Evolution and behavioural responses to human-induced rapid environmental change

Using accelerometers to remotely and automatically characterize behavior in small animals

Activity budgets in wild animals are challenging to measure via direct observation because data collection is time consuming and observer effects are potentially confounding. Although tri-axial accelerometers are increasingly employed for this purpose, their application in small-bodied animals has been limited by weight restrictions. Additionally, accelerometers engender novel complications, as a system is needed to reliably map acceleration to behaviors. In this study, we describe newly developed, tiny acceleration-logging devices (1.5-2.5 g) and use them to characterize behavior in two chipmunk species. We collected paired accelerometer readings and behavioral observations from captive individuals. We then employed techniques from machine learning to develop an automatic system for coding accelerometer readings into behavioral categories. Finally, we deployed and recovered accelerometers from free-living, wild chipmunks. This is the first time to our knowledge that accelerometers have been used to generate behavioral data for small-bodied (<100 g), free-living mammals.

Stress in the neighborhood: Tissue glucocorticoids relative to stream quality for five species of fish

Anthropogenic alterations to terrestrial habitat (e.g., urbanization, deforestation, agriculture) can have a variety of negative effects on watercourses that flow through disturbed landscapes. Currently, the relationship between stream habitat quality and fish condition remains poorly understood. The use of physiological metrics such as glucocorticoids (GCs) provides a useful tool for quantifying these effects by relating the health of resident fishes to stream quality. To date, however, most studies that measure GC levels tend to focus on a single, large-bodied species, rather than evaluating how GCs may be influenced differently between species in a community. In this study, we measured cortisol, the glucocorticoid found in fishes, from fish tissues to quantify effects of habitat degradation on the glucocorticoid function of five species of juvenile and small-bodied stream fish which differ ecologically and phylogenetically. Largemouth bass Micropterus salmoides, brown bullhead Ameiurus nebulosus, white sucker Catostomus commersonii, pumpkinseed Lepomis gibbosus, and logperch Percina caprodes were sampled from a reference and a degraded stream. Upon capture, fish were either euthanized immediately, to quantify baseline stress parameters, or following a standardized stressor, to quantify GC responsiveness. As a result of stream degradation largemouth bass possessed altered baseline GC concentrations and brown bullhead and logperch had altered GC responses to a stressor. White sucker and pumpkinseed did not demonstrate any alteration in baseline or post-stress GC concentrations. Together, our results show that different species residing in identical habitats can demonstrate a variety of responses to environmental stress, highlighting the variation in physiological ability to cope under poor environmental conditions, as well as the difficulty of predicting GC dynamics in wild animals. Understanding the relationships between GC function, habitat quality, and population-level processes will increase the ability of researchers and managers to predict how fish communities and aquatic ecosystems will be shaped by anthropogenic environmental change.

Low levels of chemical anthropogenic pollution may threaten amphibians by impairing predator recognition

Recent studies suggest that direct mortality and physiological effects caused by pollutants are major contributing factors to global amphibian decline. However, even sublethal concentrations of pollutants could be harmful if they combined with other factors to cause high mortality in amphibians. Here we show that sublethal concentrations of pollutants can disrupt the ability of amphibian larvae to recognize predators, hence increasing their risk of predation. This effect is indeed much more important since very low amounts of pollutants are ubiquitous, and environmental efforts are mostly directed towards preventing lethal spills. We analyzed the effects of two common contaminants (humic acid and ammonium nitrate) on the ability of tadpoles of the western spadefoot toad (Pelobates cultripes) to recognize chemical cues from a common predator, nymphs of the dragonfly Anax imperator. We compared the swimming activity of tadpoles in the presence and absence of water-borne chemical cues from dragonflies at different concentrations of humic acid and ammonium nitrate. Tadpoles reduced swimming activity in response to predator cues in the absence of pollutants, whereas they remained unresponsive to these cues when either humic acid or ammonium nitrate was added to the water, even at low concentrations. Moreover, changes in tadpole activity associated with the pollutants themselves were non-significant, indicating no toxic effect. Alteration of the natural chemical environment of aquatic systems by pollutants may be an important contributing cause for declines in amphibian populations, even at sublethal concentrations.

