such as coral reefs, demonstrating its potential applicability to other high‐diversity ecosystems. This paper describes a novel approach to disentangle functional diversity using species’ realized functional niches. Using a multidimensional framework, the authors calculate the niche overlap between species and reveal surprisingly little redundancy in a herbivorous reef fish community. These results may change our understanding of herbivorous processes on coral reefs.
  • Integrating comparative functional response experiments into global change
    • Abstract: (a) Direct feeding interactions between a higher predator (the three‐spined stickleback, Gasterosteus aculeatus), intermediate consumers (native Mysis salemaai and invasive Hemimysis anomala mysids), and a basal prey (the cladoceran, Daphnia magna). Photo credits: G. aculeatus and H. anomala by Stephen Potts, M. salemaai and D. magna obtained from Wikimedia Commons; (b) functional response of three native mysids (in blue) and three invasive mysids (in red); (c) functional response of three native mysids and one stickleback (in blue) and three invasive mysids and one stickleback (in red). Shaded areas are bootstrapped 95% confidence intervals. Adapted from Barrios‐O'Neill et al. (). In Focus: Barrios‐O'Neill, D., Dick, J.T.A., Emmerson, M.C., Ricciardi, A., MacIsaac, H.J., Alexander, M.E. & Bovy, H.C. (2014) Fortune favours the bold: a higher predator reduces the impact of a native but not an invasive intermediate predator. Journal of Animal Ecology, 83, 693–701. There is a growing appreciation for the importance of non‐consumptive effects in predator–prey interaction research, which can often outweigh the importance of direct feeding. Barrios‐O'Neill et al. () report a novel method to characterize such effects by comparing the functional response of native and introduced intermediate consumers in the presence and absence of a higher predator. The invader exhibited stronger direct feeding and was also more resistant to intimidation by the higher predator. This experimental framework may be incorporated into mainstream global change research, for example, to quantify the importance of non‐consumptive effects for the success or failure of biological invasions. The article focuses on the paper by Barrios‐O'Neill et al. (2014) and in doing so discusses the functional response and non‐trophic interaction literature in the context of biological invasions. It also provides a future framework for integrating laboratory experiments, field manipulations and modelling approaches in global change research.
  • Building integral projection models: a user's guide
    • Abstract: In order to understand how changes in individual performance (growth, survival or reproduction) influence population dynamics and evolution, ecologists are increasingly using parameterized mathematical models. For continuously structured populations, where some continuous measure of individual state influences growth, survival or reproduction, integral projection models (IPMs) are commonly used. We provide a detailed description of the steps involved in constructing an IPM, explaining how to: (i) translate your study system into an IPM; (ii) implement your IPM; and (iii) diagnose potential problems with your IPM. We emphasize how the study organism's life cycle, and the timing of censuses, together determine the structure of the IPM kernel and important aspects of the statistical analysis used to parameterize an IPM using data on marked individuals. An IPM based on population studies of Soay sheep is used to illustrate the complete process of constructing, implementing and evaluating an IPM fitted to sample data. We then look at very general approaches to parameterizing an IPM, using a wide range of statistical techniques (e.g. maximum likelihood methods, generalized additive models, nonparametric kernel density estimators). Methods for selecting models for parameterizing IPMs are briefly discussed. We conclude with key recommendations and a brief overview of applications that extend the basic model. The online Supporting Information provides commented R code for all our analyses. A detailed description of the steps involved in constructing an IPM, explaining how to: (i) translate your study system into an IPM; (ii) implement your IPM; and (iii) diagnose potential problems with your IPM. We emphasize how the study organism's life cycle, and the timing of censuses, together determine the structure of the IPM kernel and important aspects of the statistical analysis used to parameterise an IPM using data on marked individuals.
  • Mate finding, Allee effects, and selection for sex‐biased dispersal
    • Abstract: Although dispersal requires context‐dependent decision‐making in three distinct stages (emigration, transit, immigration), these decisions are commonly ignored in simple models of dispersal. For sexually reproducing organisms, mate availability is an important factor in dispersal decisions. Difficulty finding mates can lead to an Allee effect where population growth decreases at low densities. Surprisingly, theoretical studies on mate finding and on sex‐biased dispersal produce opposing predictions: in the former one sex is predicted to move less if the other sex evolves to search more, whereas in the latter mate‐finding difficulties can select for less sex bias in dispersal when mate finding occurs after dispersal. Here we develop a pair of models to examine the joint evolution of dispersal and settlement behaviour. Our first model resolves the apparent contradiction from the mate‐search and dispersal literatures. Our second model demonstrates that the relationship between mating system and sex‐biased dispersal is more complex than a simple contrast between resource‐defence monogamy and female‐defence polygyny. Our results highlight that a key factor is the timing of mating relative to dispersal (before, during, or after). We also show that although movement has the potential to alleviate a mate‐finding Allee effect, in some cases it can actually exacerbate the effect.
  • Effects of spatial structure of population size on the population dynamics
           of barnacles across their elevational range
    • Abstract: 1. Explanations for why population dynamics vary across the range of a species reflect two contrasting hypotheses: (1) temporal variability of populations is larger in the centre of the range compared to the margins because overcompensatory density dependence destabilizes population dynamics, and (2) population variability is larger near the margins, where populations are more susceptible to environmental fluctuations. In both of these hypotheses, positions within the range are assumed to affect population variability. 2. In contrast, the fact that population variability is often related to mean population size implies that the spatial structure of the population size within the range of a species may also be a useful predictor of the spatial variation of temporal variability of population size over the range of the species. 3. To explore how population temporal variability varies spatially and the underlying processes responsible for the spatial variation, we focused on the intertidal barnacle Chthamalus dalli and examined differences in its population dynamics along the tidal levels it inhabits. Changes in coverage of barnacle populations were monitored for 10.5 years at 25 plots spanning the elevational range of this species. Data were analysed by fitting a population dynamics model to estimate the effects of density‐dependent and density‐independent processes on population growth. We also examined the temporal mean‐variance relationship of population size with parameters estimated from the population dynamics model. 4. We found that the relative variability of populations tended to increase from the centre of the elevational range towards the margins because of an increase in the magnitude of stochastic fluctuations of growth rates. Thus, our results supported hypothesis (2). We also found that spatial variations in temporal population variability were well characterized by Taylor's power law, the relative population variability being inversely related to the mean population size. 5. Results suggest that understanding the population dynamics of a species over its range may be facilitated by taking the spatial structure of population size into account as well as by considering changes in population processes as a function of position within the range of the species. This article is protected by copyright. All rights reserved.
  • Dual‐fuels: intra‐annual variation in the relative importance
           of benthic and pelagic resources to maintenance, growth and reproduction
           in a generalist salmonid fish
    • Abstract: Ecological systems are often characterised as stable entities. However, basal productivity in most ecosystems varies between seasons, particularly in subarctic and polar areas, but how this variability affects higher trophic levels or entire food webs remains largely unknown, especially in high latitude regions. We undertook a year‐long study of benthic (macroinvertebrate) and pelagic (zooplankton) resource availability, along with short‐ (day/days: stomach content), medium‐ (month: liver δ13C and δ15N isotopes) and long‐term (season: muscle δ13C and δ15N isotopes) assessments of resource use by a generalist fish, the European whitefish. in a deep, oligotrophic, subarctic lake in northern Europe. Due to the long ice‐covered winter period, we expected to find general benthic reliance throughout the year, but also a seasonal importance of zooplankton to the diet, somatic growth and gonadal development of whitefish. Benthic and pelagic resource availability varied between seasons: peak littoral benthic macroinvertebrate density occurred in mid‐winter, whereas maximum zooplankton density was observed in summer. Whitefish stomach content revealed a reliance on benthic prey items during winter and pelagic prey in summer. A seasonal shift from benthic to pelagic prey was evident in liver isotope ratios, but muscle isotope ratios indicated a year‐round reliance on benthic macroinvertebrates. Whitefish activity levels as well as somatic and gonadal growth all peaked during the summer, coinciding with the zooplankton peak and the warmest water temperature. Stable isotopes of muscle consistently depicted the most important resource, benthic macroinvertebrates, whereas short‐term indicators, i.e. diet and stable isotopes of liver, revealed the seasonal significance of pelagic zooplankton for somatic growth and gonad development. Seasonal variability in resource availability strongly influences consumer growth and reproduction and may also be important in other ecosystems facing pronounced annual weather fluctuations. This article is protected by copyright. All rights reserved.
  • Determination of temperate bird–flower interactions as entangled
           mutualistic and antagonistic sub‐networks: characterization at the
           network and species levels
    • Abstract: Most network studies on biological interactions consider only a single interaction type. However, individual species are simultaneously positioned in various types of interactions. The ways in which different network types are merged and entangled, and the variations in network structures between different sympatric networks, require full elucidation. Incorporating interaction types and disentangling complex networks is crucial, because the integration of various network architectures has the potential to alter the stability and co‐evolutionary dynamics of the whole network. To reveal how different types of interaction networks are entangled, we focused on the interaction between birds and flowers of temperate plants in Japan, where flower‐feeding birds are mainly generalist passerines, acting as pollinators and predators of flowers. Using long‐term monitoring data, we investigated the flower‐feeding episodes of birds. We constructed the whole network (WN) between birds and plants, separating the network into mutualistic and antagonistic sub‐networks (MS and AS, respectively). We investigated structural properties of the three quantified networks and species‐level characteristics of the main bird species. For bird species, we evaluated dietary similarity, dietary specialization and shifts of feeding behaviour relative to plant traits. Our results indicate that WN comprises entangled MS and AS, sharing considerable proportions of bird and plant assemblages. We observed distinctive differences in the network structural properties between the two sub‐networks. In comparison with AS, MS had lower numbers of bird and plant species, showed lower specialization and modularity and exhibited higher nestedness. At the species level, the Japanese white‐eye acted as pollinator, while the brown‐eared bulbul acted as both pollinator and predator for large numbers of flowers, based on its behavioural plasticity. Overall, the pattern of avian feeding behaviour was influenced by flower size and plant origin. Birds showed nectarivory for plants with medium‐sized flowers and exotic origins. Our results highlight the complex patterns of interactions between birds and the flowers of plants in temperate regions. They also indicate that understanding the interaction type for each species pair and consideration of the behavioural plasticity of animal species are important for elucidating integrated network structures. The authors demonstrate that the whole bird–flower network comprises entangled mutualistic and antagonistic sub‐networks, sharing considerable proportions of bird and plant assemblages, and these sub‐networks differ in their structural properties. Understanding the interaction type and considering the behavioural plasticity of animals are of great importance for elucidating integrated network structures.
