An experimental test of changed personality in butterflies from anthropogenic landscapes

Animal personality in multiple stressor environments: the evolutionary ecology of among-individual differences in responses to stressor suites

Animal personality differences may have evolved as alternative strategies for negotiating multiple stressor landscapes. Indeed, ecologists are increasingly recognizing that interactions among multiple stressors can transform selective landscapes and behavioural and physiological responses to stress regimes. Yet, evaluating this hypothesis poses challenges, as most studies involving relationships between personality variation and the environment consider single stressors. Here, we review the literature to explore the theory and evidence that multiple stressor environments may mediate personality variation. We consider effects on evolution of personality variation, as influenced by life-history, energetic and behavioural trade-offs, and effects on phenotypic expression of personality traits. We then explore how personality variation may modulate behavioural and physiological responses to multiple stressors, and how differential responses may be affected by personality-dependent movement ecology and cognitive strategies. Among-individual differences in responses to multiple stressors are critical to elucidate, as multi-stress interactions may transform animal behavioural and physiological responses relative to those predicted under single stressor scenarios, and because among-individual variation comprises the basis for evolutionary shifts in stress responsiveness and population resiliency to global environmental change.

The country toad and the city toad: comparing morphology of invasive cane toads (Rhinella marina) from rural and urban environments

Urbanization is a principal driver of global biodiversity loss. Although many studies have examined the impacts of urbanization on biodiversity, we are only beginning to study urbanization as an evolutionary force. Urban environments are hotspots for invasive species, but most previous studies have focused on phenotypic changes in native species responding to urbanization. Quantifying the phenotypic responses of invasive species to urbanization may help reveal mechanisms promoting invasion. There are, however, few studies investigating the phenotypic response of invasive species to urbanization. We compared morphological traits of invasive cane toads (Rhinella marina) between urban and rural areas in three cities in north-eastern Australia using generalized linear mixed models. We found that the parotoid glands, which are the major anti-predator defence of toads were smaller in urban than in rural populations. The tibiofibula length of males in urban populations was longer than those in rural populations, but females showed opposite trends, suggesting potential effects of urbanization on sexual dimorphism. These results demonstrate that urbanization drives morphological changes in invasive toads, suggesting they may adapt to urban environments rapidly.

Urban Individuals of Three Rove Beetle Species Are Not More Exploratory or Risk-Taking Than Rural Conspecifics

Urbanization is creating changes in environmental and habitat conditions, as well as creating disturbance and threats to urban-associated species. Some traits, such as high exploratory and risk-taking behavior, are beneficial to allow colonization of urban habitats and coping with urbanization-derived pressures. In this study the exploratory and risk-taking behavior of rural and urban individuals of three forest-associated rove beetle species were tested during their main reproductive period by five frequently used behavioral measures. Individuals of all studied species were similarly ranked by all behavioral measures, indicating that the studied rove beetles responded consistently in the different contexts. However, the behavior of beetles was consistent over time for all/most studied species only by using two measures of exploratory behavior. These provide evidence for the existence of the exploratory dimension of personality in rove beetles. We found a higher exploratory behavior in males than females in Ocypus nitens which can be explained by the active searching of males for mating partners. There were no urbanization-related differences in the exploratory behavior of individuals, suggesting that behavioral changes (being more exploratory) may not yield additional fitness benefits in these rove beetle species with good dispersal capacity.

Are There Personality Differences between Rural vs. Urban-Living Individuals of a Specialist Ground Beetle, Carabus convexus?

Simple Summary

Urbanization causes substantial changes in environmental and habitat conditions. These, as well as more frequent disturbance events accompanying urbanization constitute selective forces acting on various reactions of urban-associated species, including behavior. In this study, rural and urban individuals of a forest specialist ground beetle, Carabus convexus were tested for their exploratory and risk-taking behavior. Beetles responded consistently in the different contexts, and also over time, demonstrating that they had personalities. Carabus convexus is the second ground beetle species in which the existence of personality was demonstrated. By agglomerative cluster analysis, we identified two groups of behavioral traits: the exploratory and the risk-taking dimensions of personality. Urban females were significantly more exploratory than urban males which can be an adaptation to find high quality food needed to mature eggs, as well as to find favorable microsites for oviposition. Moreover, urban females and males showed higher level of risk-taking behavior than rural females. Urban beetles with higher risk-taking behavior may be better able to cope with new conditions created by frequent urbanization-driven disturbance events.

Abstract

The world-wide, rapid urbanization is leading to substantial changes in environmental and habitat conditions. These changes, as well as disturbances accompanying urbanization have considerable effects at various levels of the biological organization on wildlife. Understanding behavioral responses to such changes is essential for identifying which organisms may successfully adapt to the altered conditions. In this study, individuals of a forest specialist ground beetle, Carabus convexus, from rural and urban forest patches were tested for their exploratory and risk-taking behavior. Beetles responded consistently in the different contexts; furthermore, by behaving consistently over time, demonstrated that they had personalities. Agglomerative cluster analysis identified two groups of behavioral traits: the exploratory and the risk-taking dimension of personality. Urban females were significantly more exploratory than urban males which can be an adaptation to find high quality food needed to mature eggs in urban habitats, as well as to select favorable microsites for oviposition. Moreover, urban females and males showed more risk-taking behavior than rural females. Urban beetles with more risk-taking behavior may be better able to cope with frequent urbanization-driven disturbance events.

Urbanization as a disrupter and facilitator of insect herbivore behaviors and life cycles

Insect herbivores require a variety of habitats across their life cycle, with behavior often mediating transitions between life stages or habitats. Human management strongly alters urban habitats, yet herbivore behavior is rarely examined in cities. We review the existing literature on several key behaviors: host finding, feeding, egg placement and pupation location, and antipredator defense. We emphasize that unapparent portions of the life cycle, such as the habitat of the overwintering stage, may influence if urbanized areas act as population sources or sinks. Here, management of the soil surface and aboveground biomass are two areas with especially pressing research gaps. Lastly, high variability in urban environments may select for more plastic behaviors or greater generalism. We encourage future research that assesses both behavior and less apparent portions of insect life cycles to determine best practices for conservation and management.

The expanding role of movement behavior in insect conservation ecology

Insect conservation will rely on incorporating behavior into management. Dispersal behavior is one such vital behavior for conservation, but it is generally poorly understood at the species level. We reviewed recent literature to identify intricacies that complicate including dispersal behavior in conservation management. Many previous theories used to predict the need to disperse do not explicitly address successful dispersal. Additionally, we found identifying barriers to dispersal as a possible way to improve conservation management, but it is necessary to consider multiple parts of dispersal (emigration, matrix navigation, immigration). Species' dispersal is context-specific. Therefore, to effectively incorporate dispersal behavior into conservation, more research is necessary on individual species' responses to their environment, how they navigate to optimal sites, and their fitness after dispersal events.

Adaptive Evolution in Cities: Progress and Misconceptions

Current narratives suggest that urban adaptation - the adaptive evolution of organisms to cities - is pervasive across taxa and cities. However, in reviewing hundreds of studies, we find only six comprehensive examples of species adaptively evolving to urbanization. We discuss the utility and shortcomings of methods for studying urban adaptation. We then review diverse systems offering preliminary evidence for urban adaptation and outline a research program for advancing its study. Urban environments constitute diverse, interacting selective agents that test the limits of adaptation. Understanding urban adaptation therefore offers unique opportunities for addressing fundamental questions in evolutionary biology and for better conserving biodiversity in cities. However, capitalizing on these opportunities requires appropriate research methods and dissemination of accurate narratives.