Conservation physiology of animal migration

Migration is a widespread phenomenon among many taxa. This complex behaviour enables animals to exploit many temporally productive and spatially discrete habitats to accrue various fitness benefits (e.g. growth, reproduction, predator avoidance). Human activities and global environmental change represent potential threats to migrating animals (from individuals to species), and research is underway to understand mechanisms that control migration and how migration responds to modern challenges. Focusing on behavioural and physiological aspects of migration can help to provide better understanding, management and conservation of migratory populations. Here, we highlight different physiological, behavioural and biomechanical aspects of animal migration that will help us to understand how migratory animals interact with current and future anthropogenic threats. We are in the early stages of a changing planet, and our understanding of how physiology is linked to the persistence of migratory animals is still developing; therefore, we regard the following questions as being central to the conservation physiology of animal migrations. Will climate change influence the energetic costs of migration? Will shifting temperatures change the annual clocks of migrating animals? Will anthropogenic influences have an effect on orientation during migration? Will increased anthropogenic alteration of migration stopover sites/migration corridors affect the stress physiology of migrating animals? Can physiological knowledge be used to identify strategies for facilitating the movement of animals? Our synthesis reveals that given the inherent challenges of migration, additional stressors derived from altered environments (e.g. climate change, physical habitat alteration, light pollution) or interaction with human infrastructure (e.g. wind or hydrokinetic turbines, dams) or activities (e.g. fisheries) could lead to long-term changes to migratory phenotypes. However, uncertainty remains because of the complexity of biological systems, the inherently dynamic nature of the environment and the scale at which many migrations occur and associated threats operate, necessitating improved integration of physiological approaches to the conservation of migratory animals.

Small Variations in Early-Life Environment Can Affect Coping Behaviour in Response to Foraging Challenge in the Three-Spined Stickleback

CONTEXT

An increasing concern in the face of human expansion throughout natural habitats is whether animal populations can respond adaptively when confronted with challenges like environmental change and novelty. Behavioural flexibility is an important factor in estimating the adaptive potential of both individuals and populations, and predicting the degree to which they can cope with change.

STUDY DESIGN

This study on the three-spined stickleback (Gasterosteus aculeatus) is an empiric illustration of the degree of behavioural variation that can emerge between semi-natural systems within only a single generation. Wild-caught adult sticklebacks (P, N = 400) were randomly distributed in equal densities over 20 standardized semi-natural environments (ponds), and one year later offspring (F1, N = 652) were presented with repeated behavioural assays. Individuals were challenged to reach a food source through a novel transparent obstacle, during which exploration, activity, foraging, sociability and wall-biting behaviours were recorded through video observation. We found that coping responses of individuals from the first generation to this unfamiliar foraging challenge were related to even relatively small, naturally diversified variation in developmental environment. All measured behaviours were correlated with each other. Especially exploration, sociability and wall-biting were found to differ significantly between ponds. These differences could not be explained by stickleback density or the turbidity of the water.

FINDINGS

Our findings show that a) differences in early-life environment appear to affect stickleback feeding behaviour later in life; b) this is the case even when the environmental differences are only small, within natural parameters and diversified gradually; and c) effects are present despite semi-natural conditions that fluctuate during the year. Therefore, in behaviourally plastic animals like the stickleback, the adaptive response to human-induced habitat disturbance may occur rapidly (within one generation) and vary strongly based on the system's (starting) conditions. This has important implications for the variability in animal behaviour, which may be much larger than expected from studying laboratory systems, as well as for the validity of predictions of population responses to change.

The road to opportunities: landscape change promotes body-size divergence in a highly mobile species

Landscape change provides a suitable framework for investigating population-level responses to novel ecological pressures. However, relatively little attention has been paid to examine the potential influence of landscape change on the geographic scale of population differentiation. Here, we tested for morphological differentiation of red-necked nightjars Caprimulgus ruficollis breeding in a managed property and a natural reserve situated less than 10 km apart. At both sites, we also estimated site fidelity over 5 years and quantified the potential foraging opportunities for nightjars. Breeding birds in the managed habitat were significantly larger in size—as indexed by keel length—than those in the natural one. However, there were no significant differences in wing or tail length. Immigration from neighboring areas was almost negligible and, furthermore, no individual (out of 1130 captures overall) exchanged habitats between years, indicating strong site fidelity. Food supply for nightjars was equally abundant in both habitats, but the availability of foraging sites was remarkably higher in the managed property. As a result, nightjars—particularly fledglings—in the latter habitat benefited from increased foraging opportunities in relation to those in the natural site. It seems likely that the fine-scale variation in nightjar morphology reflects a phenotypic response to unequal local conditions, since non-random dispersal or differential mortality had been determined not to be influential. High site fidelity appears to contribute to the maintenance of body-size differences between the two habitats. Results from this nightjar population highlight the potential of human-induced landscape change to promote population-level responses at exceedingly small geographic scales.

Differences in tolerance to anthropogenic stress between invasive and native bivalves

Tolerance towards environmental stress has been frequently considered as one of the key determinants of invasion success. However, empirical evidence supporting the assumption that invasive species can better endure unfavorable conditions compared with native species is limited and has yielded opposing results. In this study, we examined the tolerance to different stress conditions (thermal stress and trace metal zinc pollution stress) in two phylogenetically related and functionally similar freshwater bivalve species, the native Anodonta anatina and the invasive Sinanodonta woodiana. We assessed potential differences in response to stress conditions using several cellular response assays: efficiency of the multixenobiotic resistance mechanism, respiration estimate (INT reduction capacity), and enzymatic biomarkers. Our results demonstrated that the invasive species overall coped much better with unfavorable conditions. The higher tolerance of S. woodiana was evident from (i) significantly decreased Rhodamine B accumulation indicating more efficient multixenobiotic resistance mechanism; (ii) significantly higher INT reduction capacity and (iii) less pronounced alterations in the activity of stress-related enzymes (glutathione-S-transferase, catalase) and of a neurotoxicity biomarker (cholinesterase) in the majority of treatment conditions in both stress trials. Higher tolerance to thermal extremes may provide physiological benefit for further invasion success of S. woodiana in European freshwaters, especially in the context of climate change.