  • Specialization and phenological synchrony of plant–pollinator
           interactions along an altitudinal gradient
    • Abstract: One of the most noticeable effects of anthropogenic climate change is the shift in timing of seasonal events towards earlier occurrence. The high degree of variation in species' phenological shifts has raised concerns about the temporal decoupling of interspecific interactions, but the extent and implications of this effect are largely unknown. In the case of plant–pollinator systems, more specialized species are predicted to be particularly threatened by phenological decoupling, since they are assumed to be less flexible in the choice of interaction partners, but until now this hypothesis has not been tested. In this paper, we studied phenology and interactions of plant and pollinator communities along an altitudinal gradient in the Alps as a model for the possible effects of climate change in time. Our results show that even relatively specialized pollinators were much more flexible in their use of plant species as floral resources than their local flower visitation suggested. We found no relationship between local specialization of pollinators and the consistency of their visitation patterns across sites, and also no relationship between specialization and phenological synchrony of pollinators with particular plants. Thus, in contrast to the conclusions of a recent simulation study, our results suggest that most pollinator species included in this study are not threatened by phenological decoupling from specific flowering plants. However, the flexibility of many rarely observed pollinator species remains unknown. Moreover, our results suggest that specialized flower visitors select plant species based on certain floral traits such as the length of the nectar holder tube. If that is the case, the observed flexibility of plant–pollinator interactions likely depends on a high degree of functional redundancy in the plant community, which may not exist in less diverse systems. Contrary to the results of a recent simulation study, this article shows that even relatively specialized pollinators are flexible in their choice of flowering plants and do not depend on phenological synchrony with particular plant species as floral resources. These results are highly relevant in the context of climate change.
  • A test for community saturation along the Himalayan bird diversity
           gradient, based on within‐species geographical variation
    • Abstract: The idea that ecological communities are unsaturated is central to many explanations for regional gradients in species diversity. We describe a test for differing degrees of saturation across a regional diversity gradient, based on within‐species geographical variation in ecological attributes. If communities in species‐poor regions are less saturated than communities in species‐rich regions, species that straddle both regions should have broader niches in species‐poor regions, exploiting resources that are consumed by other species in species‐rich regions. We studied 10 species of Old World leaf warblers that range across the Himalayas. Elevational range and feeding method showed niche contractions in the species‐poor north‐west Himalayas with respect to the species‐rich south‐east Himalayas, whereas prey size did not vary geographically. Niche contractions are contrary to the expectation of character release in depauperate environments, as has been shown, for example in mainland‐island comparisons. We show that arthropod abundances are likely a limiting resource, and that niche contractions are consistent with measurements of a narrowing of resource availability. Results suggest that north‐western warbler communities are at least as saturated as the south‐east and that lower resource diversity drives reduced species numbers. The idea that ecological communities are unsaturated is central to many explanations for latitudinal gradients in species diversity. This study devises a novel approach to test for community saturation. The authors show how patterns of within‐species geographical variation make a clear, testable prediction with respect to community saturation.
  • Does reduced mobility through fragmented landscapes explain patch
           extinction patterns for three honeyeaters'
    • Abstract: Habitat loss and associated fragmentation are major drivers of biodiversity decline, and understanding how they affect population processes (e.g. dispersal) is an important conservation goal. In a large‐scale test employing 10 × 10 km units of replication, three species of Australian birds, the fuscous honeyeater, yellow‐tufted honeyeater and white‐plumed honeyeater, responded differently to fragmentation. The fuscous and yellow‐tufted honeyeaters are ‘decliners’ that disappeared from suitable habitat in landscapes where levels of tree‐cover fell below critical thresholds of 17 and 8%, respectively. The white‐plumed honeyeater is a ‘tolerant’ species whose likelihood of occurrence in suitable habitat was independent of landscape‐level tree‐cover. To determine whether the absence of the two decliner species in low tree‐cover landscapes can be explained by reduced genetic connectivity, we looked for signatures of reduced mobility and gene flow in response to fragmentation across agricultural landscapes in the Box‐Ironbark region of north‐central Victoria, Australia. We compared patterns of genetic diversity and population structure at the regional scale and across twelve 100 km2 landscapes with different tree‐cover extents. We used genetic data to test landscape models predicting reduced dispersal through the agricultural matrix. We tested for evidence of sex‐biased dispersal and sex‐specific responses to fragmentation. Reduced connectivity may have contributed to the disappearance of the yellow‐tufted honey‐eater from low tree‐cover landscapes, as evidenced by male bias and increased relatedness among males in low tree‐cover landscapes and signals of reduced gene flow and mobility through the agricultural matrix. We found no evidence for negative effects of fragmentation on gene flow in the other decliner, the fuscous honeyeater, suggesting that undetected pressures act on this species. As expected, there was no evidence for decreased movement through fragmented landscapes for the tolerant white‐plumed honeyeater. We demonstrated effects of habitat loss and fragmentation (stronger patterns of genetic differentiation, increased relatedness among males) on the yellow‐tufted honeyeater above the threshold at which probability of occurrence dropped. Increasing extent and structural connectivity of habitat should be an appropriate management action for this species and other relatively sedentary woodland specialist species for which it can be taken as representative. The integration of molecular approaches, a multiple‐species framework and a replicated landscape‐scale study design, unusual in its extent, allowed for rigorous examination of the effects of habitat fragmentation on honeyeater population processes (e.g. mobility and gene flow) – not just patterns – at different temporal and spatial scales.
  • Changes in predator community structure shifts the efficacy of two warning
           signals in Arctiid moths
    • Abstract: Polymorphism in warning coloration is puzzling because positive frequency‐dependent selection by predators is expected to promote monomorphic warning signals in defended prey. We studied predation on the warning‐coloured wood tiger moth (Parasemia plantaginis) by using artificial prey resembling white and yellow male colour morphs in five separate populations with different naturally occurring morph frequencies. We tested whether predation favours one of the colour morphs over the other and whether that is influenced either by local, natural colour morph frequencies or predator community composition. We found that yellow specimens were attacked less than white ones regardless of the local frequency of the morphs indicating frequency‐independent selection, but predation did depend on predator community composition: yellows suffered less attacks when Paridae were abundant, whereas whites suffered less attacks when Prunellidae were abundant. Our results suggest that spatial heterogeneity in predator community composition can generate a geographical mosaic of selection facilitating the evolution of polymorphic warning signals. This is the first time this mechanism gains experimental support. Altogether, this study sheds light on the evolution of adaptive coloration in heterogeneous environments. This study provides the first experimental evidence that varying predator community composition can create mosaic selection for warning signals promoting colour polymorphism. This is an important step because data on which mechanisms really affect warning signal evolution in the wild are rare making findings of this work timely ones.
  • Heterochrony in a complex world: disentangling environmental processes of
           facultative paedomorphosis in an amphibian
    • Abstract: Heterochrony, the change in the rate or timing of development between ancestors and their descendants, plays a major role in evolution. When heterochrony produces polymorphisms, it offers the possibility to test hypotheses that could explain its success across environments. Amphibians are particularly suitable to exploring these questions because they express complex life cycles (i.e. metamorphosis) that have been disrupted by heterochronic processes (paedomorphosis: retention of larval traits in adults). The large phenotypic variation across populations suggests that more complex processes than expected are operating, but they remain to be investigated through multivariate analyses over a large range of natural populations across time. In this study, we compared the likelihood of multiple potential environmental determinants of heterochrony. We gathered data on the proportion of paedomorphic and metamorphic palmate newts (Lissotriton helveticus) across more than 150 populations during 10 years and used an information‐theoretic approach to compare the support of multiple potential processes. Six environmental processes jointly explained the proportion of paedomorphs in populations: predation, water availability, dispersal limitation, aquatic breathing, terrestrial habitat suitability and antipredator refuges. Analyses of variation across space and time supported models based on the advantage of paedomorphosis in favourable aquatic habitats. Paedomorphs were favoured in deep ponds, in conditions favourable to aquatic breathing (high oxygen content), with lack of fish and surrounded by suitable terrestrial habitat. Metamorphs were favoured by banks allowing easy dispersal. These results indicate that heterochrony relies on complex processes involving multiple ecological variables and exemplifies why heterochronic patterns occur in contrasted environments. On the other hand, the fast selection of alternative morphs shows that metamorphosis and paedomorphosis developmental modes could be easily disrupted in natural populations. This study indicates that heterochrony relies on more complex processes involving multiple ecological variables than usually thought. This exemplifies why heterochronic patterns occur in contrasted environments. On the other hand, the fast selection of alternative morphs shows that metamorphosis and paedomorphosis developmental modes could be easily disrupted in natural populations.
  • Pollen mixing in pollen generalist solitary bees: a possible strategy to
           complement or mitigate unfavourable pollen properties'
    • Abstract: Generalist herbivorous insects, which feed on plant tissue that is nutritionally heterogeneous or varies in its content of secondary metabolites, often benefit from dietary mixing through more balanced nutrient intake or reduced exposure to harmful secondary metabolites. Pollen is similarly heterogeneous as other plant tissue in its content of primary and secondary metabolites, suggesting that providing their offspring with mixed pollen diets might be a promising strategy for pollen generalist bees to complement nutrient imbalances or to mitigate harmful secondary metabolites of unfavourable pollen. In the present study, we compared larval performance of the pollen generalist solitary bee species Osmia cornuta (Megachilidae) on five experimental pollen diets that consisted of different proportions of unfavourable pollen diet of Ranunculus acris (Ranunculaceae) and favourable pollen diet of Sinapis arvensis (Brassicaceae). In addition, we microscopically analysed the pollen contained in the scopal brushes of field‐collected females of O. cornuta and three closely related species to elucidate to what degree these pollen generalist bees mix pollen of different hosts in their brood cells. In striking contrast to a pure Ranunculus pollen diet, which had a lethal effect on most developing larvae of O. cornuta, larval survival, larval development time and adult body mass of both males and females remained nearly unaffected by the admixture of up to 50% of Ranunculus pollen diet to the larval food. Between 42% and 66% of all female scopal pollen loads analysed contained mixtures of pollen from two to six plant families, indicating that pollen mixing is a common behaviour in O. cornuta and the three related bee species. The present study provides the first evidence that the larvae of pollen generalist bees can benefit from the nutrient content of unfavourable pollen without being negatively affected by its unfavourable chemical properties if such pollen is mixed with favourable pollen. We conclude that the widespread pollen mixing by females of pollen generalist bees should also be considered as a possible strategy to exploit flowers with unfavourable pollen and to optimize larval food quality. The larvae of a solitary bee species can benefit from the nutrient content of unfavourable pollen if such pollen is mixed with favourable pollen in their diet. Thus, pollen mixing in pollen generalist bees should also be considered as a possible strategy to exploit flowers with unfavourable pollen.
  • An experimental test of host specialization in a ubiquitous polar
           ectoparasite: a role for adaptation'
    • Abstract: The evolution of host specificity is considered to be an essential mechanism driving parasite diversity. It may be governed by adaptive constraints that lead to host‐dependent fitness trade‐offs. Alternatively, specificity may arise via transmission constraints that isolate parasite populations, without necessarily involving adaptation per se. Here, we ask whether the repeated observation of host‐associated genetic races across the worldwide distribution of the seabird ectoparasite Ixodes uriae is associated with host adaptation. We conducted a field‐based experiment to test for adaptive specialisation in host races of I. uriae. We transferred unengorged ticks of two life stages (nymphs and adults) originating from three host species (black‐legged kittiwake, common guillemot and Atlantic puffin) onto young kittiwake nestlings and followed attraction and attachment rates, engorgement times and feeding success of the transplanted ticks. All ticks were also typed genetically to match exploitation patterns with genetic differences among races. Ticks from atypical hosts were significantly less attracted to nestlings than ticks from the typical host, and showed lower feeding success and higher mortality. The degree of host specificity matched patterns of neutral genetic variation among races, with puffin ticks being more specific than guillemot ticks. Differences in specificity were also apparent among tick life stages, suggesting that nymphal ticks may be less discriminating of host type than adult ticks. Our results indicate that the genetic divergence previously observed among sympatric I. uriae host races is at least partially linked to adaptive specialisation to the host species and not simply to host‐mediated transmission. They also suggest that the adaptation process may evolve differently in different life stages based on trade‐offs with physiological constraints. The identification of the selective forces acting in host specialization will now be necessary to better characterize these patterns and to understand how transmission interacts with the adaptation process to generate parasite biodiversity. This study describes a rare and important transplantation experiment highlighting the role of host adaptation in parasite diversification.
