Evolution and behavioural responses to human-induced rapid environmental change

Phenotypic responses to oil pollution in a poeciliid fish

Pollution damages ecosystems around the globe and some forms of pollution, like oil pollution, can be either man-made or derived from natural sources. Despite the pervasiveness of oil pollution, certain organisms are able to colonise polluted or toxic environments, yet we only have a limited understanding of how they are affected by it. Here, we analysed phenotypic responses to oil pollution in guppies (Poecilia reticulata) living in oil-polluted habitats across southern Trinidad. We analysed body-shape and life-history traits for 352 individuals from 11 independent populations, six living in oil-polluted environments (including the naturally oil-polluted Pitch Lake), and five stemming from non-polluted habitats. Based on theory of, and previous studies on, responses to environmental stressors, we predicted guppies from oil-polluted waters to have larger heads and shallower bodies, to be smaller, to invest more into reproduction, and to produce more but smaller offspring compared to guppies from non-polluted habitats. Contrary to most of our predictions, we uncovered strong population-specific variation regardless of the presence of oil pollution. Moreover, guppies from oil-polluted habitats were characterised by increased body size; rounder, deeper bodies with increased head size; and increased offspring size, when compared to their counterparts from non-polluted sites. This suggests that guppies in oil-polluted environments are not only subject to the direct negative effects of oil pollution, but might gain some (indirect) benefits from other concomitant environmental factors, such as reduced predation and reduced parasite load. Our results extend our knowledge of organismal responses to oil pollution and highlight the importance of anthropogenic pollution as a source of environmental variation. They also emphasise the understudied ecological heterogeneity of extreme environments.

Land-use change alters associations between personality and microhabitat selection

Ecologists commonly assess ecological patterns at the population level, focusing on the average response of all individuals within a population, but to predict how populations will respond to land-use change we must understand how changes to habitat differentially affect individuals within a population. For example, forest management is a widespread type of land-use that impacts wildlife through the loss of key habitat features, but individuals within a population may vary in their responses to this loss due to differences in habitat selection among individuals. Specifically, intraspecific variation in habitat selection has been linked to animal personalities (i.e., consistent behavioral differences among conspecifics), but previous research has not examined whether the relationship between personality and habitat selection is influenced by land-use change. To address this knowledge gap, we tested the hypothesis that land-use change alters the association between personality and microhabitat selection in small mammals. Specifically, we investigated two main questions: (1) To what extent are personality type and microhabitat selection correlated among conspecifics? (2) Does land-use change alter individual patterns of microhabitat selection? To answer these questions, we conducted a large-scale field experiment over 4 years, contrasting unmanaged forest (control) with managed forest (two silvicultural treatments) in Maine, USA. We examined the relationships between habitat selection and personality traits in deer mice (Peromyscus maniculatus) and southern red-backed voles (Myodes gapperi). We found that personality traits were correlated with microhabitat selection at multiple spatial scales. Furthermore, land-use change altered these patterns of selection; resulting in either the loss of personality-associated selection or in novel patterns of selection in managed forests. These findings suggest that promoting structural complexity at multiple spatial scales, such as by interspersing stands of mature forest with managed stands, may maintain a variety of intraspecific habitat selection patterns and the associated ecological outcomes.

Advantages of laboratory natural selection in the applied sciences

In the past three decades, laboratory natural selection has become a widely used technique in biological research. Most studies which have utilized this technique are in the realm of basic science, often testing hypotheses related to mechanisms of evolutionary change or ecological dynamics. While laboratory natural selection is currently utilized heavily in this setting, there is a significant gap with its usage in applied studies, especially when compared to the other selection experiment methodologies like artificial selection and directed evolution. This is despite avenues of research in the applied sciences which seem well suited to laboratory natural selection. In this review, we place laboratory natural selection in context with other selection experiments, identify the characteristics which make it well suited for particular kinds of applied research and briefly cover key examples of the usefulness of selection experiments within applied science. Finally, we identify three promising areas of inquiry for laboratory natural selection in the applied sciences: bioremediation technology, identifying mechanisms of drug resistance and optimizing biofuel production. Although laboratory natural selection is currently less utilized in applied science when compared to basic research, the method has immense promise in the field moving forward.

Habitat fragmentation induces rapid divergence of migratory and isolated sticklebacks

The adaptive capacity of many organisms is seriously challenged by human-imposed environmental change, which currently happens at unprecedented rates and magnitudes. For migratory fish, habitat fragmentation is a major challenge that can compromise their survival and reproduction. Therefore, it is important to study if fish populations can adapt to such modifications of their habitat. Here, we study whether originally anadromous three-spined stickleback populations (Gasterosteus aculeatus; “migrants”) changed in behavior and morphology in response to human-induced isolation. We made use of a natural field-experiment, where the construction of pumping stations and sluices in the 1970s unintendedly created replicates of land-locked stickleback populations (“resident”) in the Netherlands. For two years, we systematically tested populations of residents and migrants for differences in morphology and behavioral traits (activity, aggressiveness, exploration, boldness, and shoaling) in lab-based assays. We detected differences between migrant and resident populations in virtually all phenotypic traits studied: compared with the ancestral migrants, residents were smaller in size, had fewer and smaller plates and were significantly more active, aggressive, exploratory and bolder, and shoaled less. Despite large ecological differences between 2018 and 2019, results were largely consistent across the two years. Our study shows that human-induced environmental change has led to the rapid and consistent morphological and behavioral divergence of stickleback populations in about 50 generations. Such changes may be adaptive but this remains to be tested.

Enhancing the ecological realism of evolutionary mismatch theory

Following rapid environmental change, why do some animals thrive, while others struggle? We present an expanded, cue-response framework for predicting variation in behavioral responses to novel situations. We show how signal detection theory can be used when individuals have three behavioral options (approach, avoid, or ignore). Based on this theory, we outline predictions about which animals are more likely to make mistakes around novel conditions (i.e., fall for a trap or fail to use an undervalued resource) and the intensity of that mismatch (i.e., severe versus moderate). Explicitly considering three options provides a more holistic perspective and allows us to distinguish between severe and moderate traps, which could guide management strategies in a changing world.