Adapting to Adaptations: Behavioural Strategies that are Robust to Mutations and Other Organisational-Transformations

Genetic mutations, infection by parasites or symbionts, and other events can transform the way that an organism’s internal state changes in response to a given environment. We use a minimalistic computational model to support an argument that by behaving “interoceptively,” i.e. responding to internal state rather than to the environment, organisms can be robust to these organisational-transformations. We suggest that the robustness of interoceptive behaviour is due, in part, to the asymmetrical relationship between an organism and its environment, where the latter more substantially influences the former than vice versa. This relationship means that interoceptive behaviour can respond to the environment, the internal state and the interaction between the two, while exteroceptive behaviour can only respond to the environment. We discuss the possibilities that (i) interoceptive behaviour may play an important role of facilitating adaptive evolution (especially in the early evolution of primitive life) and (ii) interoceptive mechanisms could prove useful in efforts to create more robust synthetic life-forms.

The role of non-genetic inheritance in evolutionary rescue: epigenetic buffering, heritable bet hedging and epigenetic traps

Rapid environmental change is predicted to compromise population survival, and the resulting strong selective pressure can erode genetic variation, making evolutionary rescue unlikely. Non-genetic inheritance may provide a solution to this problem and help explain the current lack of fit between purely genetic evolutionary models and empirical data. We hypothesize that epigenetic modifications can facilitate evolutionary rescue through 'epigenetic buffering'. By facilitating the inheritance of novel phenotypic variants that are generated by environmental change-a strategy we call 'heritable bet hedging'-epigenetic modifications could maintain and increase the evolutionary potential of a population. This process may facilitate genetic adaptation by preserving existing genetic variation, releasing cryptic genetic variation and/or facilitating mutations in functional loci. Although we show that examples of non-genetic inheritance are often maladaptive in the short term, accounting for phenotypic variance and non-adaptive plasticity may reveal important evolutionary implications over longer time scales. We also discuss the possibility that maladaptive epigenetic responses may be due to 'epigenetic traps', whereby evolutionarily novel factors (e.g. endocrine disruptors) hack into the existing epigenetic machinery. We stress that more ecologically relevant work on transgenerational epigenetic inheritance is required. Researchers conducting studies on transgenerational environmental effects should report measures of phenotypic variance, so that the possibility of both bet hedging and heritable bet hedging can be assessed. Future empirical and theoretical work is required to assess the relative importance of genetic and epigenetic variation, and their interaction, for evolutionary rescue.

Evolution and Phylogenetic Diversity of Yam Species (Dioscorea spp.): Implication for Conservation and Agricultural Practices

Yams (Dioscorea spp.) consist of approximately 600 species. Presently, these species are threatened by genetic erosion due to many factors such as pest attacks and farming practices. In parallel, complex taxonomic boundaries in this genus makes it more challenging to properly address the genetic diversity of yam and manage its germplasm. As a first step toward evaluating and preserving the genetic diversity yam species, we use a phylogenetic diversity (PD) approach that has the advantage to investigate phylogenetic relationships and test hypotheses of species monophyly while alleviating to the problem of ploidy variation within and among species. The Bayesian phylogenetic analysis of 62 accessions from 7 species from three regions of Cameroon showed that most Dioscorea sections were monophyletic, but species within sections were generally non-monophyletic. The wild species D. praehensilis and cultivated D. cayenensis were the species with the highest PD. At the opposite, D. esculenta has a low PD and future studies should focus on this species to properly address its conservation status. We also show that wild species show a stronger genetic structure than cultivated species, which potentially reflects the management of the yam germplasm by farmers. These findings show that phylogenetic diversity is a promising approach for an initial investigation of genetic diversity in a crop consisting of closely related species.

Is supplementary feeding in gardens a driver of evolutionary change in a migratory bird species?

Human activities are causing rapid environmental change at a global scale. Urbanization is responsible for some of the most extreme human-altered habitats and is a known driver of evolutionary change, but evidence and understanding of these processes is limited. Here, we investigate the potential underlying mechanisms contributing to the contemporary evolution of migration behaviour in the Eurasian blackcap (Sylvia atricapilla). Blackcaps from central Europe have been wintering in urban areas of Britain with increasing frequency over the past 60 years, rather than migrating south to the Mediterranean. It has been hypothesized that the popularization of providing supplementary foods for wild birds within Britain may have influenced this marked migratory change, but quantifying the selective forces shaping evolutionary changes remains challenging. Using a long-term national scale data set, we examine both the spatial distribution and interannual variation in blackcap wintering behaviour in Britain in relation to supplementary food availability and local climate. Over a 12-year period, we show that blackcaps are becoming increasingly associated with the provision of supplementary foods in British gardens, and that the reliability of bird food supplies is influencing their winter distribution at a national scale. In addition, local climatic temperatures and broader scale weather variation are also important determinants of blackcap wintering patterns once they arrive in Britain. Based on our findings, we conclude that a synergistic effect of increased availability of feeding resources, in the form of garden bird food, coupled with climatic amelioration, has enabled a successful new wintering population to become established in Britain. As global biodiversity is threatened by human-induced environmental change, this study presents new and timely evidence of the role human activities can play in shaping evolutionary trajectories.