  • Linking manipulative experiments to field data to test the dilution effect
    • Abstract: The dilution effect, the hypothesis that biodiversity reduces disease risk, has received support in many systems. However, few dilution effect studies have linked mechanistic experiments to field patterns to establish both causality and ecological relevance. We conducted a series of laboratory experiments and tested the dilution effect hypothesis in an amphibian‐Batrachochytrium dendrobatidis (Bd) system and tested for consistency between our laboratory experiments and field patterns of amphibian species richness, host identity and Bd prevalence. In our laboratory experiments, we show that tadpoles can filter feed Bd zoospores and that the degree of suspension feeding was positively associated with their dilution potential. The obligate suspension feeder, Gastrophryne carolinensis, generally diluted the risk of chytridiomycosis for tadpoles of Bufo terrestris and Hyla cinerea, whereas tadpoles of B. terrestris (an obligate benthos feeder) generally amplified infections for the other species. In addition, G. carolinensis reduced Bd abundance on H. cinerea more so in the presence than absence of B. terrestris and B. terrestris amplified Bd abundance on H. cinerea more so in the absence than presence of G. carolinensis. Also, when ignoring species identity, species richness was a significant negative predictor of Bd abundance. In our analysis of field data, the presence of Bufo spp. and Gastrophryne spp. were significant positive and negative predictors of Bd prevalence, respectively, even after controlling for climate, vegetation, anthropogenic factors (human footprint), species richness and sampling effort. These patterns of dilution and amplification supported our laboratory findings, demonstrating that the results are likely ecologically relevant. The results from our laboratory and field data support the dilution effect hypothesis and also suggest that dilution and amplification are predictable based on host traits. Our study is among the first to link manipulative experiments, in which a potential dilution mechanism is supported, with analyses of field data on species richness, host identity, spatial autocorrelation and disease prevalence. This study of the dilution effect is among the first to link manipulative experiments, in which a potential dilution mechanism is supported, with analyses of field data on species richness, host identity, spatial autocorrelation and disease prevalence.
  • Subtype diversity and reassortment potential for co‐circulating
           avian influenza viruses at a diversity hot spot
    • Abstract: Biological diversity has long been used to measure ecological health. While evidence exists from many ecosystems that declines in host biodiversity may lead to greater risk of disease emergence, the role of pathogen diversity in the emergence process remains poorly understood. Particularly, because a more diverse pool of pathogen types provides more ways in which evolutionary innovations may arise, we suggest that host–pathogen systems with high pathogen diversity are more prone to disease emergence than systems with relatively homogeneous pathogen communities. We call this prediction the diversity‐emergence hypothesis. To show how this hypothesis could be tested, we studied a system comprised of North American shorebirds and their associated low‐pathogenicity avian influenza (LPAI) viruses. These viruses are important as a potential source of genetic innovations in influenza. A theoretical contribution of this study is an expression predicting the rate of viral subtype reassortment to be proportional to both prevalence and Simpson's Index, a formula that has been used traditionally to quantify biodiversity. We then estimated prevalence and subtype diversity in host species at Delaware Bay, a North American AIV hotspot, and used our model to extrapolate from these data. We estimated that 4 to 39 virus subtypes circulated at Delaware Bay each year between 2000 and 2008, and that surveillance coverage (percentage of co‐circulating subtypes collected) at Delaware Bay is only about 63·0%. Simpson's Index in the same period varied more than fourfold from 0·22 to 0·93. These measurements together with the model provide an indirect, model‐based estimate of the reassortment rate. A proper test of the diversity‐emergence hypothesis would require these results to be joined to independent and reliable estimates of reassortment, perhaps obtained through molecular surveillance. These results suggest both that subtype diversity (and therefore reassortment) varies from year to year and that several subtypes contributing to reassortment are going undetected. The similarity between these results and more detailed studies of one host, ruddy turnstone (Arenaria interpres), further suggests that this species may be the primary host for influenza reassortment at Delaware Bay. Biological diversity has long been quantified using Simpson's Index. Our model links this formula to a mechanistic account of reassortment in multipathogen systems in the form of subtype diversity at Delaware Bay, USA. As a theory of how pathogen diversity may influence the evolution of novel pathogens, this work is a contribution to the larger project of understanding the connections between biodiversity and disease. This study provides the first mechanistic description of how diversity affects evolution in a host–pathogen system with a mathematical model that shows the relationship between diversity and reassortment. Pathogen evolution is critical to understanding emerging infectious diseases, and these findings are relevant to understanding emergence in many zoonotic pathogens.
  • Individual‐based measurements of light intensity provide new
           insights into the effects of artificial light at night on daily rhythms of
           urban‐dwelling songbirds
    • Abstract: The growing interest in the effects of light pollution on daily and seasonal cycles of animals has led to a boost of research in recent years. In birds, it has been hypothesized that artificial light at night can affect daily aspects of behaviour, but one caveat is the lack of knowledge about the light intensity that wild animals, such as birds, are exposed to during the night. Organisms have naturally evolved daily rhythms to adapt to the 24‐h cycle of day and night, thus, it is important to investigate the potential shifts in daily cycles due to global anthropogenic processes such as urbanization. We captured adult male European blackbirds (Turdus merula) in one rural forest and two urban sites differing in the degree of anthropogenic disturbance. We tagged these birds with light loggers and simultaneously recorded changes in activity status (active/non‐active) through an automated telemetry system. We first analysed the relationship between light at night, weather conditions and date with daily activity onset and end. We then compared activity, light at night exposure and noise levels between weekdays and weekends. Onset of daily activity was significantly advanced in both urban sites compared to the rural population, while end of daily activity did not vary either among sites. Birds exposed to higher amounts of light in the late night showed earlier onset of activity in the morning, but light at night did not influence end of daily activity. Light exposure at night and onset/end of daily activity timing was not different between weekdays and weekends, but all noise variables were. A strong seasonal effect was detected in both urban and rural populations, such as birds tended to be active earlier in the morning and later in the evening (relative to civil twilight) in the early breeding season than at later stages. Our results point at artificial light at night as a major driver of change in timing of daily activity. Future research should focus on the costs and benefits of altered daily rhythmicity in birds thriving in urban areas. Using miniature light‐loggers, the authors measure the light intensity to which free‐ranging urban and rural European blackbirds are exposed to at night. In addition, they correlate these measurements to the onset and offset of activity of each individual bird, recorded via automatic radio‐telemetry.
  • Fortune favours the bold: a higher predator reduces the impact of a native
           but not an invasive intermediate predator
    • Abstract: Emergent multiple predator effects (MPEs) might radically alter predictions of predatory impact that are based solely on the impact of individuals. In the context of biological invasions, determining if and how the individual‐level impacts of invasive predators relates to their impacts in multiple‐individual situations will inform understanding of how such impacts might propagate through recipient communities. Here, we use functional responses (the relationship between prey consumption rate and prey density) to compare the impacts of the invasive freshwater mysid crustacean Hemimysis anomala with a native counterpart Mysis salemaai when feeding on basal cladoceran prey (i) as individuals, (ii) in conspecific groups and (iii) in conspecific groups in the presence of a higher fish predator, Gasterosteus aculeatus. In the absence of the higher predator, the invader consumed significantly more basal prey than the native, and consumption was additive for both mysid species – that is, group consumption was predictable from individual‐level consumption. Invaders and natives were themselves equally susceptible to predation when feeding with the higher fish predator, but an MPE occurred only between the natives and higher predator, where consumption of basal prey was significantly reduced. In contrast, consumption by the invaders and higher predator remained additive. The presence of a higher predator serves to exacerbate the existing difference in individual‐level consumption between invasive and native mysids. We attribute the mechanism responsible for the MPE associated with the native to a trait‐mediated indirect interaction, and further suggest that the relative indifference to predator threat on the part of the invader contributes to its success and impacts within invaded communities. This study demonstrates how the individual‐level impacts of native and invasive predators translate to impacts in multi‐predator contexts. The authors use a functional response‐based approach to highlight the density‐dependence of emergent effects, and show how the presence of a higher predator exacerbates the difference between the impacts of natives and invaders.
  • Divergence in threat sensitivity among aquatic larvae of cryptic mosquito
    • Abstract: Predation is a major evolutionary force driving speciation. The threat‐sensitive response hypothesis predicts that prey adjust and balance the time spent on a costly antipredator response with other activities that enhance their fitness. Thus, prey able to develop an antipredator response proportional to risk intensity should have a selective advantage. Knowledge on how evolution has shaped threat sensitivity among closely related species exposed to different predation pressures is scarce, prompting investigations to better predict and explain its effect on communities. We explored and compared the antipredator response of aquatic mosquito larvae in three sibling species of the Anopheles gambiae complex, with contrasting larval biologies in Burkina Faso. Anopheles arabiensis and An. gambiae sensu stricto breed in temporary water collections where predator densities are low, whereas Anopheles coluzzii is able to thrive in permanent pools where the predation pressure is much higher. We hypothesized that the increase and decline of behavioural antipredator responses might differ between the three species over time. To test this hypothesis, progenies of field‐collected mosquitoes were experimentally exposed to a range of soluble predation cues and their response was monitored for up to 48 h. The three species were all threat sensitive but their reaction norms differed. For the range of concentrations tested, An. coluzzii larvae gradually increased in antipredator response, whereas An. gambiae larvae readily displayed antipredator behaviour at low concentrations leading to a saturation of the response for high cue concentrations. An. arabiensis displayed a narrower reaction norm with low response intensity. Larval instars did not differ in their threat sensitivity. The antipredator behaviour of the three species waned after about 1 h of exposure. Early instars tended to express antipredation behaviour for longer than did older instars. This study provides information on how aquatic prey species with an aerial adult stage manage larval predation risk over time according to cue concentrations and suggests that different predation pressures might play a role as a disruptive selective force fostering habitat segregation and speciation within the An. gambiae complex. The evolution of phenotypic plasticity is further discussed in the light of divergent predation pressures. Within the frameworks of ecological speciation and predation pressure, this study is the first of its kind to target subtle differences between incipient species, therefore placing this work at a new taxonomic level and at a decisive time in species diversification.