Risk perception and tolerance shape variation in agricultural use for a transboundary elephant population

To conserve wide-ranging species in human-modified landscapes, it is essential to understand how animals selectively use or avoid cultivated areas. Use of agriculture leads to human-wildlife conflict, but evidence suggests that individuals may differ in their tendency to be involved in conflict. This is particularly relevant to wild elephant populations. We analysed GPS data of 66 free-ranging elephants in the Serengeti-Mara ecosystem to quantify their use of agriculture. We then examined factors influencing the level of agricultural use, individual change in use across years and differences in activity budgets associated with use. Using clustering methods, our data grouped into four agricultural use tactics: rare (<0.6% time in agriculture; 26% of population), sporadic (0.6%-3.8%; 34%), seasonal (3.9%-12.8%; 31%) and habitual (>12.8%; 9%). Sporadic and seasonal individuals represented two-thirds (67%) of recorded GPS fixes in agriculture, compared to 32% from habitual individuals. Increased agricultural use was associated with higher daily distance travelled and larger home range size, but not with age or sex. Individual tactic change was prevalent and the habitual tactic was maintained in consecutive years by only five elephants. Across tactics, individuals switched from diurnal to nocturnal activity during agricultural use, interpreted as representing similar risk perception of cultivated areas. Conversely, tactic choice appeared to be associated with differences in risk tolerance between individuals. Together, our results suggest that elephants are balancing the costs and benefits of crop usage at both fine (e.g. crop raid events) and long (e.g. yearly tactic change) temporal scales. The high proportion of sporadic and seasonal tactics also highlights the importance of mitigation strategies that address conflict arising from many animals, rather than targeted management of habitual crop raiders. Our approach can be applied to other species and systems to characterize individual variation in human resource use and inform mitigations for human-wildlife coexistence.

Compensating for a stressful pregnancy? Glucocorticoid treatment during gravidity reduces metabolic rate in female fence lizards post-parturition

Reproduction is a critical part of an animal's life history, but one which incurs significant costs to survival and future reproductive potential. These physiological consequences are likely to be influenced by context - for example, if an individual is subject to environmental stressors, physiological and behavioral changes associated with reproduction may be altered. Glucocorticoids, hormones produced as part of the physiological response to stressors, may alter how reproduction affects female physiology and behavior, and therefore the outcomes of reproductive trade-offs. Glucocorticoids prioritize immediate survival over reproduction, for example through changes in immune function, metabolic rate, and foraging, which may reduce energy expenditure or increase energy gain. However, we previously found that female eastern fence lizards (Sceloporus undulatus) experiencing elevated glucocorticoid levels during gestation were nevertheless able to maintain reproductive output and body condition. Here we investigate compensatory mechanisms by which eastern fence lizard females may maintain reproduction under experimental increases in a glucocorticoid, corticosterone (CORT). We found that, although CORT-treated females had similar immune function and behavior, they had reduced metabolic rates 3-5 days post-parturition compared to control females. Given that CORT-treated females spent a similar time basking and had equal food intake compared to control females, we suggest that the reduced metabolic rate is a mechanism by which CORT-treated females maintain their energy balance and reduce the energetic costs of gestation during periods of stress. This study suggests that physiological responses to reproduction may be context-dependent and could act to minimize costs of reproduction in situations where CORT is elevated (such as during periods of environmental stress).

Site fidelity and behavioral plasticity regulate an ungulate's response to extreme disturbance

With rapid global change, the frequency and severity of extreme disturbance events are increasing worldwide. The ability of animal populations to survive these stochastic events depends on how individual animals respond to their altered environments, yet our understanding of the immediate and short-term behavioral responses of animals to acute disturbances remains poor. We focused on animal behavioral responses to the environmental disturbance created by megafire. Specifically, we explored the effects of the 2018 Mendocino Complex Fire in northern California, USA, on the behavior and body condition of black-tailed deer (Odocoileus hemionus columbianus). We predicted that deer would be displaced by the disturbance or experience high mortality post-fire if they stayed in the burn area. We used data from GPS collars on 18 individual deer to quantify patterns of home range use, movement, and habitat selection before and after the fire. We assessed changes in body condition using images from a camera trap grid. The fire burned through half of the study area, facilitating a comparison between deer in burned and unburned areas. Despite a dramatic reduction in vegetation in burned areas, deer showed high site fidelity to pre-fire home ranges, returning within hours of the fire. However, mean home range size doubled after the fire and corresponded to increased daily activity in a severely resource-depleted environment. Within their home ranges, deer also selected strongly for patches of surviving vegetation and woodland habitat, as these areas provided forage and cover in an otherwise desolate landscape. Deer body condition significantly decreased after the fire, likely as a result of a reduction in forage within their home ranges, but all collared deer survived for the duration of the study. Understanding the ways in which large mammals respond to disturbances such as wildfire is increasingly important as the extent and severity of such events increases across the world. While many animals are adapted to disturbance regimes, species that exhibit high site fidelity or otherwise fixed behavioral strategies may struggle to cope with increased climate instability and associated extreme disturbance events.

Cross-Context Responses to Novelty in Rural and Urban Small Mammals

The Anthropocene is the era of urbanization. The accelerating expansion of cities occurs at the expense of natural reservoirs of biodiversity and presents animals with challenges for which their evolutionary past might not have prepared them. Cognitive and behavioral adjustments to novelty could promote animals’ persistence under these altered conditions. We investigated the structure of, and covariance between, different aspects of responses to novelty in rural and urban small mammals of two non-commensal rodent species. We ran replicated experiments testing responses to three novelty types (object, food, or space) of 47 individual common voles (Microtus arvalis) and 41 individual striped field mice (Apodemus agrarius). We found partial support for the hypothesis that responses to novelty are structured, clustering (i) speed of responses, (ii) intensity of responses, and (iii) responses to food into separate dimensions. Rural and urban small mammals did not differ in most responses to novelty, suggesting that urban habitats do not reduce neophobia in these species. Further studies investigating whether comparable response patters are found throughout different stages of colonization, and along synurbanization processes of different duration, will help illuminate the dynamics of animals’ cognitive adjustments to urban life.