Thermal niche predicts tolerance to habitat conversion in tropical amphibians and reptiles

Habitat conversion is a major driver of the biodiversity crisis, yet why some species undergo local extinction while others thrive under novel conditions remains unclear. We suggest that focusing on species' niches, rather than traits, may provide the predictive power needed to forecast biodiversity change. We first examine two Neotropical frog congeners with drastically different affinities to deforestation and document how thermal niche explains deforestation tolerance. The more deforestation-tolerant species is associated with warmer macroclimates across Costa Rica, and warmer microclimates within landscapes. Further, in laboratory experiments, the more deforestation-tolerant species has critical thermal limits, and a jumping performance optimum, shifted ~2 °C warmer than those of the more forest-affiliated species, corresponding to the ~3 °C difference in daytime maximum temperature that these species experience between habitats. Crucially, neither species strictly specializes on either habitat - instead habitat use is governed by regional environmental temperature. Both species track temperature along an elevational gradient, and shift their habitat use from cooler forest at lower elevations to warmer deforested pastures upslope. To generalize these conclusions, we expand our analysis to the entire mid-elevational herpetological community of southern Costa Rica. We assess the climatological affinities of 33 amphibian and reptile species, showing that across both taxonomic classes, thermal niche predicts presence in deforested habitat as well as or better than many commonly used traits. These data suggest that warm-adapted species carry a significant survival advantage amidst the synergistic impacts of land-use conversion and climate change.

Turtles outsmart rapid environmental change: The role of cognition in navigation

Animals inhabiting changing environments show high levels of cognitive plasticity. Cognition may be a means by which animals buffer the impact of environmental change. However, studies examining the evolution of cognition seldom compare populations where change is rapid and selection pressures are strong. We investigated this phenomenon by radiotracking experienced and naïve Eastern painted turtles (Chrysemys picta) as they sought new habitats when their pond was drained. Resident adults repeatedly used specific routes to permanent water sources with exceptional precision, while adults translocated to the site did not. Naïve 1-3 y olds from both populations used the paths taken by resident adults, an ability lost by age 4. Experience did not, however, influence the timing of movement or the latency to begin navigation. This suggests that learning during a critical period may be important for how animals respond to changing environments, highlighting the importance of incorporating cognition into conservation.

Developmental plasticity in vision and behavior may help guppies overcome increased turbidity

Increasing turbidity in streams and rivers near human activity is cause for environmental concern, as the ability of aquatic organisms to use visual information declines. To investigate how some organisms might be able to developmentally compensate for increasing turbidity, we reared guppies (Poecilia reticulata) in either clear or turbid water. We assessed the effects of developmental treatments on adult behavior and aspects of the visual system by testing fish from both developmental treatments in turbid and clear water. We found a strong interactive effect of rearing and assay conditions: fish reared in clear water tended to decrease activity in turbid water, whereas fish reared in turbid water tended to increase activity in turbid water. Guppies from all treatments decreased activity when exposed to a predator. To measure plasticity in the visual system, we quantified treatment differences in opsin gene expression of individuals. We detected a shift from mid-wave-sensitive opsins to long wave-sensitive opsins for guppies reared in turbid water. Since long-wavelength sensitivity is important in motion detection, this shift likely allows guppies to salvage motion-detecting abilities when visual information is obscured in turbid water. Our results demonstrate the importance of developmental plasticity in responses of organisms to rapidly changing environments.

Here today, gone tomorrow: Short-term retention of pesticide-induced tolerance in amphibians

Pesticide use has led to the ubiquitous contamination of natural habitats, which has inadvertently increased pesticide tolerance in target and nontarget species. Historically, increased pesticide tolerance has been attributed to natural selection for tolerance among individuals of affected populations. Recent research, however, has discovered that pesticide tolerance can be increased through phenotypic plasticity. Although induced pesticide tolerance may benefit organisms experiencing contaminated systems, little is known about its occurrence in vertebrates, its retention through ontogeny, or potential life history tradeoffs. Using time-to-death assays at 2 distinct developmental windows, the authors discovered that gray treefrog (Hyla versicolor) tadpoles exposed to sublethal concentrations (0 mg a.i./L, 0.5 mg a.i./L, and 1.0 mg a.i./L) of the insecticide Sevin® (carbaryl) early in life increased their pesticide tolerance to a lethal carbaryl concentration 5 d after sublethal exposure. However, this increased tolerance was not retained later in ontogeny (23 d post-sublethal exposure). Moreover, no indication was found of pesticide-induced treefrogs experiencing life-history tradeoffs in terms of survival to metamorphosis, mass, or snout-vent length. Gray treefrogs are only the second vertebrate species and the second amphibian family to exhibit pesticide-induced tolerance after sublethal exposure. The authors' data suggest that the ability to induce increased pesticide tolerance may play a critical role in amphibian survival in contaminated ecosystems. However, future work is needed to test the occurrence of inducible pesticide tolerance among numerous amphibian populations worldwide.