  • Lasting effects of snow accumulation on summer performance of large
           herbivores in alpine ecosystems may not last
    • Abstract: One of the clearest predictions from the IPCC is that we can expect much less snow cover due to global warming in the 21st century, especially in the lower alpine areas. In alpine ecosystems, snow accumulation in depressions gives rise to distinct snow‐bed vegetation types, assumed to play a key role in ecosystem function. A delayed plant phenology yields high‐quality forage in late summer for wild and domestic herbivores. Yet, the mechanistic pathways for how declining snow may affect future performance of large herbivores beyond the effect of phenology remain poorly documented. Here, we link unique individual‐based data on diet choice, habitat selection and performance of domestic sheep over a 10‐year period to manually GPS‐recorded spatial positions of snow cover in early summer (0·57% to 43·3% in snow beds on 1st of July) in an alpine ecosystem. Snowy winters gave a higher proportion of easily digestible herbs in the diet and a more variable use of snow‐bed and meadow vegetation types resulting in faster growing lambs. These patterns were consistent between two density treatment levels although slightly more marked for diet at low density, suggesting that effects of simple mitigation efforts such as managing population numbers will be meagre. Our study thus yields novel insight into the strong impact of melting snow on ecosystem function in alpine habitats, which are likely to affect productivity of both domestic and wild ungulate populations. One of the clearest predictions from the IPCC is that we can expect much less snow cover due to global warming in the 21st century. Here, the authors provide a new mechanistic pathway for how declining snow may affect future performance of large herbivores beyond the effect of plant phenology.
  • Pulsed resources and the coupling between life‐history strategies
           and exploration patterns in eastern chipmunks (Tamias striatus)
    • Abstract: Understanding the causes of animal personality (i.e. consistent behavioural differences) is a major aim of evolutionary studies. Recent theoretical work suggests that major personality traits may contribute to evolutionary trade‐offs. However, such associations have only been investigated in a few study systems, and even less so in free ranging animal populations. Eastern chipmunks exhibit consistent individual differences in exploration, ranging from slow to fast. Birth cohorts also experience dramatic differences in age at first breeding opportunity due to annual differences in beech mast. Individuals may breed for the first time at 24, 33 or 50% of their average life span, depending on year of birth. Here, we used data from a long‐term survey on a wild population to investigate the relationship between reproductive life history and consistent individual differences in exploration. We determined whether predictable differences in age at first breeding opportunity among birth cohorts were associated with exploration differences and favoured individuals with different exploration. Birth cohorts with a predictably earlier age at first breeding opportunity were faster explorers on average. Slower explorers displayed their highest fecundity (females) or highest fertilization success (males) later in their life compared with faster explorers. Overall, slow explorers attained a higher lifetime reproductive success than fast explorers when given an opportunity to reproduce later in their life. Our results suggest that the timing of mating seasons, associated with fluctuating food abundance, may favour individual variation in exploration and maintain population variation through its effects on reproductive life history. Together, our result shed light on how fluctuation in ecological conditions may maintain personality differences and on the nature of the relationships between animal personality and life history. The authors report how individual exploration predicts age at first reproduction and reproductive life history in a population of eastern chipmunks. They also show that pulsed fluctuations in food abundance, associated with beech mast, may maintain individual differences in exploration in this population. Picture credit: C. Couchoux
  • Changes in breeding phenology and population size of birds
    • Abstract: Although the phenology of numerous organisms has advanced significantly in response to recent climate change, the life‐history and population consequences of earlier reproduction remain poorly understood. We analysed extensive data on temporal change in laying date and clutch size of birds from Europe and North America to test whether these changes were related to recent trends in population size. Across studies, laying date advanced significantly, while clutch size did not change. However, within populations, changes in laying date and clutch size were positively correlated, implying that species which advanced their laying date the most were also those that increased their clutch size the most. Greater advances in laying date were associated with species that had multiple broods per season, lived in nonagricultural habitats and were herbivorous or predatory. The duration of the breeding season increased for multibrooded species and decreased for single‐brooded species. Changes in laying date and clutch size were not related to changes in population size (for resident or migratory species). This suggests that, across a wide variety of species, mismatches in the timing of egg laying or numbers of offspring have had relatively little influence on population size compared with other aspects of phenology and life history. Climate change is often associated with earlier breeding in birds, and this advancement could ultimately affect population size. The authors conduct a comparative analysis and find no connection between changes in laying date and recent trends in population size. They suggest factors other than mismatching may be influencing population trends.
  • Body size, carry‐over effects and survival in a seasonal
           environment: consequences for population dynamics
    • Abstract: 1.In seasonal populations, vital rates are not only determined by the direct effects of density at the beginning of each season, but also by density at the beginning of past seasons. Such delayed density‐dependence can arise via non‐lethal effects on individuals that carry‐over to influence per capita rates. 2.In this study, we examine (a) whether parental breeding density influences offspring size, (b) how this could carry over to affect offspring survival during the subsequent non‐breeding period, and (c) the population consequences of this relationship. 3.Using Drosophila melanogaster, the common fruit fly, submitted to distinct breeding and non‐breeding seasons, we first used a controlled lab experiment to show that high parental breeding density leads to small offspring size, which then affects offspring survival during the non‐breeding period but only at high non‐breeding densities. 4.Similar to our experimental results, we then show that a model with the interaction between parental breeding density and offspring density at the beginning of the non‐breeding season best explained offspring survival over 36 replicated generations. 5.Finally, we developed a bi‐seasonal model to show that the positive relationship between parental density and offspring survival dampened fluctuations in population size between breeding and non‐breeding seasons. 6.These results highlight how variation in parental density can lead to differences in offspring quality which result in important non‐lethal effects that carry‐over to influence per capita rates the following season, and demonstrate how this phenomenon can have important implications for the long‐term dynamics of seasonal populations. This article is protected by copyright. All rights reserved.
  • Year‐round effects of climate on demographic parameters of an
           arctic–nesting goose species
    • Abstract: 1. Understanding how climate change will affect animal population dynamics remains a major challenge, especially in long‐distant migrants exposed to different climatic regimes throughout their annual cycle. 2. We evaluated the effect of temperature throughout the annual cycle on demographic parameters (age‐specific survival and recruitment, breeding propensity, and fecundity) of the greater snow goose (Chen caerulescens atlantica L.), an arctic‐nesting species. Since this is a hunted species, we used the theory of exploited populations to estimate hunting mortality separately from natural mortality in order to evaluate climatic effects only on the latter form of mortality. 3. Our analysis was based on a 22‐year marking study (n = 27,150 females) and included live recaptures at the breeding colony and dead recoveries from hunters. We tested the effect of climatic covariates by applying a procedure that accounts for unexplained environmental variation in the demographic parameter to a multistate Capture‐Mark‐Recapture recruitment model. 4. Breeding propensity, clutch size and hatching probability all increased with high temperatures on the breeding grounds. First‐year survival to natural causes of mortality increased when temperature was high at the end of the summer whereas adult survival was not affected by temperature. On the contrary, accession to reproduction decreased with warmer climatic conditions during the non‐breeding season. 5. Survival was strongly negatively related to hunting mortality in adults, as expected, but not in first‐year birds, which suggests the possibility of compensation between natural and hunting mortality in the latter group. 6. We show that events occurring both at and away from the breeding ground can affect the demography of migratory birds, either directly or through carry‐over effects, and sometimes in opposite ways. This highlights the need to account for the whole life cycle of an animal when attempting to project the response of populations to future climatic changes. This article is protected by copyright. All rights reserved.
  • Ant functional responses along environmental gradients
    • Abstract: Understanding species distributions and diversity gradients is a central challenge in ecology and requires prior knowledge of the functional traits mediating species’ survival under particular environmental conditions. While the functional ecology of plants has been reasonably well explored, much less is known about that of animals. Ants are among the most diverse, abundant, and ecologically significant organisms on earth, and they perform a great variety of ecological functions. In this study, we analyze how the functional species traits present in ant communities vary along broad gradients in climate, productivity, and vegetation type in the southwestern Mediterranean. To this end, we compiled one of the largest animal databases to date: it contains information on 211 local ant communities (including eight climate variables, productivity, and vegetation type) and 124 ant species, for which 10 functional traits are described. We used traits that characterize different dimensions of the ant functional niche with respect to morphology, life‐history and behavior at both individual‐ and colony‐level. We calculated two complementary functional trait community indices (‘trait average’ and ‘trait dissimilarity’) for each trait, and we analyzed how they varied along the three different gradients using generalized least squares (GLS) models that accounted for spatial autocorrelation. Our results show that productivity, vegetation type, and, to a lesser extent, each climate variable per se might play an important role in shaping the occurrence of functional species traits in ant communities. Among the climate variables, temperature and precipitation seasonality had a much higher influence on functional responses than their mean values, whose effects were almost lacking. Our results suggest that strong relationships might exist between the abiotic environment and the distribution of functional traits among southwestern Mediterranean ant communities. This finding indicates that functional traits may modulate the responses of ant species to the environment. Since these traits act as the link between species distributions and the environment, they could potentially be used to predict community changes under future global change scenarios. This article is protected by copyright. All rights reserved.
  • Revisiting food‐based models of territoriality in solitary predators
    • Abstract: 1. Food availability is considered a major factor determining spacing behaviour in territorial species, especially for females. Theoretically, spatial overlap (considered the opposite of territoriality) and food availability are related in a non‐linear manner (hypothesized inverted‐U function), with high overlap levels at the extremes of a food availability gradient and low overlap at intermediate levels of this gradient. Similar patterns are expected for encounter frequencies owing to its expected correlation with spatial overlap. However, these predictions have rarely been tested in highly structured social systems on a broad gradient of food availability, which implicitly requires experimental manipulation. 2. We test these predictions in a solitary, territorial and trophic specialist, the Iberian lynx Lynx pardinus, taking advantage of a three‐decade dataset of spatial behaviour in different scenarios of food availability (i.e. rabbit density). 3. In contrast with expectations, home range overlap among resident females was low (median overlap index = 0.08, range 0‐0.57) and core area overlap was nearly nil (median overlap index = 0, range 0‐0.22) throughout the entire gradient of prey availability. Furthermore, spatial associations between pairs of females were negligible regardless marked variation in prey availability. Therefore, we did not find support for a model of flexible lynx territoriality driven by food availability. 4. Our results suggest that the exclusive use of space in the Iberian lynx was not related to food. Lack of influence of prey availability on lynx territoriality may be adaptive to cope with the consequences of frequent drought‐induced periods of prey scarcity or other disturbance typically affecting wild rabbit populations in Mediterranean environments. Thus, lynx would adopt an obstinate strategy of territoriality that consists in defending exclusive areas across a broad range of resource availability ensuring an exclusive access to the minimum amount of prey necessary for survival and eventually reproduction even during periods of prey scarcity. However, we found signs that territoriality was influenced by lynx density in a non‐linear fashion. Our results suggest the occurrence of population regulation through territoriality in this species. This article is protected by copyright. All rights reserved.
  • Experimentally decoupling reproductive investment from energy storage to
           test the functional basis of a life‐history tradeoff
    • Abstract: The ubiquitous life‐history tradeoff between reproduction and survival has long been hypothesized to reflect underlying energy‐allocation tradeoffs between reproductive investment and processes related to self‐maintenance. Although recent work has questioned whether energy‐allocation models provide sufficient explanations for the survival cost of reproduction, direct tests of this hypothesis are rare, especially in wild populations. This hypothesis was tested in a wild population of brown anole lizards (Anolis sagrei) using a two‐step experiment. First, stepwise variation in reproductive investment was created using unilateral and bilateral ovariectomy (OVX) along with intact (SHAM) control. Next, this manipulation was decoupled from its downstream effects on energy storage by surgically ablating the abdominal fat stores from half of the females in each reproductive treatment. As predicted, unilateral OVX (intermediate reproductive investment) induced levels of growth, body condition, fat storage, and breeding‐season survival that were intermediate between the high levels of bilateral OVX (no reproductive investment) and the low levels of SHAM (full reproductive investment). Ablation of abdominal fat bodies had a strong and persistent effect on energy stores, but it did not influence post‐breeding survival in any of the three reproductive treatments. This suggests that the energetic savings of reduced reproductive investment does not directly enhance post‐breeding survival, with the caveat that only one aspect of energy storage was manipulated and OVX itself had no overall effect on post‐breeding survival. This study supports the emerging view that simple energy‐allocation models may often be insufficient as explanations for the life‐history tradeoff between reproduction and survival. This article is protected by copyright. All rights reserved.