Innovative problem-solving in a threatened gull species, the Olrog's Gull (Larus atlanticus)

Innovation, a process that plays an important role in the ecology and evolution of species, is considered an expression of behavioral flexibility in animals. Here we analyzed innovative problem-solving ability and performance enhancement through learning in the Olrog's Gull (Larus atlanticus), under controlled processes and experimental conditions. Trials were undertaken with nine adult individuals captured at a highly urbanized coastal area of Argentina. Each individual was presented with a Plexiglas box that could be opened by pushing or pulling two lids, each lid leading to a separated food reward. We measured problem-solving ability through consumption latency and the number of solved lids. As explanatory variables, we measured contact rate, as a measure of persistence, and the number of effective contacts. The results showed that the contact rate and effective contacts did not affect variables related to problem-solving ability during the first confrontation of the individuals with the closed box. Consumption latency decreased significantly throughout the trials, and with increasing contact rate and effective contacts. The number of solved lids increased through the trials independently of the contact rate and the total effective contacts with the box. Although persistence did not influence individuals' performance during the problem-solving test; this variable affected individuals' ability to solve the task throughout trials. Learning was evidenced by the decrease in the resolution time across experiments, suggesting that successful individuals improved their performance probably through a trial-and-error process. Evaluation of behavioral responses of a threatened seabird to a novel problem-solving task adds knowledge to previous field studies and provides a better understanding of the ability of individuals to adjust their foraging behavior in highly urbanized areas used during the non-breeding season.

The duration of artificial light defines sexual signalling in the common glow-worm

Abstract

Artificial light at night is increasing globally, interfering with both sensory ecology and temporal rhythms of organisms, from zooplankton to mammals. This interference can change the behaviour of the affected organisms, and hence compromise the viability of their populations. Limiting the use of artificial light may mitigate these negative effects. Accordingly, we investigated whether the duration of artificial light affects sexual signalling in female glow-worms, Lampyris noctiluca, which are flightless and attract flying males to mate by emitting glow that is interfered by light pollution. The study included three treatments: no artificial light (control), 15 min of artificial light, and 45 min of artificial light. The results show that females were more likely to cease glowing when the exposure to light was longer. Furthermore, small females were more likely to cease their glow, and responded faster to the light, than larger females. These findings suggest that glow-worms can react rapidly to anthropogenic changes in nocturnal light levels, and that prolonged periods of artificial light trigger females to stop sexual signalling. Thus, limiting the duration of artificial light can mitigate the adverse effects of light pollution on sexual signalling, highlighting the importance of such mitigation measures.

Significance statement

Interest in the effects of artificial light at night on animal behaviour has increased in recent years. With evidence for its negative impact accumulating, potential remedies, such as limiting the duration of light exposure, have emerged. To date, however, knowledge on the effectiveness of these methods has remained very limited. We show that female European common glow-worms, which are wingless beetles that glow to attract flying males to mate, responded to prolonged artificial light exposure by discontinuing their glow. Such non-glowing females are not expected to find a mate, making it difficult for them to reproduce. Hence, our study indicates that the duration of artificial light should be limited to protect this night-active beetle and its opportunities for effective sexual signalling. Because many other nocturnal species also need darkness, this study provides valuable information for the development and use of less disruptive night-time lights.

Socioecology Explains Individual Variation in Urban Space Use in Response to Management in Cape Chacma Baboons (Papio ursinus)

The presence of wildlife adjacent to and within urban spaces is a growing phenomenon globally. When wildlife’s presence in urban spaces has negative impacts for people and wildlife, nonlethal and lethal interventions on animals invariably result. Recent evidence suggests that individuals in wild animal populations vary in both their propensity to use urban space and their response to nonlethal management methods. Understanding such interindividual differences and the drivers of urban space use could help inform management strategies. We use direct observation and high-resolution GPS (1 Hz) to track the space use of 13 adult individuals in a group of chacma baboons (Papio ursinus) living at the urban edge in Cape Town, South Africa. The group is managed by a dedicated team of field rangers, who use aversive conditioning to reduce the time spent by the group in urban spaces. Adult males are larger, more assertive, and more inclined to enter houses, and as such are disproportionately subject to “last resort” lethal management. Field rangers therefore focus efforts on curbing the movements of adult males, which, together with high-ranking females and their offspring, comprise the bulk of the group. However, our results reveal that this focus allows low-ranking, socially peripheral female baboons greater access to urban spaces. We suggest that movement of these females into urban spaces, alone or in small groups, is an adaptive response to management interventions, especially given that they have no natural predators. These results highlight the importance of conducting behavioral studies in conjunction with wildlife management, to ensure effective mitigation techniques.

Fine scale behaviour and time-budget in the cryptic ectotherm European pond turtle Emys orbicularis

For ectotherms, behaviour and associated energetic costs are directly related to thermal conditions. In the present context of global change, estimating time-budget for these species is relevant to assess and predict their capacity to adapt to near future. We tested the hypothesis that in ectotherms where reproduction is highly energy consuming, energy expenditure should vary throughout the breeding season with a maximum around nesting events. To test this hypothesis, we assessed the fine-scale behaviour, time-budget and estimated energetic costs in eight adult female European pond turtles Emys orbicularis equipped with data-loggers recording ambient temperature, pressure, light and the animals’ 3-axis acceleration. Deployments occurred over four months throughout the nesting season 2017 in semi-natural captive conditions in Alsace, France. All study turtles showed a clear daily pattern over the 24h cycle, with four distinct phases (referred to as Night, Morning, Midday and Evening), associated with different behaviours and activity levels. Before oviposition, turtles were mostly active during Morning, and activity was positively driven by ambient temperature. Activity levels doubled during the nesting period, mostly due to the increased activity in the Evening, when nesting events occurred. Throughout the active season, basking occurrence at Midday was related to air temperature but cloud coverage was an even more important factor. Our results are a first step in predicting the seasonal time and energy budgets of the European pond turtle, and demonstrate the usefulness of animal-borne accelerometers to study free living freshwater turtles over extended periods of time.