Among-year variation in the repeatability, within- and between-individual, and phenotypic correlations of behaviors in a natural population

When mean behaviors correlate among individuals, they form behavioral syndromes. One way to understand the evolution of such a group-level phenomenon is to compare horizontally patterns of correlations among populations (or species) or follow longitudinally the same population over years in the light of parallel differences in the environment. We applied the longitudinal approach to 8-year field data and analyzed phenotypic correlations, and their within- and between-individual components, among three behaviors (novelty avoidance, aggression, and risk-taking) in male collared flycatchers, Ficedula albicollis, in a meta-analytic framework. The phenotypic correlation between novelty avoidance and aggression varied heterogeneously (it was positive in some years, while it was negative in other years), while the other pair-wise correlations were consistently positive over the study period. We investigated four potential socio-ecological factors, and found evidence that the among-year alterations in the demographic structure of the population (density, age composition) can be responsible for the heterogeneous effect sizes. Comparing within- and between-individual correlations across pairs of traits, we found that the correlation between aggression and risk-taking at the among-individual level was the strongest suggesting that this relationship has the highest potential to form a behavioral syndrome. Within-year repeatabilities varied among traits, but were systematically higher than between-year repeatabilities. Our study highlights on an empirical basis that there can be several biological and statistical reasons behind detecting a phenotypic correlation in a study, but only few of these imply that fixed behavioral syndromes are maintained in a natural population. In fact, some correlations seem to be shaped by environmental fluctuations.

Predation Risk Perception, Food Density and Conspecific Cues Shape Foraging Decisions in a Tropical Lizard

When foraging, animals can maximize their fitness if they are able to tailor their foraging decisions to current environmental conditions. When making foraging decisions, individuals need to assess the benefits of foraging while accounting for the potential risks of being captured by a predator. However, whether and how different factors interact to shape these decisions is not yet well understood, especially in individual foragers. Here we present a standardized set of manipulative field experiments in the form of foraging assays in the tropical lizard Anolis cristatellus in Puerto Rico. We presented male lizards with foraging opportunities to test how the presence of conspecifics, predation-risk perception, the abundance of food, and interactions among these factors determines the outcome of foraging decisions. In Experiment 1, anoles foraged faster when food was scarce and other conspecifics were present near the feeding tray, while they took longer to feed when food was abundant and when no conspecifics were present. These results suggest that foraging decisions in anoles are the result of a complex process in which individuals assess predation risk by using information from conspecific individuals while taking into account food abundance. In Experiment 2, a simulated increase in predation risk (i.e., distance to the feeding tray) confirmed the relevance of risk perception by showing that the use of available perches is strongly correlated with the latency to feed. We found Puerto Rican crested anoles integrate instantaneous ecological information about food abundance, conspecific activity and predation risk, and adjust their foraging behavior accordingly.

Evolutionary Influences of Plastic Behavioral Responses Upon Environmental Challenges in an Adaptive Radiation

At the end of the 19th century, the suggestion was made by several scientists, including J. M. Baldwin, that behavioral responses to environmental change could both rescue populations from extinction (Baldwin Effect) and influence the course of subsequent evolution. Here we provide the historical and theoretical background for this argument and offer evidence of the importance of these ideas for understanding how animals (and other organisms that exhibit behavior) will respond to the rapid environmental changes caused by human activity. We offer examples from long-term research on the evolution of behavioral and other phenotypes in the adaptive radiation of the threespine stickleback fish (Gasterosteus aculeatus), a radiation in which it is possible to infer ancestral patterns of behavioral plasticity relative to the post-glacial freshwater radiation in northwestern North America, and to use patterns of parallelism and contemporary evolution to understand adaptive causes of responses to environmental modification. Our work offers insights into the complexity of cognitive responses to environmental change, and into the importance of examining multiple aspects of the phenotype simultaneously, if we are to understand how behavioral shifts contribute to the persistence of populations and to subsequent evolution. We conclude by discussing the origins of apparent novelties induced by environmental shifts, and the importance of accounting for geographic variation within species if we are to accurately anticipate the effects of anthropogenic environmental modification on the persistence and evolution of animals.