  • Cheetahs and wild dogs show contrasting patterns of suppression by lions
    • Abstract: Top predators can dramatically suppress populations of smaller predators, with cascading effects throughout communities, and this pressure is often unquestioningy accepted as a constraint on mesopredator populations. In this study, we reassess whether African lions suppress populations of cheetahs and African wild dogs, and examine possible mechanisms for coexistence between these species. Using long‐term records from Serengeti National Park, we tested 30 years of population data for evidence of mesopredator suppression and we examined six years of concurrent radio‐telemetry data for evidence of large‐scale spatial displacement. The Serengeti lion population nearly tripled between 1966 and 1998; during this time, wild dogs declined but cheetah numbers remained largely unchanged. Prior to their local extinction, wild dogs primarily occupied low‐lion density areas, and apparently abandoned the long‐term study area as the lion population “saturated” the region. In contrast, cheetahs mostly utilized areas of high lion density, and the stability of the cheetah population indicates that neither high levels of lion‐inflicted mortality nor behavioral avoidance inflict sufficient demographic consequences to translate into population‐level effects. Population data from fenced reserves in southern Africa revealed a similar contrast between wild dogs and cheetahs in their ability to coexist with lions. These findings demonstrate differential responses of subordinate species within the same guild and challenge a widespread perception that lions undermine cheetah conservation efforts. Paired with several recent studies that document fine‐scale lion‐avoidance by cheetahs, this study further highlights fine‐scale spatial avoidance as a possible mechanism for mitigating mesopredator suppression. This article is protected by copyright. All rights reserved.
  • Disentangling the effects of exposure and susceptibility on transmission
           of the zoonotic parasite Schistosoma mansoni
    • Abstract: For all parasites, transmission is composed of two processes: host contact with parasites (“exposure”) and risk of infection given such contact (“susceptibility”). Classic models, such as mass action (density‐dependent) transmission, lump these processes together. However, separating these processes could enhance predictions for disease dynamics, especially for free‐living parasites. Here we outline three transmission models that partition exposure and susceptibility. Using data from a study of Schistosoma mansoni (trematode) infections in Biomphalaria glabrata snails, we competed these three models against four alternative models, including the mass action model (which lumps exposure and susceptibility). The models that separately accounted for exposure and susceptibility best predicted prevalence across the density gradients of hosts and parasites, outperforming all other models based on Akaike Information Criterion. When embedded into a dynamic epidemiological model, the exposure‐explicit models all predicted lower equilibrium densities of infected snails and human‐infectious cercariae. Thus, population‐level epidemiological models that utilize the classic mass action transmission model might overestimate human risk of schistosomiasis. More generally, the presented approach for disentangling exposure and susceptibility can distinguish between behavioral and immunological resistance, identify mechanisms of “disease dilution”, and provide a more complete dissection of drivers of parasite transmission. This article is protected by copyright. All rights reserved.
  • The effect of fire on habitat selection of mammalian herbivores: the role
           of body size and vegetation characteristics
    • Abstract: 1. Given the role of fire in shaping ecosystems, especially grasslands and savannahs, it is important to understand its broader impact on these systems. Post‐fire stimulation of plant nutrients is thought to benefit grazing mammals and explain their preference for burned areas. However, fire also reduces vegetation height and increases visibility, thereby potentially reducing predation risk. Consequently, fire may be more beneficial to smaller herbivores, with higher nutritional needs and greater risks of predation. 2. We tested the impacts of burning on different sized herbivores’ habitat preference in Serengeti National Park, as mediated by burning's effects on vegetation height, live to dead biomass ratio, and leaf nutrients. 3. Burning caused a less than four month increase in leaf nitrogen (N), and leaf non‐N nutrients (copper (Cu), potassium (K), and magnesium (Mg)), and a decrease in vegetation height and live:dead biomass. During this period, total herbivore counts were higher on burned areas. Generally, smaller herbivores preferred burned areas, more strongly than larger herbivores. 4. Unfortunately, it was not possible to determine the vegetation characteristics that explained burned area preference for each of the herbivore species observed. However, total herbivore abundance and impala (Aepyceros melampus) preference for burned areas was due to the increases in non‐N nutrients caused by burning. 5. These findings suggest that burned area attractiveness to herbivores is mainly driven by changes to forage quality and not potential decreases in predation risk caused by reductions in vegetation height. This article is protected by copyright. All rights reserved.
  • Predator avoidance during reproduction: diel movements by spawning sockeye
           salmon between stream and lake habitats
    • Abstract: 1. Daily movements of mobile organisms between habitats in response to changing trade‐offs between predation risk and foraging gains are well established; however, less in known about whether similar tactics are used during reproduction, a time period when many organisms are particularly vulnerable to predators. 2. We investigated the reproductive behaviour of adult sockeye salmon (Oncorhynchus nerka) and the activity of their principal predator, brown bears (Ursus arctos), on streams in southwestern Alaska. Specifically, we continuously monitored movements of salmon between lake habitat, where salmon are invulnerable to bears, and three small streams, where salmon spawn and are highly vulnerable to bears. We conducted our study across 2 years that offered a distinct contrast in bear activity and predation rates. 3. Diel movements by adult sockeye salmon between stream and lake habitat were observed in 51.3 ± 17.7% [mean ± SD] of individuals among years and sites. Fish that moved tended to hold in the lake for most of the day, and then migrated into spawning streams during the night coincident with when bear activity on streams tended to be lowest. Additionally, cyclic movements between lakes and spawning streams were concentrated earlier in the spawning season. 4. Individuals that exhibited diel movements had longer average reproductive life‐spans than those who made only one directed movement into a stream. However, the relative effect was dependent on the timing of bear predation, which varied between years. When predation pressure primarily occurred early in the spawning run (i.e., during the height of the diel movements), movers lived 120 – 310% longer than non‐movers. If predation pressure was concentrated later in the spawning run (i.e., when most movements had ceased), movers only lived 10‐60% longer. 5. Our results suggest a dynamic trade‐off in reproductive strategies of sockeye salmon; adults must be in the stream to reproduce, but must also avoid predation long enough to spawn. Given the inter‐annual variation in the timing and intensity of predation pressure, the advantages of a particular movement strategy will likely vary among years. Regardless, movements by salmon allowed individuals to exploit fine‐scale habitat heterogeneity during reproduction that appears to be a strategy to reduce predation risk on the spawning grounds. This article is protected by copyright. All rights reserved.
  • Community‐level Demographic Consequences of Urbanization: An
           Ecological Network Approach
    • Abstract: Ecological networks are known to influence ecosystem attributes, but we poorly understand how interspecific network structure affect population demography of multiple species, particularly for vertebrates. Establishing the link between network structure and demography is at the crux of being able to use networks to understand population dynamics and to inform conservation. We addressed the critical but unanswered question, does network structure explain demographic consequences of urbanization' We studied 141 ecological networks representing interactions between plants and nesting birds in forests across an urbanization gradient in Ohio, USA from 2001‐2011. Nest predators were identified by video‐recording nests and surveyed from 2004‐2011. As landscapes urbanized, bird‐plant networks were more nested, less compartmentalized, and dominated by strong interactions between a few species (i.e., low evenness). Evenness of interaction strengths promoted avian nest survival, and evenness explained demography better than urbanization, level of invasion, numbers of predators, or other qualitative network metrics. Highly uneven networks had approximately half the nesting success as the most even networks. Thus, nest survival reflected how urbanization altered species interactions, particularly with respect to how nest placement affected search efficiency of predators. The demographic effects of urbanization were not direct, but were filtered through bird‐plant networks. This study illustrates how network structure can influence demography at the community level, and further, that knowledge of species interactions and a network approach may be requisite to understanding demographic responses to environmental change. This article is protected by copyright. All rights reserved.
  • The smell of good food: volatile infochemicals as resource quality
    • Abstract: 1.Foraging success generally depends on various environmental and physiological factors. Particularly for organisms with limited motility such as gastropods, food searching is a very cost‐intensive process. As energy gain through foraging is dependent on both resource quality and quantity, consumers have to be able to differentiate between varying resource items. 2.The effectiveness of food searching could be increased through the perception of diet‐derived chemical signals that convey information about a food resource's quality over a certain distance. This strategy would clearly help to optimize movement decisions. 3.In this study, we investigated the foraging behaviour of a freshwater gastropod towards volatile signal substances released from benthic algae grown under high and low nutrient availability, representing high and low food quality, using behavioural assays in the laboratory. 4.Our results demonstrate that volatile organic compounds (VOCs) serve as foraging kairomones for these aquatic, benthic herbivores. Further, we were able to show for the first time that snails are able to differentiate between high and low quality food sources only by the perception of food odours alone (volatile infochemicals). 5.Gas chromatography coupled with mass spectrometry demonstrated quantitative as well as qualitative differences in the chemical composition of the VOC's bouquet, dependent on algal nutrient content. 6.Our results suggest that the recognition of resource quality via the reception of signal substances is likely to be adaptive for consumers with low mobility to maximize ingestion of high quality resources. This article is protected by copyright. All rights reserved.
  • A trophic cascade induced by predatory ants in a fig‐fig wasp
    • Abstract: 1.A trophic cascade occurs when predators directly decrease the densities, or change the behaviour, of herbivores and thus indirectly increase plant productivity. The predator‐herbivore‐plant context is well‐known, but some predators attack species beneficial to plants (e.g. pollinators) and/or enemies of herbivores (e.g. parasites) and their role in the dynamics of mutualisms remains largely unexplored. 2.We surveyed the predatory ant species and studied predation by the dominant ant species, the weaver ant Oecophylla smaragdina, associated with the fig tree Ficus racemosa in southwest China. We then tested the effects of weaver ants on the oviposition behaviour of pollinating and non‐pollinating fig wasps in an ant exclusion experiment. The effects of weaver ants on fig wasp community structure and fig seed production were then compared between trees with and without O. smaragdina. 3.Oecophylla smaragdina captured more non‐pollinating wasps (Platyneura mayri) than pollinators as the insects arrived to lay eggs. When ants were excluded, more non‐pollinators laid eggs into figs and fewer pollinators entered figs. Furthermore, trees with O. smaragdina produced more pollinator offspring and fewer non‐pollinator offspring, shifting the community structure significantly. In addition, F. racemosa produced significantly more seeds on trees inhabited by weaver ants. 4.Oecophylla smaragdina predation reverses the dominance of the two commonest wasp species at the egg‐laying stage, and favours the pollinators. This behavioural pattern is mirrored by wasp offspring production, with pollinators’ offspring dominating figs produced by trees inhabited by weaver ants, and offspring of the non‐pollinator P. mayri most abundant in figs on trees inhabited by other ants. 5.Overall, our results suggest that predation by weaver ants limits the success of the non‐pollinating P. mayri and therefore indirectly benefits the mutualism by increasing the reproductive success of both the pollinators and the plant. Predation is thus a key functional factor that can shape the community structure of a pollinator‐plant mutualistic system. This article is protected by copyright. All rights reserved.