Variation in winter site fidelity within and among individuals influences movement behavior in a partially migratory ungulate

Many animals migrate to take advantage of temporal and spatial variability in resources. These benefits are offset with costs like increased energetic expenditure and travel through unfamiliar areas. Differences in the cost-benefit ratio for individuals may lead to partial migration with one portion of a population migrating while another does not. We investigated migration dynamics and winter site fidelity for a long-distance partial migrant, barren ground caribou (Rangifer tarandus granti) of the Teshekpuk Caribou Herd in northern Alaska. We used GPS telemetry for 76 female caribou over 164 annual movement trajectories to identify timing and location of migration and winter use, proportion of migrants, and fidelity to different herd wintering areas. We found within-individual variation in movement behavior and wintering area use by the Teshekpuk Caribou Herd, adding caribou to the growing list of ungulates that can exhibit migratory plasticity. Using a first passage time–net squared displacement approach, we classified 78.7% of annual movement paths as migration, 11.6% as residency, and 9.8% as another strategy. Timing and distance of migration varied by season and wintering area. Duration of migration was longer for fall migration than for spring, which may relate to the latter featuring more directed movement. Caribou utilized four wintering areas, with multiple areas used each year. This variation occurred not just among different individuals, but state sequence analyses indicated low fidelity of individuals to wintering areas among years. Variability in movement behavior can have fitness consequences. As caribou face the pressures of a rapidly warming Arctic and ongoing human development and activities, further research is needed to investigate what factors influence this diversity of behaviors in Alaska and across the circumpolar Arctic.

Seasonal changes in problem-solving in wild African striped mice

Innovative problem-solving ability is a predictor of whether animals can successfully cope with environmental changes. These environmental changes can test the limits of animals, for example when energy availability decreases seasonally and, hence, problem-solving performance decreases because less energy is available for cognitive processes. Here, we investigated: (1) how problem-solving performance changed between seasons that differed significantly in food availability; (2) whether these changes were related to environmentally induced physiological changes in blood glucose and ketone levels, indicators of energy availability; and (3) whether individual variation in problem-solving was related to sex differences. We studied 99 free-ranging African striped mice, Rhabdomys pumilio, in the Succulent Karoo, South Africa, 55 during the hot dry summer with low food availability and 44 during the cold wet winter with higher food availability. We measured their problem-solving abilities using a food extraction task and found no seasonal differences in problem-solving success. However, mice solved the problem faster in summer versus winter. In summer, food availability was reduced and blood ketones increased but there was no seasonal difference in blood glucose levels. There were no correlation between problem-solving performance and blood glucose or ketone levels. Overall, more males solved the task than females. It appears that in striped mice cognitive functions can be maintained under harsh environmental conditions.

Resource availability influences global social network properties in Gunnison’s prairie dogs (Cynomys gunnisoni)

Increasingly we are discovering that the interactions between individuals within social groups can be quite complex and flexible. Social network analysis offers a toolkit to describe and quantify social structure, the patterns we observe, and evaluate the social and environmental factors that shape group dynamics. Here, we used 14 Gunnison’s prairie dogs networks to evaluate how resource availability and network size influenced four global properties of the networks (centralization, clustering, average path length, small word index). Our results suggest a positive correlation between overall network cohesion and resource availability, such that networks became less centralized and cliquish as biomass/m2 availability decreased. We also discovered that network size modulates the link between social interactions and resource availability and is consistent with a more ‘decentralized’ group. This study highlights the importance of how individuals modify social cohesions and network connectedness as a way to reduce intragroup competition under different ecological conditions.

The role of individual behavioral traits on fishway passage attempt behavior

Variations in behavioral traits are widely recognized to drive animal behaviors exhibited within a population. However, information on how behavior traits influence behavior in anthropogenically modified habitats is lacking. Many habitats have become highly fragmented as a result of human processes. To mitigate this and improve habitat connectivity, wildlife passes are increasingly employed, with the aim of enabling animals to move freely between habitats. However, wildlife passes (e.g., fishways) are not always effective in achieving passage and it remains uncertain what factors play a role in an individual's likelihood of passing successfully. This study measured three behavioral traits (boldness, exploration, and activity) in juvenile brown trout (Salmo trutta; n = 78) under field conditions within a river and tested whether these behavior traits influenced both the passage success and the behaviors exhibited during upstream fishway passage attempts. Although behavioral traits were found and collapsed into two behavioral trait dimensions, behavioral traits had low repeatability and so did not contribute to a personality spectrum. Boldness was found to negatively influence the number of passage attempts carried out by an individual and to positively influence passage success, with bolder individuals carrying out fewer attempts and having an increased probability of passage success. No behavioral traits were found to be related to other passage metrics (passage success, Time until First Attempt, and Passage Duration) during the first passage. But all three behavioral traits were significantly negatively related to the changes in passage behaviors at consecutive, successful passage attempts, with bolder, more exploratory and more active individuals passing through a fishway quicker on the second passage than on the first. This study suggests that bolder and more active individuals may perform better during fishway passage attempts, particularly within rivers where multiple barriers to movement exist.

Complex life histories predispose aphids to recent abundance declines

Many animals change feeding habits as they progress through life stages, exploiting resources that vary in space and time. However, complex life histories may bring new risks if rapid environmental change disrupts the timing of these switches. Here, we use abundance times series for a diverse group of herbivorous insects, aphids, to search for trait and environmental characteristics associated with declines. Our meta dataset spanned three world regions and >300 aphid species, tracked at 75 individual sites for 10-50 years. Abundances were generally falling, with median changes of -8.3%, -5.6%, and -0.1% per year in the central USA, northwestern USA, and United Kingdom, respectively. Aphids that obligately alternated between host plants annually and those that were agricultural pests exhibited the steepest declines, relative to species able to persist on the same host plant year-round or those in natural areas. This suggests that host alternation might expose aphids to climate-induced phenology mismatches with one or more of their host plant species, with additional risks from exposure to insecticides and other management efforts. Warming temperatures through time were associated with milder aphid declines or even abundance increases, particularly at higher latitudes. Altogether, while a warming world appeared to benefit some aphid species in some places, most aphid species that had time-sensitive movements among multiple host plants seemed to face greater risk of decline. More generally, this suggests that recent human-induced rapid environmental change is rebalancing the risks and rewards associated with complex life histories.