The evolution of antipredator behaviour following relaxed and reversed selection in Alaskan threespine stickleback fish

Changing environments, whether through natural or anthropogenic causes, can lead to the loss of some selective pressures ('relaxed selection') and possibly even the reinstatement of selective agents not encountered for many generations ('reversed selection'). We examined the outcome of relaxed and reversed selection in the adaptive radiation of the threespine stickleback fish, Gasterostues aculeatus L., in which isolated populations encounter a variety of predation regimes. Oceanic stickleback, which represent the ancestral founders of the freshwater radiation, encounter many piscivorous fish. Derived, freshwater populations, on the other hand, vary with respect to the presence of predators. Some populations encounter native salmonids, whereas others have not experienced predation by large fish in thousands of generations (relax-selected populations). Some relax-selected populations have had sport fish, including rainbow trout, Oncorhynchus mykiss, introduced within the past several decades (reverse-selected). We examined the behavioural responses of stickleback from three populations of each type to simulated attacks by trout and birds to determine whether relaxed and reversed selection has led to divergence in behaviour, and whether this divergence was predator specific. Fish from trout-free populations showed weak responses to trout, as predicted, but these responses were similar to those of oceanic (ancestral) populations. Fish from populations that co-occur with trout, whether native or introduced, showed elevated antipredator responses, indicating that in freshwater, trout predation selects for enhanced antipredator responses, which can evolve extremely rapidly. Comparison of laboratory-reared and wild-caught individuals suggests a combination of learned and genetic components to this variation. Responses to a model bird flyover were weakly linked to predation environment, indicating that the loss of predation by trout may partially influence the evolution of responses to birds. Our results reject the hypothesis that the consistent presence of predatory birds has been sufficient to maintain responses to piscivorous fish under periods of relaxed selection.

Anthropogenic ecosystem fragmentation drives shared and unique patterns of sexual signal divergence among three species of Bahamian mosquitofish

When confronted with similar environmental challenges, different organisms can exhibit dissimilar phenotypic responses. Therefore, understanding patterns of phenotypic divergence for closely related species requires considering distinct evolutionary histories. Here, we investigated how a common form of human-induced environmental alteration, habitat fragmentation, may drive phenotypic divergence among three closely related species of Bahamian mosquitofish (Gambusia spp.). Focusing on one phenotypic trait (male coloration), having a priori predictions of divergence, we tested whether populations persisting in fragmented habitats differed from those inhabiting unfragmented habitats and examined the consistency of the pattern across species. Species exhibited both shared and unique patterns of phenotypic divergence between the two types of habitats, with shared patterns representing the stronger effect. For all species, populations in fragmented habitats had fewer dorsal-fin spots. In contrast, the magnitude and trajectory of divergence in dorsal-fin color, a sexually selected trait, differed among species. We identified fragmentation-mediated increased turbidity as a possible driver of these trait shifts. These results suggest that even closely related species can exhibit diverse phenotypic responses when encountering similar human-mediated selection regimes. This element of unpredictability complicates forecasting the phenotypic responses of wild organisms faced with anthropogenic change – an important component of biological conservation and ecosystem management.

A framework to assess evolutionary responses to anthropogenic light and sound

Human activities have caused a near-ubiquitous and evolutionarily-unprecedented increase in environmental sound levels and artificial night lighting. These stimuli reorganize communities by interfering with species-specific perception of time-cues, habitat features, and auditory and visual signals. Rapid evolutionary changes could occur in response to light and noise, given their magnitude, geographical extent, and degree to which they represent unprecedented environmental conditions. We present a framework for investigating anthropogenic light and noise as agents of selection, and as drivers of other evolutionary processes, to influence a range of behavioral and physiological traits such as phenological characters and sensory and signaling systems. In this context, opportunities abound for understanding contemporary and rapid evolution in response to human-caused environmental change.

Thinking about Change: An Integrative Approach for Examining Cognition in a Changing World

We are currently experiencing shifts in climate at rates not previously recorded. One important aspect of this change is a tendency toward extremes--extremes in temperature and moisture, both within and among years. Numerous studies focus on the physiological consequences of environmental change, especially in terms of ectothermic taxa's thermal regime and use of habitat. For many species, though, cognitive responses may be a means of response to environmental perturbation. However, the effects of environmental change on the general mechanisms of cognitive processes and their implications for larger phenomena are seldom examined. Moreover, at a larger scale, we do not fully understand the features of the environment that might select for cognitive enhancements or their mechanisms, making us unable to accurately predict which species might experience the most severe response to environmental change and in which environments. This symposium brought together scientists from numerous disciplines to examine the role of cognition in how organisms cope with changing environments. We cover topics from the perspectives of the physiological mechanisms underlying and driving cognition to the complexity of individual behavioral responses in changing environments to emergent large-scale processes influencing species' abilities to respond to such change. Our ultimate goals are to explore how animals use cognition to cope with rapid environmental change, how such coping mechanisms "scale up" to affect ecological and evolutionary patterns, and how we might determine which features of the environment have been (and will become) most important for the conservation of biodiversity.