  • The marine diversity spectrum
    • Abstract: Distributions of species body sizes within a taxonomic group, for example, mammals, are widely studied and important because they help illuminate the evolutionary processes that produced these distributions. Distributions of the sizes of species within an assemblage delineated by geography instead of taxonomy (all the species in a region regardless of clade) are much less studied but are equally important and will illuminate a different set of ecological and evolutionary processes. We develop and test a mechanistic model of how diversity varies with body mass in marine ecosystems. The model predicts the form of the ‘diversity spectrum’, which quantifies the distribution of species' asymptotic body masses, is a species analogue of the classic size spectrum of individuals, and which we have found to be a new and widely applicable description of diversity patterns. The marine diversity spectrum is predicted to be approximately linear across an asymptotic mass range spanning seven orders of magnitude. Slope −0·5 is predicted for the global marine diversity spectrum for all combined pelagic zones of continental shelf seas, and slopes for large regions are predicted to lie between −0·5 and −0·1. Slopes of −0·5 and −0·1 represent markedly different communities: a slope of −0·5 depicts a 10‐fold reduction in diversity for every 100‐fold increase in asymptotic mass; a slope of −0·1 depicts a 1·6‐fold reduction. Steeper slopes are predicted for larger or colder regions, meaning fewer large species per small species for such regions. Predictions were largely validated by a global empirical analysis. Results explain for the first time a new and widespread phenomenon of biodiversity. Results have implications for estimating numbers of species of small asymptotic mass, where taxonomic inventories are far from complete. Results show that the relationship between diversity and body mass can be explained from the dependence of predation behaviour, dispersal, and life history on body mass, and a neutral assumption about speciation and extinction. This work demonstrates and explains for the first time a global phenomenon of how species diversity varies with body size in marine systems.
  • Towards an energetic landscape: broad‐scale accelerometry in
           woodland caribou
    • Abstract: Energetic balance is a central driver of individual survival and population change, yet estimating energetic costs in free and wide ranging animals presents a significant challenge. Animal‐borne activity monitors (using accelerometer technology) present a promising method of meeting this challenge and opens new avenues for exploring energetics in natural settings. To determine the behaviours and estimated energetic costs associated with a given activity level, three captive reindeer (Rangifer tarandus tarandus) at the Toronto Zoo were fitted with collars and observed for 53 hours. Activity patterns were then measured over thirteen months for 131 free‐ranging woodland caribou (R. t. caribou) spanning 450,000 km2 in northern Ontario. The captive study revealed a positive but decelerating relationship between activity level and energetic costs inferred from previous behavioural studies. Field‐based measures of activity were modelled against individual displacement, vegetation abundance (NDVI), snow depth, and temperature, and the best fit model included all parameters and explained over half of the variation in the data. Individual displacement was positively related to activity levels, suggesting that broad differences in energetic demands are influenced by variation in movement rates. After accounting for displacement, activity was highest at intermediate levels of vegetation abundance, presumably due to foraging behaviour. Snow depth, probably associated with digging for winter forage, moderately increased activity. Activity levels increased significantly at the coldest winter temperatures, suggesting the use of behavioural thermoregulation by caribou. These interpretations of proximate causal factors should be regarded as hypotheses subject to validation under normal field conditions. These results illustrate the landscape characteristics that increase energetic demands for caribou and confirm the great potential for the use of accelerometry in studies of animal energetics. This article is protected by copyright. All rights reserved.
  • Heterogeneous hosts: how variation in host size, behaviour, and immunity
           affect parasite aggregation in an experimental system
    • Abstract: 1.Infection heterogeneity is one of the most fundamental patterns in disease ecology, yet surprisingly few studies have experimentally explored its underlying drivers. Here, we used large‐scale field assessments to evaluate the degree of parasite aggregation within amphibian host populations followed by a novel experimental approach to assess the potential influence of host size, behaviour, and immunity in reproducing such heterogeneity. 2.Among 227 wetlands, 2,468 hosts, and 7 parasite species, infections were consistently aggregated among host individuals within populations of the Pacific chorus frog (Pseudacris regilla). For each parasite species, the relationship between the logmean and logvariance of infection load was strongly linear (R2: 0.91‐0.98) with a slope between 1.37 and 1.67, indicative of aggregation relative to the expected Poisson slope of unity. 3.In laboratory trials with P. regilla and the most virulent trematode (Ribeiroia ondatrae), experimental reductions of either host immunity (through corticosterone exposure) or anti‐parasite behaviours (through anesthesia exposure) increased parasite infection loads in isolated hosts by 62 to 102% relative to unmanipulated individuals. In a second experiment designed to test how variation in host immunity, behaviour and body size affected variation in infection load within small groups (dyads), a reduction in immune function or behaviour of one host significantly amplified infection heterogeneity within the group, effectively doubling the variance‐to‐mean ratio. However, immunity affected aggregation only in the absence of behavioural manipulation, and changing the size distribution of hosts did not appreciably affect aggregation. 4.Using Taylor's Power Law to integrate field and laboratory data, we found that only treatments involving behavioural reductions achieved aggregation levels comparable to natural host populations. Thus, despite their short duration, our treatments generated heterogeneity in infection loads similar to natural observations. 5.These results emphasize how, alongside extrinsic variation in parasite exposure risk, individual host attributes generally and behaviour in particular have the potential to influence infection success and parasite aggregation. Continued integration of infection heterogeneity research across space, among host species, and over time has important implications for understanding and managing human and wildlife diseases. This article is protected by copyright. All rights reserved.
  • Predictors of malaria infection in a wild bird population: Landscape level
           analyses reveal climatic and anthropogenic factors
    • Abstract: 1. How the environment influences the transmission and prevalence of disease in a population of hosts is a key aspect of disease ecology. The role that environmental factors play in host‐pathogen systems has been well studied at large scales, i.e. differences in pathogen pressures among separate populations of hosts, or across land masses. However, despite considerable understanding of how environmental conditions vary at fine spatial scales, the effect of these parameters on host‐pathogen dynamics at such scales has been largely overlooked. 2. Here we used a combination of molecular screening and GIS‐based analysis to investigate how environmental factors determine the distribution of malaria across the landscape in a population of Berthelot's pipit (Anthus berthelotii, Bolle 1862) on the island of Tenerife (Canary Islands, Spain) using spatially explicit models that account for spatial autocorrelation. 3. Minimum temperature of the coldest month was found to be the most important predictor of malaria infection at the landscape scale across this population. Additionally, anthropogenic factors such as distance to artificial water reservoirs and distance to poultry farms were important predictors of malaria. A model including these factors, and the interaction between distance to artificial water reservoirs and minimum temperature, best explained the distribution of malaria infection in this system. 4. These results suggest that levels of malaria infection in this endemic species may be artificially elevated by the impact of humans. 5. Studies such as the one described here improve our understanding of how environmental factors, and their heterogeneity, affect the distribution of pathogens within wild populations. The results demonstrate the importance of measuring fine scale variation ‐ and not just regional effects ‐ in order to understand how environmental variation can influence wildlife diseases. Such understanding is important for predicting the future spread and impact of disease and may help inform disease management programmes as well as the conservation of specific host species. This article is protected by copyright. All rights reserved.
  • An evolutionary perspective on reproductive individual heterogeneity in a
           marine vertebrate
    • Abstract: 1.Although the quantification of individual heterogeneity in wild populations’ vital rates has recently attracted growing interest among ecologists, the investigation of its evolutionary consequences remains limited, mainly because of the difficulties in assessing fitness and heritability from field studies on free‐ranging animals. In the presence of individual variability, evaluation of fitness consequences can notably be complicated by the existence of trade‐offs among different vital rates. 2.In this study, to further assess the evolutionary significance of previously quantified levels of individual heterogeneity in female Weddell seal (Leptonychotes weddellii Lesson) reproductive rates (Chambert et al. 2013), we investigated how several life history characteristics of female offspring were related to their mother's reproductive rate, as well as to other maternal traits (age and experience) and environmental conditions at birth. 3.The probability and age of first reproduction (recruitment) of female offspring was not related to their mother's reproductive rate, suggesting the absence of a maternal trade‐off between the number and quality of offspring a female produces. Evidence of a positive, but relatively weak, relationship between the reproductive rates of a mother and her female offspring was found, suggesting some degree of heritability in this trait. 4.Using a simulation approach based on these statistical findings, we showed that substantial differences in the number of grandchildren, produced through female progeny can be expected among females with different reproductive rates. 5.Despite the presence of substantial stochastic variability, due to environmental fluctuations and other unidentified mechanisms, and in light of the fact that the metrics obtained do not provide a full measure of real fitness, our results do suggest that the individual reproductive variability found in female Weddell seals could potentially have important fitness consequences.
  • Life‐history diversity and its importance to population stability
           and persistence of a migratory fish: steelhead in two large North American
    • Abstract: 1.Life‐history strategies can buffer individuals and populations from environmental variability. For instance, it is possible that asynchronous dynamics among different life‐histories can stabilize populations through portfolio effects. 2.Here we examine life‐history diversity and its importance to stability for an iconic migratory fish species. In particular, we examined steelhead (Oncorhynchus mykiss), an anadromous and iteroparous salmonid, in two large, relatively pristine, watersheds, the Skeena and Nass, in northwestern British Columbia, Canada. We synthesized life‐history information derived from scales collected from adult steelhead (N = 7227) in these watersheds across a decade. 3.These migratory fishes expressed 36 different manifestations of the anadromous life‐history strategy, with 16 different combinations of freshwater and marine ages, 7.6% of fish performing multiple spawning migrations, and up to 4 spawning migrations. Furthermore, in the Nass watershed, different life‐histories were differently prevalent through time—three different life‐histories were the most prevalent in a given year and no life‐history ever represented more than 45% of the population. These asynchronous dynamics among life‐histories decreased the variability of numerical abundance and biomass of the aggregated population so that it was more than 20% more stable than the stability of the weighted average of specific life‐histories, evidence of a substantial portfolio effect. Year of ocean entry was a key driver of dynamics; the median correlation coefficient of abundance of life‐histories that entered the ocean the same year was 2.5 times higher than the median pairwise coefficient of life‐histories that entered the ocean at different times. Simulations illustrated how different elements of life‐history diversity contribute to stability and persistence of populations. 4.This study provides evidence that life‐history diversity can dampen fluctuations in population abundances and biomass via portfolio effects. Conserving genetic integrity and habitat diversity in this and other large watersheds can enable a diversity of life‐histories that increases stability to environmental variability. This article is protected by copyright. All rights reserved.