Elevated temperature increases reproductive investment in less preferred mates in the invasive European corn borer moth

Rapidly changing environments may weaken sexual selection and lead to indiscriminate mating by interfering with the reception of mating signals or by increasing the costs associated with mate choice. If temperature alters sexual selection, it may impact population response and adaptation to climate change. Here, we examine how differences in temperature of the mating environment influence reproductive investment in the European corn borer moth (Ostrinia nubilalis). Mate preference in this species is known to be related to pheromone usage, with assortative mating occurring between genetically distinct E and Z strains that differ in the composition of female and male pheromones. We compared egg production within and between corn borer lines derived from four different populations that vary in pheromone composition and other traits. Pairs of adults were placed in a mating environment that matched the pupal environment (ambient temperature) or at elevated temperature (5°C above the pupal environment). At ambient temperature, we found that within-line pairs produced eggs sooner and produced more egg clusters than between-line pairs. However, at elevated temperature, between-line pairs produced the same number of egg clusters as within-line pairs. These results suggest that elevated temperature increased investment in matings with typically less preferred, between-line mates. This increased investment could result in changes in gene flow among corn borer populations in warming environments.

Sepal Identity of the Pappus and Floral Organ Development in the Common Dandelion (Taraxacum officinale; Asteraceae)

The dry one-seeded fruits (cypselae) of the Asteraceae are often crowned with a pappus, an appendage of hairs or scales that assists in dispersal. It is generally assumed, but little investigated, that the pappus represents the outer floral whorl where the sepals are usually located. We analysed pappus–sepal homology in dandelions using micromorphological and floral gene expression analyses. We show that the pappus initiates from a ring primordium at the base of the corolla, heterochronic to the petals. Pappus parts form from this ring, with those in the alternipetalaous position usually being ahead in growth, referring to sepal identity. Tof-APETALLA1 expression increased during floret development and was highest in mature pappus. Tof-PISTILLATA expression was high and confined to the floral tissues containing the petals and stamens, consistent with expectations for sepals. Apart from the pappus, the dispersal structure of dandelion consists of the upper part of the fruit, the beak, which originates from the inner floral whorl. Thus, our results support the homology of the pappus with the sepals, but show that it is highly derived. Together with our floral stage definitions and verified qPCR reference genes, they provide a basis for evolution and development studies in dandelions and possibly other Asteraceae.

Anthropogenic evolution in an insect wing polymorphism following widespread deforestation

Anthropogenic environmental change can underpin major shifts in natural selective regimes, and can thus alter the evolutionary trajectories of wild populations. However, little is known about the evolutionary impacts of deforestation-one of the most pervasive human-driven changes to terrestrial ecosystems globally. Absence of forest cover (i.e. exposure) has been suggested to play a role in selecting for insect flightlessness in montane ecosystems. Here, we capitalize on human-driven variation in alpine treeline elevation in New Zealand to test whether anthropogenic deforestation has caused shifts in the distributions of flight-capable and flightless phenotypes in a wing-polymorphic lineage of stoneflies from the Zelandoperla fenestrata species complex. Transect sampling revealed sharp transitions from flight-capable to flightless populations with increasing elevation. However, these phenotypic transitions were consistently delineated by the elevation of local treelines, rather than by absolute elevation, providing a novel example of human-driven evolution in response to recent deforestation. The inferred rapid shifts to flightlessness in newly deforested regions have implications for the evolution and conservation of invertebrate biodiversity.

Raised by aliens: constant exposure to an invasive predator triggers morphological but not behavioural plasticity in a threatened species tadpoles

During biotic invasions, native communities are abruptly exposed to novel and often severe selective pressures. The lack of common evolutionary history with invasive predators can hamper the expression of effective anti-predator responses in native prey, potentially accelerating population declines. Nonetheless, rapid adaptation and phenotypic plasticity may allow native species to cope with the new ecological pressures. We tested the hypothesis that phenotypic plasticity is fostered when facing invasive species and evaluated whether plasticity offers a pool of variability that might help the fixation of adaptive phenotypes. We assessed behavioural and morphological trait variation in tadpoles of the Italian agile frog (Rana latastei) in response to the invasive crayfish predator, Procambarus clarkii, by rearing tadpoles under different predation-risk regimes: non-lethal crayfish presence and crayfish absence. After two-month rearing, crayfish-exposed tadpoles showed a plastic shift in their body shape and increased tail muscle size, while behavioural tests showed no effect of crayfish exposure on tadpole behaviour. Furthermore, multivariate analyses revealed weak divergence in morphology between invaded and uninvaded populations, while plasticity levels were similar between invaded and uninvaded populations. Even if tadpoles displayed multiple plastic responses to the novel predator, none of these shifts underwent fixation after crayfish arrival (10–15 years). Overall, these findings highlight that native prey can finely tune their responses to invasive predators through plasticity, but the adaptive value of these responses in whitstanding the novel selective pressures, and the long-term consequences they can entail remain to be ascertained.

Divergence in heritable life history traits suggests potential for local adaptation and trade-offs associated with a coal ash disposal site

Globally, human activities have resulted in rapid environmental changes that present unique challenges for wildlife. However, investigations of local adaptation in response to simultaneous exposure to multiple anthropogenic selection pressures are rare and often generate conflicting results. We used an in situ reciprocal transplant design within a quantitative genetic framework to examine how adaptive evolution and phenotypic plasticity contribute to the persistence of an amphibian population inhabiting an environment characterized by high levels of multiple toxic trace elements. We found evidence of phenotypic divergence that is largely consistent with local adaptation to an environment contaminated with multiple chemical stressors, tied to potential trade-offs in the absence of contaminants. Specifically, the population derived from the contaminated environment had a reduced risk of mortality and greater larval growth and in the contaminated environment, relative to offspring from the naïve population. Further, while survival in the uncontaminated environment was not compromised in offspring from the contaminant-exposed population, they did show delayed development and reduced growth rates over larval development, relative to the naïve population. We found no evidence of reduced additive genetic variation in the contaminant-exposed population, suggesting long-term selection in a novel environment has not reduced the evolutionary potential of that population. We also saw little evidence that past selection in the ASH environment had reduced trait plasticity in the resident population. Maternal effects were prominent in early development, but we did not detect any trends suggesting these effects were associated with the maternal transfer of toxic trace elements. Our results demonstrate the potential for adaptation to multiple contaminants in a wild amphibian population, which may have facilitated long-term persistence in a heavily impacted environment.