Integrating animal personality into insect population and community ecology

Despite the recent surge of interest in the concept of animal personalities, that is, temporally consistent individual differences in behavior, few studies have integrated intraspecific behavioral variation in population or community ecology. Insects and other arthropods provide ideal model systems to study how intraspecific behavioral variation affects phenomena in ecology. This is due to the fact that arthropods not only are highly amenable to experimental manipulation, but they also allow us to answer general ecological questions on multiple scales of biological organization. Herein, we review recent developments and views on how the framework of animal personality could provide a deeper understanding of classic issues in (1) population ecology (e.g., local adaptation, dispersal, and invasion), (2) community ecology (e.g., food webs and ecosystem engineering), and (3) more insect-focused topics such as metamorphosis and pollination biology.

Linking anthropogenic resources to wildlife-pathogen dynamics: a review and meta-analysis

Urbanisation and agriculture cause declines for many wildlife, but some species benefit from novel resources, especially food, provided in human-dominated habitats. Resulting shifts in wildlife ecology can alter infectious disease dynamics and create opportunities for cross-species transmission, yet predicting host-pathogen responses to resource provisioning is challenging. Factors enhancing transmission, such as increased aggregation, could be offset by better host immunity due to improved nutrition. Here, we conduct a review and meta-analysis to show that food provisioning results in highly heterogeneous infection outcomes that depend on pathogen type and anthropogenic food source. We also find empirical support for behavioural and immune mechanisms through which human-provided resources alter host exposure and tolerance to pathogens. A review of recent theoretical models of resource provisioning and infection dynamics shows that changes in host contact rates and immunity produce strong non-linear responses in pathogen invasion and prevalence. By integrating results of our meta-analysis back into a theoretical framework, we find provisioning amplifies pathogen invasion under increased host aggregation and tolerance, but reduces transmission if provisioned food decreases dietary exposure to parasites. These results carry implications for wildlife disease management and highlight areas for future work, such as how resource shifts might affect virulence evolution.

Apes in the Anthropocene: flexibility and survival

We are in a new epoch, the Anthropocene, and research into our closest living relatives, the great apes, must keep pace with the rate that our species is driving change. While a goal of many studies is to understand how great apes behave in natural contexts, the impact of human activities must increasingly be taken into account. This is both a challenge and an opportunity, which can importantly inform research in three diverse fields: cognition, human evolution, and conservation. No long-term great ape research site is wholly unaffected by human influence, but research at those that are especially affected by human activity is particularly important for ensuring that our great ape kin survive the Anthropocene.

Opposite selection on behavioural types by active and passive fishing gears in a simulated guppy Poecilia reticulata fishery

This study assessed whether fishing gear was selective on behavioural traits, such as boldness and activity, and how this was related with a productivity trait, growth. Female guppies Poecilia reticulata were screened for their behaviour on the shy-bold axis and activity, and then tested whether they were captured differently by passive and active fishing gear, here represented by a trap and a trawl. Both gears were selective on boldness; bold individuals were caught faster by the trap, but escaped the trawl more often. Boldness and gear vulnerability showed weak correlations with activity and growth. The results draw attention to the importance of the behavioural dimension of fishing: selective fishing on behavioural traits will change the trait composition of the population, and might eventually affect resilience and fishery productivity.

Anthropogenic host plant expansion leads a nettle-feeding butterfly out of the forest: consequences for larval survival and developmental plasticity in adult morphology

Recent anthropogenic eutrophication has meant that host plants of nettle-feeding insects became quasi-omnipresent in fertile regions of Western Europe. However, host plant resource quality – in terms of microclimate and nutritional value – may vary considerably between the ‘original’ forest habitat and ‘recent’ agricultural habitat. Here, we compared development in both environmental settings using a split-brood design, so as to explore to what extent larval survival and adult morphology in the nettle-feeding butterfly Aglais urticae are influenced by the anthropogenic environment. Nettles along field margins had higher C/N ratios and provided warmer microclimates to larvae. Larvae developed 20% faster and tended to improve their survival rates, on the agricultural land compared to woodland. Our split-brood approach indicated plastic responses within families, but also family effects in the phenotypic responses. Adult males and females had darker wing pigmentation in the drier and warmer agricultural environment, which contrasts with the thermal melanism hypothesis. Developmental plasticity in response to this microclimatically different and more variable habitat was associated with a broader phenotypic parameter space for the species. Both habitat expansion and developmental plasticity are likely contributors to the ecological and evolutionary success of these nettle-feeding insects in anthropogenic environments under high nitrogen load.

Individual variation in anthropogenic resource use in an urban carnivore

With increasing urbanization, some animals are adapting to human-dominated systems, offering unique opportunities to study individual adaptation to novel environments. One hypothesis for why some wildlife succeed in urban areas is that they are subsidized with anthropogenic food. Here, we combine individual-level movement patterns with diet composition based on stable isotope analysis to assess the degree to which a rapidly growing population of coyotes (Canis latrans) in Chicago consumes anthropogenic resources. We used telemetry to classify coyotes into three groups based on social class and home range composition: (1) residents with home ranges in urban nature preserves; (2) residents with home ranges that had a high proportion of urban land; and (3) transients that had relatively large home ranges and variable use of urban land. We found that natural and anthropogenic resources in this system can be reliably partitioned with carbon isotopes. Mixing models revealed that resident coyotes associated with most urban nature preserves consumed trace to minimal amounts of anthropogenic resources, while coyotes that live in the urban matrix consume moderate (30-50%) to high (>50%) proportions of anthropogenic resources. Lastly, we found evidence of prey switching between natural and anthropogenic resources and a high degree of inter-individual variation in diet among coyotes. In contrast to the expectation that urban adaptation may dampen ecological variation, our results suggest individuality in movement and diet exemplifies the successful establishment of coyotes in urban Chicago. Our study also suggests that direct anthropogenic food subsidization is not a prerequisite for successful adaptation to urban environments.