  • Dispersal‐mediated effect of microhabitat availability and density
           dependence determine population dynamics of a forest‐floor web
    • Abstract: 1.Landscapes in nature can be viewed as a continuum of small total habitable area with high fragmentation to widely spreading habitats. The dispersal‐mediated rescue effect predominates in the former landscapes, while classical density‐dependent processes generally prevail in widely spread habitats. A similar principle should be applied to populations of organisms utilizing microhabitats in limited supply. 2.To test this hypothesis, we examined the population dynamics of a web spider, Neriene brongersmai, in 16 populations with varying degrees of microhabitat availability, and we explored whether: (1) high microhabitat availability improves survival rate during density‐independent movement, while the resultant high density reduces survival rate in a density‐dependent manner; and (2) temporal population stability increases with microhabitat availability at the population level. Furthermore, we conducted two types of field experiments to verify whether high microhabitat availability actually reduces mortality associated with web‐site movement. 3.Field observations revealed that demographic change in N. brongersmai populations was affected by three factors at different stages, namely, the microhabitat limitation from the early to late juvenile stages, the density dependence from the late juvenile to adult stages, and the food limitation from the adult to the next early juvenile stages. In addition, there was a tendency for a positive association between population stability and microhabitat availability at the population level. 4.A small‐scale experiment, where the frequency of spider web relocation was equalized artificially, revealed that high microhabitat availability elevated the survival rate during a movement event between web‐sites. The larger spatiotemporal scale experiment also revealed an improved spider survival rate following treatment with high microhabitat availability, even though spider density was kept at a relatively low level. 5.The population dynamics of N. brongersmai can be determined primarily by density‐independent processes based on web‐site fragmentation and density‐dependent processes driven by interference competition. We conclude that, depending on the amount of habitat resources, the relative importance of the two contrasting paradigms—equilibrium and non‐equilibrium—appears to vary, even within a particular system. This article is protected by copyright. All rights reserved.
  • Individual and sex‐specific differences in intrinsic growth rate
           covary with consistent individual differences in behaviour
    • Abstract: 1.The evolutionary causes of consistent individual differences in behavior are currently a source of debate. A recent hypothesis suggests that consistent individual differences in life‐history productivity (growth and/or fecundity) may covary with behavioral traits that contribute to growth‐mortality trade‐offs, such as risk‐proneness (boldness) and foraging activity (voraciousness). It remains unclear, however, to what extent individual behavioral and life‐history profiles are set early in life, or are a more flexible result of specific environmental or developmental contexts that allow bold and active individuals to acquire more resources. 2.Longitudinal studies of individually housed animals under controlled conditions can shed light on this question. Since growth and behaviour can both vary within individuals (they are labile), studying between‐individual correlations in behaviour and growth rate requires repeated scoring for both variables over an extended period of time. However, such a study has not yet been done. 3.Here, we repeatedly measured individual mass 7‐times each, boldness 40‐times each, and voracity 8‐times each during the first four months of life on 90 individually‐housed crayfish (Cherax destructor). Animals were fed ad‐libitum, generating a context where individuals can express their intrinsic growth rate (i.e. growth capacity), but in which bold and voracious behaviour is not necessary for high resource acquisition (crayfish can and do hoard food back to their burrow). 4.We show that individuals that were consistently bold over time during the day were also bolder at night, were more voracious, and maintained higher growth rates over time than shy individuals. Independent of individual differences, we also observed that males were faster growing, bolder, and more voracious than females. 5.Our findings imply that associations between bold behaviour and fast growth can occur in unlimited food contexts where there is no necessary link between bold behaviour and resource acquisition – offering support for the ‘personality‐ productivity’ hypothesis. We suggest future research should study links between consistent individual differences in behaviour and life‐history under a wider range of contexts, in order to shed light on the role of biotic and abiotic conditions in the strength, direction and stability of their covariance. This article is protected by copyright. All rights reserved.
  • Ecological opportunities and intraspecific competition alter trophic niche
           specialization in an opportunistic stream predator
    • Abstract: Many generalist populations are composed of specialized individuals that use a narrow part of the population's niche. Ecological theories predict that individual specialization and population trophic niche are determined by biotic interactions and resource diversity emerging from environmental variations (i.e., ecological opportunities). However, due to the paucity of empirical and experimental demonstrations, the genuine importance of each of these drivers in determining trophic niche attributes is not fully appreciated. The present study aimed at determining the population level and individual responses of brown trout (Salmo trutta) to variations in ecological opportunities (terrestrial prey inputs) and autochthonous prey communities among ten stream reaches along a riparian condition gradient using individual longitudinal monitoring and stable isotope analyses. Our results suggested that trophic niche diversity varied along the environmental gradient while individual trophic specialization was indirectly driven by ecological opportunities through strengthened intraspecific competition. Individual diet was repeatable over the study period and the growth rate of juvenile brown trout increased with their specialization for aquatic predatory invertebrates. Our findings highlight the dual influences of intraspecific competition and ecological opportunities on individual trophic specialization and trophic niche construction. This article is protected by copyright. All rights reserved.
  • Habitat degradation is threatening reef replenishment by making fish
    • Abstract: Habitat degradation is one of the “Big Five” drivers of biodiversity loss. However, the mechanisms responsible for this progressive loss of biodiversity are poorly understood. In marine ecosystems, corals play the role of ecosystem engineers, providing essential habitat for hundreds of species and hence their health is crucial to the stability of the whole ecosystem. Climate change is causing coral bleaching and degradation, and while this has been known for a while, little do we know about the cascading consequences of these events on the complex interrelationships between predators and their prey. The goal of our study was to investigate, under completely natural conditions, the effect of coral degradation on predator‐prey interactions. Settlement‐stage ambon damselfish (Pomacentrus amboinensis), a common tropical fish, were released on patches of healthy or dead corals, and their behaviours in situ were measured, along with their response to injured conspecific cues, a common risk indicator. This study also explored the effect of habitat degradation on natural levels of mortality at a critical life history transition. We found that juveniles in dead corals displayed risk‐prone behaviours, sitting further away and higher up on the reef patch, and failed to respond to predation cues, compared to those on live coral patches. In addition, in situ survival experiments over 48 hrs indicated that juveniles on dead coral habitats had a 75% increase in predation‐related mortality, compared to fish released on live, healthy coral habitats. Our results provide the first of many potential mechanisms through which habitat degradation can impact the relationship between prey and predators in the coral reef ecosystem. As the proportion of dead coral increases, the recruitment and replenishment of coral reef fishes will be threatened, and so will the level of diversity in these biodiversity hotspots. This article is protected by copyright. All rights reserved.
  • Frequent and seasonally variable sublethal anthrax infections are
           accompanied by short‐lived immunity in an endemic system
    • Abstract: 1. Few studies have examined host‐pathogen interactions in wildlife from an immunological perspective, particularly in the context of seasonal and longitudinal dynamics. In addition, though most ecological immunology studies employ serological antibody assays, endpoint titer determination is usually based on subjective criteria and needs to be made more objective. 2. Despite the fact that anthrax is an ancient and emerging zoonotic infectious disease found worldwide, its natural ecology is not well understood. In particular, little is known about the adaptive immune responses of wild herbivore hosts against Bacillus anthracis. 3. Working in the natural anthrax system of Etosha National Park, Namibia, we collected 154 serum samples from plains zebra (Equus quagga), 21 from springbok (Antidorcas marsupialis), and 45 from African elephants (Loxodonta africana) over 2‐3 years, resampling individuals when possible for seasonal and longitudinal comparisons. We used enzyme‐linked immunosorbent assays to measure anti‐anthrax antibody titers and developed three increasingly conservative models to determine endpoint titers with more rigorous, objective mensuration. 4. Between 52‐87% of zebra, 0‐15% of springbok, and 3‐52% of elephants had measurable anti‐anthrax antibody titers, depending on the model used. While the ability of elephants and springbok to mount anti‐anthrax adaptive immune responses is still equivocal, our results indicate that zebra in ENP often survive sublethal anthrax infections, encounter most B. anthracis in the wet season, and can partially booster their immunity to B. anthracis. 5. Thus, rather than being solely a lethal disease, anthrax often occurs as a sublethal infection in some susceptible hosts. Though we found that adaptive immunity to anthrax wanes rapidly, subsequent and frequent sublethal B. anthracis infections cause maturation of anti‐anthrax immunity. By triggering host immune responses, these common sublethal infections may act as immunomodulators and affect population dynamics through indirect immunological and co‐infection effects. 6. In addition, with our three endpoint titer models, we introduce more mensuration rigor into serological antibody assays, even under the often‐restrictive conditions that come with adapting laboratory immunology methods to wild systems. With these methods we identified significantly more zebras responding immunologically to anthrax than have previous studies using less comprehensive titer analyses. This article is protected by copyright. All rights reserved.
  • Immigrants are attracted by local pre‐breeders and recruits in a
           seabird colony
    • Abstract: 1.Immigration is a major demographic factor shaping population dynamics. However, due to methodological difficulties, the extent of immigration and factors affecting immigration are insufficiently studied. This is also true for seabird colonies. 2.We estimated annual immigration based on a long‐term study of a colony of common terns Sterna hirundo marked with transponders, using a Bayesian integrated population model that links colony size and productivity with individual life histories. 3.Strong annual fluctuations in the number of immigrants were found. In order to identify whether colony‐specific covariates influenced immigration, we related the number of immigrants to various proxy variables for breeding site quality, specifically colony size, productivity, number of local subadults and local recruits. Numbers of local recruits and local subadults showed strong positive correlations with number of immigrants. 4.We found that variation in immigration rate had strongly contributed to variation in colony growth rate, more so than variation in local recruitment or adult survival. 5.Collectively, results suggest that immigration strongly affects colony growth rate, that the driving force behind immigration is natal dispersal and that immigrants were attracted by local recruits. This article is protected by copyright. All rights reserved.
  • Linking phenological shifts to species interactions through
           size‐mediated priority effects
    • Abstract: 1.Inter‐annual variation in seasonal weather patterns causes shifts in the relative timing of phenological events of species within communities, but we currently lack a mechanistic understanding of how these phenological shifts affect species interactions. Identifying these mechanisms is critical to predicting how inter‐annual variation affects populations and communities. 2.Species’ phenologies, particularly the timing of offspring arrival, play an important role in the annual cycles of community assembly. We hypothesize that shifts in relative arrival of offspring can alter interspecific interactions through a mechanism called size‐mediated priority effects (SMPE), in which individuals that arrive earlier can grow to achieve a body size advantage over those that arrive later. 3.In this study, we used an experimental approach to isolate and quantify the importance of SMPE for species interactions. Specifically, we simulated shifts in relative arrival of the nymphs of two dragonfly species to determine the consequences for their interactions as intraguild predators. 4.We found that shifts in relative arrival altered not only predation strength but also the nature of predator‐prey interactions. When arrival differences were great, SMPE allowed the early arriver to prey intensely upon the late arriver, causing exclusion of the late arriver from nearly all habitats. As arrival differences decreased, the early arriver's size advantage also decreased. When arrival differences were smallest, there was mutual predation, and the two species coexisted in similar abundances across habitats. Importantly, we also found a nonlinear scaling relationship between shifts in relative arrival and predation strength. Specifically, small shifts in relative arrival caused large changes in predation strength while subsequent changes had relatively minor effects. 5.These results demonstrate that SMPE can alter not only the outcome of interactions but also the demographic rates of species and the structure of communities. Elucidating the mechanisms that link phenological shifts to species interactions is crucial for understanding the dynamics of seasonal communities as well as for predicting the effects of climate change on these communities. This article is protected by copyright. All rights reserved.