What do we know (and need to know) about the role of urban habitats as ecological traps? Systematic review and meta-analysis

Urban areas represent a spectrum that goes from being safe habitats for biodiversity (i.e., habitats more or equally preferred, without costs to fitness) to being ecological traps (i.e., habitats more or equally preferred, but with costs to fitness). Given the imminent urban expansion, it is valuable to assess how biodiversity is responding to urbanization and thus generate timely conservation strategies. We systematically review the urban ecology literature to analyze how much do we know about the role of urban areas as ecological traps. Using a formal meta-analytical approach, we test whether urban areas are functioning as ecological traps or as safe habitats for different taxonomic groups. We generated a data set of 646 effect sizes of different measures of habitat preferences and fitness from 38 papers published between 1985 and 2020. The data set covered 15 countries and 47 urban areas from four continents, including 29 animal species. Studies from North America and Europe were best represented, and birds were the most studied taxa. Overall, the meta-analysis suggests that urbanized habitats are functioning more as safe sites than as ecological traps, mainly for certain species with characteristics that have allowed them to adapt well to urban areas. That is, many of the studied species prefer more urbanized habitats over other less urbanized sites, and their fitness is not modified, or it is even increased. However, there was high heterogeneity among studies. We also performed meta-regressions to identify variables accounting for this heterogeneity across studies and we demonstrate that outcomes may depend on methodological aspects of studies, such as study design or the approach used to measure habitat preference and fitness. More research is needed for poorly studied regions and on a wider range of species before generalizations can be made on the role of urban areas for biodiversity conservation.

Plastic adjustments of biparental care behavior across embryonic development under elevated temperature in a marine ectotherm

Phenotypic plasticity in parental care investment allows organisms to promptly respond to rapid environmental changes by potentially benefiting offspring survival and thus parental fitness. To date, a knowledge gap exists on whether plasticity in parental care behaviors can mediate responses to climate change in marine ectotherms. Here, we assessed the plasticity of parental care investment under elevated temperatures in a gonochoric marine annelid with biparental care, Ophryotrocha labronica, and investigated its role in maintaining the reproductive success of this species in a warming ocean. We measured the time individuals spent carrying out parental care activities across three phases of embryonic development, as well as the hatching success of the offspring as a proxy for reproductive success, at control (24℃) and elevated (27℃) temperature conditions. Under elevated temperature, we observed: (a) a significant decrease in total parental care activity, underpinned by a decreased in male and simultaneous parental care activity, in the late stage of embryonic development; and (b) a reduction in hatching success that was however not significantly related to changes in parental care activity levels. These findings, along with the observed unaltered somatic growth of parents and decreased brood size, suggest that potential cost-benefit trade-offs between offspring survival (i.e., immediate fitness) and parents' somatic condition (i.e., longer-term fitness potential) may occur under ongoing ocean warming. Finally, our results suggest that plasticity in parental care behavior is a mechanism able to partially mitigate the negative effects of temperature-dependent impacts.

Some Memories Never Fade: Inferring Multi-Scale Memory Effects on Habitat Selection of a Migratory Ungulate Using Step-Selection Functions

Understanding how animals use information about their environment to make movement decisions underpins our ability to explain drivers of and predict animal movement. Memory is the cognitive process that allows species to store information about experienced landscapes, however, remains an understudied topic in movement ecology. By studying how species select for familiar locations, visited recently and in the past, we can gain insight to how they store and use local information in multiple memory types. In this study, we analyzed the movements of a migratory mule deer (Odocoileus hemionus) population in the Piceance Basin of Colorado, United States to investigate the influence of spatial experience over different time scales on seasonal range habitat selection. We inferred the influence of short and long-term memory from the contribution to habitat selection of previous space use within the same season and during the prior year, respectively. We fit step-selection functions to GPS collar data from 32 female deer and tested the predictive ability of covariates representing current environmental conditions and both metrics of previous space use on habitat selection, inferring the latter as the influence of memory within and between seasons (summer vs. winter). Across individuals, models incorporating covariates representing both recent and past experience and environmental covariates performed best. In the top model, locations that had been previously visited within the same season and locations from previous seasons were more strongly selected relative to environmental covariates, which we interpret as evidence for the strong influence of both short- and long-term memory in driving seasonal range habitat selection. Further, the influence of previous space uses was stronger in the summer relative to winter, which is when deer in this population demonstrated strongest philopatry to their range. Our results suggest that mule deer update their seasonal range cognitive map in real time and retain long-term information about seasonal ranges, which supports the existing theory that memory is a mechanism leading to emergent space-use patterns such as site fidelity. Lastly, these findings provide novel insight into how species store and use information over different time scales.