Getting ready for invasions: can background level of risk predict the ability of naïve prey to survive novel predators?

Factors predicting the outcome of predator invasions on native prey communities are critical to our understanding of invasion ecology. Here, we tested whether background level of risk affected the survival of prey to novel predators, both native and invasive, predicting that high-risk environments would better prepare prey for invasions. We used naïve woodfrog as our prey and exposed them to a high or low risk regime either as embryos (prenatal exposure) or as larvae (recent exposure). Tadpoles were then tested for their survival in the presence of 4 novel predators: two dytiscid beetles, crayfish and trout. Survival was affected by both risk level and predator type. High risk was beneficial to prey exposed to the dytiscids larvae (ambush predators), but detrimental to prey exposed to crayfish or trout (pursuit predators). No effect of ontogeny of risk was found. We further documented that high-risk tadpoles were overall more active than their low-risk counterparts, explaining the patterns found with survival. Our results provide insights into the relationship between risk and resilience to predator invasions.

Evolutionary theory as a tool for predicting extinction risk

Timely and proactive wildlife conservation requires strategies for determining which species are most at the greatest threat of extinction. Here, we suggest that evolutionary theory, particularly the concept of specialization, can be a useful tool to inform such assessments and may greatly aid in our ability to predict the vulnerabilities of species to anthropogenic impacts.

The role of age-specific learning and experience for turtles navigating a changing landscape

The severity of the environment often influences animal cognition [1-6], as does the rate of change within that environment [7-10]. Rapid alteration of habitat places limitations on basic resources such as energy, water, nesting sites, and refugia [8, 10]. How animals respond to these situations provides insight into the mechanisms of cognition and the role of behavior in adaptation [11-13]. We tested the hypothesis that learning plays a role in the navigation of the painted turtle (Chrysemys picta) within a model of environmental change. We radiotracked experienced and naive turtles at different developmental stages from two different populations as they sought out new habitats when their pond was destroyed. Our data suggest that the ability of turtles to navigate is facilitated in part by experience during a critical period. Resident adults repeatedly used specific routes with exceptional precision, while translocated adults failed to find water. Naive juveniles (1-3 years old) from both populations used the same paths taken by resident adults; the ability to follow paths was lost by age 4. We also used laboratory behavioral assays to examine the possible cues facilitating this precise navigation. Turtles responded to manipulation of the local ultraviolet environment, but not the olfactory environment. This is the first evidence to suggest that learning during a critical period may be important for how animals respond to changing environments. Our work emphasizes the need for the examination of learning in navigation and the breadth of critical learning periods across vertebrates.

Human-induced morphological shifts in an island lizard

Understanding the evolutionary consequences of anthropogenic change is an emerging topic in evolutionary biology. While highly sensitive species may go extinct in response to anthropogenic habitat alteration, those with broader environmental tolerances may persist and adapt to the changes. Here, we use morphological data from the brown anole (Anolis sagrei), a lizard species that lives in both natural and human-disturbed habitats, to examine the impact of anthropogenic habitat alteration. We find populations inhabiting disturbed habitats were significantly larger in snout-vent length, hindspan, and mass and provide evidence that the observed divergence in hindspan is driven by human-induced changes in habitat structure. Populations were found to be genetically distinct among islands but are not genetically differentiated between habitat types on islands. Thus, the observed pattern of intra-island morphological differences cannot be explained by separate founding populations. Rather, our results are consistent with morphological differences between habitats having arisen in situ on each island. Results underscore the significant impact anthropogenic change may have on evolutionary trajectories of populations that persist in human-altered habitats.

Exploring behavioral and hormonal flexibility across light environments in guppies from low-predation populations

Phenotypic flexibility is essential for organisms to respond to changing environments. Guppies experience light environments that alter their visibility to conspecifics and predators. We used guppies from populations with low rates of predation by fish, but which may be subject to avian predators, to test the hypotheses that conspicuous behaviors and the androgens that mediate them are reduced under high light, and that cortisol levels are increased under high light because the perceived risk is stressful. We found reduced courtship, potentially driven by the reduced female response to courtship, under high light. Aggression and testosterone levels were higher in the absence of females. We found elevated androgen and decreased cortisol levels following social interactions, but no relationship between hormones and behavior, and no influence of light level on hormones. We forward explanations for these results and advocate understanding the flexible response to light environments in a range of guppy populations.