  • Greater migratory propensity in hosts lowers pathogen transmission and
    • Abstract: 1.Animal migrations are spectacular and migratory species have been shown to transmit pathogens that pose risks to human health. Although migration is commonly assumed to enhance pathogen dispersal, empirical work indicates that migration can often have the opposite effect of lowering disease risk. 2.Key to assessing disease threats to migratory species is the ability to predict how migratory behaviour influences pathogen invasion success and impacts on migratory hosts, thus motivating a mechanistic understanding of migratory host‐pathogen interactions. 3.Here we develop a quantitative framework to examine pathogen transmission in animals that undergo two‐way directed migrations between wintering and breeding grounds annually. 4.Using the case of a pathogen transmitted during the hosts’ breeding season, we show that a more extreme migratory strategy (defined by the time spent away from the breeding site and the total distance migrated) lowers the probability of pathogen invasion. Moreover, if migration substantially lowers the survival probability of infected animals, then populations that spend comparatively less time at the breeding site or that migrate longer distances are less vulnerable to pathogen‐induced population declines. 5.These findings provide theoretical support for two non‐exclusive mechanisms proposed to explain how seasonal migration can lower infection risk: (i) escape from habitats where parasite transmission stages have accumulated, and (ii) selective removal of infected hosts during strenuous journeys. Our work further suggests that barriers to long distance movement could increase pathogen prevalence for vulnerable species, an effect already seen in some animal species undergoing anthropogenically induced migratory shifts. This article is protected by copyright. All rights reserved.
  • Using dynamic Brownian bridge movement modeling to measure temporal
           patterns of habitat selection
    • Abstract: 1.Accurately describing animal space use is vital to understanding how wildlife use habitat. Improvements in GPS technology continue to facilitate collection of telemetry data at high spatial and temporal resolutions. Application of the recently introduced dynamic Brownian bridge movement model (dBBMM) to such data is promising as the method explicitly incorporates the behavioural heterogeneity of a movement path into the estimated utilization distribution (UD). 2.Utilization distributions defining space use are normally estimated for time scales ranging from weeks to months, obscuring much of the fine scale information available from high volume GPS data sets. By accounting for movement heterogeneity, the dBBMM provides a rigorous, behaviourally‐based estimate of space use between each set of relocations. Focusing on UDs generated between individual sets of locations allows us to quantify fine scale circadian variation in habitat use. 3.We used the dBBMM to estimate UDs bounding individual time steps for three terrestrial species with different life histories to illustrate how the method can be used to identify fine scale variations in habitat use. We also demonstrate how dBBMM's can be used to characterize circadian patterns of habitat selection and link fine‐scale patterns of habitat use to behaviour. 4.We observed circadian patterns of habitat use that varied seasonally for a white‐tailed deer (Odocoileus virginianus) and coyote (Canis latrans). We found seasonal patterns in selection by the white‐tailed deer, and were able to link use of conifer forests and agricultural fields to behavioural state of the coyote. Additionally, we were able to quantify the date in which a Rio Grande wild turkey (Meleagris gallopavo intermedia) initiated laying as well as when during the day she was most likely to visit the nest site to deposit eggs. 5.The ability to quantify circadian patterns of habitat use may have important implications for research and management of wildlife. Additionally, the ability to link such patterns to behaviour may aid in the development of mechanistic models of habitat selection. This article is protected by copyright. All rights reserved.
  • Evidence of localized resource depletion following a natural colonization
           event by a large marine predator
    • Abstract: 1.For central place foragers, forming colonies can lead to extensive competition for prey around breeding areas and a zone of local prey depletion. As populations grow, this area of reduced prey can expand impacting foraging success and forcing animals to alter foraging behaviour. 2.Here, we examine a population of marine predators, the northern fur seal (Callorhinus ursinus), which colonized a recently formed volcanic island, and assess changes in foraging behaviour associated with increasing population density. Specifically, we measured pup production and adult foraging behaviour over a 15‐year period, during which the population increased 4‐fold. 3.Using measures of at‐sea movements and dive behaviour, we found clear evidence that as the population expanded animals were required to allot increasing effort to obtain resources. These changes in behaviour included longer duration foraging trips, farther distances travelled, a larger foraging range surrounding the island, and deeper maximum dives. 4.Our results suggest that as the northern fur seal population increased, local prey resources were depleted as a result of increased intraspecific competition. In addition, the recent slowing of population growth indicates that this population may be approaching carrying capacity just 31 years after a natural colonization event. 5.Our study offers insight into the dynamics of population growth and impacts of increasing population density on a large marine predator. Such data could be vital for understanding future population fluctuations that occur in response to the dynamic environment, as natural and anthropogenic factors continue to modify marine habitats. This article is protected by copyright. All rights reserved.
  • Behavioral and physiological responses of limpet prey to a seastar
           predator and their transmission to basal trophic levels
    • Abstract: Besides the well documented behavioral changes induced by predators on prey, the predator‐induced stress can also include a suite of biochemical, neurological and metabolic changes that may represent important energetic costs and have long‐lasting effects on individuals and on the demography of prey populations. The rapid transmission of prey behavioral changes to lower trophic levels, usually associated to alteration of feeding rates, can substantially change and even reverse direction over the long term as prey cope with the energetic costs associated to predation‐induced stress. It is therefore critical to evaluate different aspects and assess the costs of non‐consumptive predator effects on prey. We investigated the behavioral and physiological responses of an herbivorous limpet, Fissurella limbata, to the presence of chemical cues and direct non‐lethal contact by the common seastar predator, Heliaster helianthus. We also evaluated whether the limpets feeding behavior was modified by the predator and whether this translated into positive or negative effects on biomass of the green alga, Ulva sp. Our experimental results show the presence of Heliaster led to increased movement activity, increased distances travelled, changes in time budget over different environmental conditions, and increased feeding rate in the keyhole limpets. Moreover, additional experiments showed that, beyond the increased metabolic rate associated to limpet increased activity, predator chemical cues heighten metabolic rate as part of the induced stress response. Changes in individual movement and displacement distances observed through the 9d experiment can be interpreted as part of the escape response exhibited by limpets to reduce the risk of being captured by the predator. Increased limpet feeding rate on algae can be visualized as a way individuals compensate for the elevated energetic costs of movement and heightened metabolic rates produced by the predator‐induced stress, which can leads to negative effects on abundance of the lower trophic level. This article is protected by copyright. All rights reserved.
  • A critical examination of indices of dynamic interaction for wildlife
           telemetry studies
    • Abstract: Wildlife scientists continue to be interested in studying ways to quantify how the movements of animals are inter‐dependent – dynamic interaction. While a number of applied studies of dynamic interaction exist, little is known about the comparative effectiveness and applicability of available methods used for quantifying interactions among animals. We highlight the formulation, implementation, and interpretation of a suite of eight currently available indices of dynamic interaction. Point‐ and path‐based approaches are contrasted to demonstrate differences between methods and underlying assumptions on telemetry data. Correlated and biased‐correlated random walks were simulated at a range of sampling resolutions to generate scenarios with dynamic interaction present and absent. We evaluate the effectiveness of each index at identifying differing types of interactive behaviour at each sampling resolution. Each index is then applied to an empirical telemetry dataset of three white‐tailed deer (Odocoileus virginianus) dyads. Results from the simulated data show that three indices of dynamic interaction reliant on statistical testing procedures are susceptible to Type I error, which increases at fine sampling resolutions. In the white‐tailed deer examples, a recently developed index for quantifying local‐level cohesive movement behaviour (the di index) provides revealing information on the presence of infrequent and varying interactions in space and time. Point‐based approaches implemented with finely sampled telemetry data over‐estimate the presence of interactions (Type I errors). Indices producing only a single global statistic (7 of the 8 indices) are unable to quantify infrequent and varying interactions through time. The quantification of infrequent and variable interactive behaviour has important implications for the spread of disease, and the prevalence of social behaviour in wildlife. Guidelines are presented to inform researchers wishing to study dynamic interaction patterns in their own telemetry datasets. Finally, we make openly available our code, in the statistical software R, for computing each index of dynamic interaction presented herein. This article is protected by copyright. All rights reserved.
  • Large‐scale movements in European badgers: has the tail of the
           movement kernel been underestimated'
    • Abstract: Characterising patterns of animal movement is a major aim in population ecology, and yet doing so at an appropriate spatial‐scale remains a major challenge. Estimating the frequency and distances of movements are of particular importance when species are implicated in the transmission of zoonotic diseases. European badgers (Meles meles) are classically viewed as exhibiting limited dispersal, and yet their movements bring them into conflict with farmers due to their potential to spread bovine tuberculosis in parts of their range. Considerable uncertainty surrounds the movement potential of badgers, and this may be related to the spatial‐scale of previous empirical studies. We conducted a large‐scale mark‐recapture study on badgers (755km2; 2008‐2012; 1,935 capture‐events; 963 badgers) to investigate movement patterns in badgers, and undertook a comparative meta‐analysis using published data from 15 European populations. The dispersal movement (>1km) kernel followed an inverse power‐law function, with a substantial ‘tail’ indicating the occurrence of rare long‐distance dispersal attempts during the study period. The mean recorded distance from this distribution was 2.6km., the upper 95%ile was 7.3km and the longest recorded was 22.1km. Dispersal frequency distributions were significantly different between genders; males dispersed more frequently than females but females made proportionally more long‐distance dispersal attempts than males. We used a subsampling approach to demonstrate that the appropriate minimum spatial‐scale to characterise badger movements in our study population was 80km2, substantially larger than many previous badger studies. Furthermore, the meta‐analysis indicated a significant association between maximum movement distance and study area size, while controlling for population density. Maximum long‐distance movements were often only recorded by chance beyond the boundaries of study areas. These findings suggest that the tail of the badger movement distribution is currently underestimated. The implications of this for understanding the spatial‐ecology of badger populations and for the design of disease intervention strategies are potentially significant. This article is protected by copyright. All rights reserved.
  • Night warming on hot days produces novel impacts on development, survival
           and reproduction in a small arthropod
    • Abstract: An asymmetric increase of nighttime temperatures on hot days is one of the main features of global climate change. But the biological effects of an increased nighttime temperature combined with high daytime temperature are unclear. We used six thermal regimens to simulate nighttime temperatures on hot days and investigated the effects of night warming on life history traits of the English grain aphid Sitobion avenae. Experimental temperatures fluctuated in continuous diurnal cycles, increasing from 27 °C to a maximum 35 °C and then declining to 27 °C gradually before further dropping to different minima (13, 16, 19, 21, 23 or 25 °C) representing nighttime temperatures. When compared to expectations based on constant temperatures, night warming raised the optimum temperature for development by 3 °C, in contrast to results from experiments where temperature variability was altered symmetrically or in a parallel manner. Night warming also reduced aphid survival under heat from 75% to 37%, and depressed adult performance by up to 50%. Overall, night warming exacerbated the detrimental effects of hot days on the intrinsic rate of population increase, which was predicted to drop by 30% when nighttime minimum temperatures exceeded 20 °C. Our novel findings on development challenge the ‘Kaufmann effect’, suggesting this is inapplicable to night warming likely to be encountered in nature. Although many average temperature models predict increasing pest outbreaks, our results suggest that outbreaks of some species might decrease due to the effects of night warming on population dynamics. This article is protected by copyright. All rights reserved.
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