Study on the impacts of LULC change on the wildlife habitat and the livelihood of people in and around Dampa Tiger Reserve, Mizoram, India

Anthropogenic activities are a matter of serious concern in the Indian Himalayan region due to adverse impacts on wildlife and habitats. This study examines resource use patterns by local people in relation to the habitat of Malayan Sun Bear in and around Dampa Tiger Reserve in Mizoram. Standard questionnaire surveys and vegetation sampling methods were used for data collection and analysis. It was found that 221.3 km2 (33.3%) of the forested areas have high human interference in the form of logging, indiscriminate tree falling and fuel wood collection, while 26% was moderately affected and 18% of the reserve had no impact. Among vegetation resources, fuel wood was used in the highest quantity (28%) followed by bamboo and edible plants (21%) and (11%), respectively. Ethno-zoological usage comprises of parts of animals like snake, bear, monitor lizard, and porcupine. Sun bears were considered pests that feed on maize, cucumber, sweet potato and pumpkins grown in ‘jhum’ crop fields. Anthropogenic pressures from farm-bush hunting, monoculture, and unplanned roads have contributed to severe biodiversity loss, and must be constrained for the conservation of sun bear and their habitat in the region.  The Land Use/ Land Cover on human built-up, jhum land (current and abandoned jhum/shifting cultivation), forests (dense and open), bamboo forest, plantation etc. were used to develop maps for each village. The land use pattern for the eight villages studied. Information obtained from MIRSAC and its mapping in Arcview shows that highest number of agricultural land was in villages of West Phaileng (319sq.ha) and Damparengpui (283.8sq.ha). Closed or dense forest was in highest proportion in Phuldungsei and least in Tuipuibari (120sq.ha). Grazing activities was relatively low or absent in most part of DTR. Abandoned jhum fields were in largest number in Damparengpui (939.60sq.ha) followed by Silsuri (881.17sq.ha) and Serhmun (880.99sq.ha).

Effects of oil palm and human presence on activity patterns of terrestrial mammals in the Colombian Llanos

The ability of animals to adjust their behaviour can influence how they respond to environmental changes and human presence. We quantified activity patterns of terrestrial mammals in oil palm plantations and native riparian forest in Colombia to determine if species exhibited behavioural changes depending on the type of habitat and the presence of humans. Despite the large sampling effort (12,403 camera-days), we were only able to examine the activity patterns of ten species in riparian forests and seven species in oil palm plantations, with four species (capybara, giant anteater, lesser anteater and common opossum) being represented by enough records (i.e. n > 20) in both oil palm and forest to allow robust comparisons. Only capybaras showed an apparent change in activity patterns between oil palm plantations and riparian forests, shifting from being crepuscular in forest to predominantly nocturnal inside oil palm plantations. Further, capybaras, giant anteaters and white-tailed deer appeared to modify their activities to avoid human presence inside oil palm plantations by increasing nocturnality (temporal overlap $$\widehat{\Delta }$$ Δ ^ ranged from 0.13 to 0.36), whereas jaguarundi had high overlap with human activities [$$\widehat{\Delta }$$ Δ ^ =0.85 (0.61–0.90)]. Species pair-wise analysis within oil palm revealed evidence for temporal segregation between species occupying the same trophic position (e.g. foxes and jaguarundi), whereas some predators and their prey (e.g. ocelots and armadillos) had high overlaps in temporal activity patterns as might be expected. Our findings shed light on the potential behavioural adaptation of mammals to anthropogenic landscapes, a feature not captured in traditional studies that focus on measures such as species richness or abundance.

Growth and reproduction by young urban and rural black bears

Human-dominated landscapes contain fragmented natural land cover interspersed throughout an urban matrix. Animals that occupy human-dominated landscapes often grow and reproduce differently than conspecifics. Female American black bears (Ursus americanus) produce litters for the first time usually at age 4 years; 2-year-olds rarely give birth. We visited winter bear dens and trapped bears in spring and summer to compare the reproductive output and weight of female black bears within the city limits of Asheville, North Carolina, and three forested rural sites in North Carolina and Virginia representative of the undeveloped habitat of Asheville. Urban yearling females weighed nearly double (45.0 kg ± 8.1 [± SD]; n = 36) that of yearling females from the three rural study sites (23.2 ± 8.5 [Pisgah], 23.6 ± 8.3 [Virginia SW], and 23.9 ± 9.7 [Virginia NW]; n = 95). Across all sites, hard mast production during the autumn, when females were cubs, did not affect their weights as yearlings. Seven of 12 (58%) 2-year-old urban bears produced 11 cubs (mean litter size = 1.6 ± 0.8), but no 2-year-old rural females produced cubs. Production of hard mast in the autumn, when females were yearlings, did not influence cub production by 2-year-old female bears at the urban site. We hypothesize that reproduction by 2-year-old bears is linked to the availability of anthropogenic food sources associated with urban environments. To inform population level management decisions, managers and researchers should quantify urban food sources and the effects on black bear life history. If high fecundity allows urban populations to sustain relatively high mortality rates, then urban bear populations may be source populations for surrounding, rural areas. Alternately, if reproduction in urban populations cannot match high time-specific or age-specific urban mortality rates, then urban populations may be sinks for the surrounding areas.

Response of Reeves's Pheasants Distribution to Human Infrastructure in the Dabie Mountains over the Last 20 Years

Simple Summary

Human infrastructure development drives habitat loss and fragmentation worldwide. In China, rapid infrastructure development impacts the habitats of endangered species. This study assessed how the distribution of Reeves’s pheasant, an endangered species of the International Union for Conservation of Nature (IUCN) and a nationally protected species of China, was potentially affected by human infrastructure development in the Dabie Mountains, the species’ main distribution range, over the past 20 years. We found that human infrastructure became more extensively distributed throughout the study area and closer to locations where Reeves’s pheasants were detected. Our results suggest that the increased density of buildings and roads in the Dabie Mountains may have caused a negative impact on Reeves’s pheasants.

Abstract

Human infrastructure development drives habitat loss and fragmentation worldwide. In China, over the last 20 years, rapid infrastructure development impacted the habitats of endangered species. To facilitate conservation efforts, studies of how human infrastructure affects the distribution of Reeves’s pheasant (Syrmaticus reevesii), an endangered species by the International Union for Conservation of Nature (IUCN) and a nationally protected species in China, are critically needed. We assessed how the distribution of Reeves’s pheasant was impacted by human infrastructure development over the past 20 years in the Dabie Mountains, the main distribution range of the species. We surveyed Reeves’s pheasants by direct sightings and indirect evidence through line transects which were randomly distributed in the Dabie Mountains from 2001 to 2002 and 2018 to 2019. We evaluated the variation of the roads and buildings in these areas in the last 20 years, and then modeled the relationship of the distribution of this pheasant with the road and building data from 2000 and 2017. Human infrastructure became more extensively distributed throughout the Dabie Mountains during the period, with all lands within 10 km of a road or a building. The distribution of Reeves’s pheasants became closer to the buildings and roads and there was a significantly positive relationship between the occurrence of Reeves’s pheasants and the distance to the nearest buildings and roads in 2018–2019. These results suggest that the increased density of buildings and roads in the Dabie Mountains may have caused negative effects on Reeves’s pheasants.

Neural and Molecular Mechanisms of Biological Embedding of Social Interactions

Animals operate in complex environments, and salient social information is encoded in the nervous system and then processed to initiate adaptive behavior. This encoding involves biological embedding, the process by which social experience affects the brain to influence future behavior. Biological embedding is an important conceptual framework for understanding social decision-making in the brain, as it encompasses multiple levels of organization that regulate how information is encoded and used to modify behavior. The framework we emphasize here is that social stimuli provoke short-term changes in neural activity that lead to changes in gene expression on longer timescales. This process, simplified-neurons are for today and genes are for tomorrow-enables the assessment of the valence of a social interaction, an appropriate and rapid response, and subsequent modification of neural circuitry to change future behavioral inclinations in anticipation of environmental changes. We review recent research on the neural and molecular basis of biological embedding in the context of social interactions, with a special focus on the honeybee.

Anticipated effects of abiotic environmental change on intraspecific social interactions

Social interactions are ubiquitous across the animal kingdom. A variety of ecological and evolutionary processes are dependent on social interactions, such as movement, disease spread, information transmission, and density-dependent reproduction and survival. Social interactions, like any behaviour, are context dependent, varying with environmental conditions. Currently, environments are changing rapidly across multiple dimensions, becoming warmer and more variable, while habitats are increasingly fragmented and contaminated with pollutants. Social interactions are expected to change in response to these stressors and to continue to change into the future. However, a comprehensive understanding of the form and magnitude of the effects of these environmental changes on social interactions is currently lacking. Focusing on four major forms of rapid environmental change currently occurring, we review how these changing environmental gradients are expected to have immediate effects on social interactions such as communication, agonistic behaviours, and group formation, which will thereby induce changes in social organisation including mating systems, dominance hierarchies, and collective behaviour. Our review covers intraspecific variation in social interactions across environments, including studies in both the wild and in laboratory settings, and across a range of taxa. The expected responses of social behaviour to environmental change are diverse, but we identify several general themes. First, very dry, variable, fragmented, or polluted environments are likely to destabilise existing social systems. This occurs as these conditions limit the energy available for complex social interactions and affect dissimilar phenotypes differently. Second, a given environmental change can lead to opposite responses in social behaviour, and the direction of the response often hinges on the natural history of the organism in question. Third, our review highlights the fact that changes in environmental factors are not occurring in isolation: multiple factors are changing simultaneously, which may have antagonistic or synergistic effects, and more work should be done to understand these combined effects. We close by identifying methodological and analytical techniques that might help to study the response of social interactions to changing environments, highlight consistent patterns among taxa, and predict subsequent evolutionary change. We expect that the changes in social interactions that we document here will have consequences for individuals, groups, and for the ecology and evolution of populations, and therefore warrant a central place in the study of animal populations, particularly in an era of rapid environmental change.

Species' traits drive amphibian tolerance to anthropogenic habitat modification

Anthropogenic habitat modification is accelerating, threatening the world's biodiversity. Understanding species' responses to anthropogenic modification is vital for halting species' declines. However, this information is lacking for globally threatened amphibians, informed primarily by small community-level studies. We integrated >126,000 verified citizen science observations of frogs, with a global continuous measure of anthropogenic habitat modification for a continental scale analysis of the effects of habitat modification on frogs. We derived a modification tolerance index-accounting for anthropogenic stressors such as human habitation, agriculture, transport and energy production-for 87 species (36% of all Australian frog species). We used this index to quantify and rank each species' tolerance of anthropogenic habitat modification, then compiled traits of all the frog species and assessed how well these equipped species to tolerate modified habitats. Most of Australia's frog species examined were adversely affected by habitat modification. Habitat specialists and species with large geographic range sizes were the least tolerant of habitat modification. Call dominant frequency, body size, clutch type and calling position (i.e. from vegetation) were also related to tolerance of habitat modification. There is an urgent need for improved consideration of anthropogenic impacts and improved conservation measures to ensure the long-term persistence of frog populations, particularly focused on specialists and species identified as intolerant of modified habitats.

Wild geladas (Theropithecus gelada) in crops-more than in pasture areas-reduce aggression and affiliation

Human-primate interfaces are expanding and, despite recent studies on primates from peri-urban environments, little research exists on the impact of agriculture and/or pasture areas on primate social behavior and health. We assessed how crop/pasture areas potentially alter social behavior and health of wild geladas (Theropithecus gelada) frequenting the unprotected area of Kundi (Ethiopia). We predicted that compared to pasture areas, crop areas (i) would be more challenging for geladas (prediction 1) and (ii) would have a greater impact on both aggressive and affiliative behavior, by reducing grooming time and enhancing competition (prediction 2). During January-May 2019 and December 2019-February 2020, we collected data (via scan, focal animal sampling, and video analyses) on direct human disturbance, external signs of pathologies and social behavior of 140 individuals from 14 one-male units and two all-male units. Animals experienced the highest level of human disturbance in crop areas (in line with prediction 1). Individuals from the groups preferentially frequenting crop areas showed the highest prevalence of external signs of pathologies consistent with chemical and biological contamination (alopecia/abnormally swollen parts). We collected 48 fecal samples. Samples from frequent crop users contained the highest rates of parasitic elements/gram (egg/larva/oocyst/cyst) from Entamoeba histolytica/dispar, a parasite common in human settlements of the Amhara region. In crop areas, subjects spent less time grooming but engaged in lower rates of intense aggression (in partial agreement with prediction 2). We speculate that the reduction in social behavior may be a tactic adopted by geladas to minimize the likelihood of detection and maximize food intake while foraging in crops.