Urbanization and biological invasion shape animal personalities

The relationship between unpredictability in childhood and depression among college students: the mediating roles of coping style and resilience

BACKGROUND

According to previous studies, unpredictability in childhood could significantly increase the risk of depression in adulthood. Only a few studies have explored the relationship between these two variables in China. This paper aims to explore the relationship between unpredictability in childhood and depression and examine the mediating roles of coping styles and resilience.

METHODS

We investigated 601 college students, who had an average age of 19.09 (SD = 2.78) years. Participants completed questionnaires regarding unpredictability in childhood, coping style, resilience, and depression. We analyzed survey data using the bias-corrected bootstrap method.

RESULTS

The findings revealed a significant positive association between unpredictability in childhood and depression among college students. Mature coping style, immature coping style, and resilience were found to mediate this relationship independently. Furthermore, the study unveiled a serial mediation process, wherein both mature and immature coping styles, followed by resilience, sequentially mediate the relationship between unpredictability in childhood and depression, underscoring the complex interplay between these variables.

CONCLUSIONS

The results indicated that the risk of depression among college students who have experienced unpredictable childhood should be valued. Attention to coping styles and resilience should be paid to decrease depression among college students who have experienced unpredictable childhood.

Predator-driven behavioural shifts in a common lizard shape resource-flow from marine to terrestrial ecosystems

Foraging decisions shape the structure of food webs. Therefore, a behavioural shift in a single species can potentially modify resource-flow dynamics of entire ecosystems. To examine this, we conducted a field experiment to assess foraging niche dynamics of semi-arboreal brown anole lizards in the presence/absence of predatory ground-dwelling curly-tailed lizards in a replicated set of island ecosystems. One year after experimental translocation, brown anoles exposed to these predators had drastically increased perch height and reduced consumption of marine-derived food resources. This foraging niche shift altered marine-to-terrestrial resource-flow dynamics and persisted in the diets of the first-generation offspring. Furthermore, female lizards that displayed more risk-taking behaviours consumed more marine prey on islands with predators present. Our results show how predator-driven rapid behavioural shifts can alter food-web connectivity between oceanic and terrestrial ecosystems and underscore the importance of studying behaviour-mediated niche shifts to understand ecosystem functioning in rapidly changing environments.

Urban and rural male song sparrows (Melospiza melodia) differ in territorial aggression and activation of vasotocin neurons in response to song challenge

When living in urban habitats, 'urban adapter' species often show greater aggression toward conspecifics, yet we do not understand the mechanisms underlying this behavioral shift. The neuroendocrine system regulates socio-sexual behaviors including aggression and thus could mediate behavioral responses to urbanization. Indeed, urban male song sparrows (Melospiza melodia), which are more territorially aggressive, also have greater abundance of the neuropeptide arginine vasotocin (AVT) in nodes of the brain social behavior network. Higher abundance of AVT could reflect long-term synthesis that underlies baseline territoriality or short-term changes that regulate aggression in response to social challenge. To begin to resolve the timeframe over which the AVT system contributes to habitat differences in aggression we used immediate early gene co-expression as a measure of the activation of AVT neurons. We compared Fos induction in AVT-immunoreactive neurons of the bed nucleus of the stria terminalis (BSTm) and paraventricular nucleus of the hypothalamus (PVN) between urban and rural male song sparrows in response to a short (< 5 min.) or long (> 30 min.) song playback to simulate territorial intrusion by another male. We found that urban males had a higher proportion of Fos-positive AVT neurons in both brain regions compared to rural males, regardless of the duration of song playback. Our results suggest that AVT neurons remain activated in urban males, independently of the duration of social challenge. These findings that Fos induction in AVT neurons differs between rural and urban male song sparrows further implicate this system in regulating behavioral responses to urbanization.

Bibliometric investigation of the integration of animal personality in conservation contexts

Consistent individual differences in behavior, commonly termed animal personality, are a widespread phenomenon across taxa that have important consequences for fitness, natural selection, and trophic interactions. Animal personality research may prove useful in several conservation contexts, but which contexts remains to be determined. We conducted a structured literature review of 654 studies identified by combining search terms for animal personality and various conservation subfields. We scored the relevance of personality and conservation issues for each study to identify which studies meaningfully integrated the 2 fields as opposed to surface-level connections or vague allusions. We found a taxonomic bias toward mammals (29% of all studies). Very few amphibian or reptile studies applied personality research to conservation issues (6% each). Climate change (21%), invasive species (15%), and captive breeding and reintroduction (13%) were the most abundant conservation subfields that occurred in our search, though a substantial proportion of these papers weakly integrated conservation and animal personality (climate change 54%, invasive species 51%, captive breeding and reintroduction 40%). Based on our results, we recommend that researchers strive for consistent and broadly applicable terminology when describing consistent behavioral differences to minimize confusion and improve the searchability of research. We identify several gaps in the literature that appear to be promising and fruitful avenues for future research, such as disease transmission as a function of sociability or exploration as a driver of space use in protected areas. Practitioners can begin informing future conservation efforts with knowledge gained from animal personality research.

Going, Going, Gone The Diminishing Capacity of Museum Specimen Collections to Address Global Change Research: A Case Study on Urban Reptiles

It has been increasingly popular to use natural history specimens to examine environmental changes. As the current functionality of museum specimens has extended beyond their traditional taxonomic role, there has been a renewed focus on the completeness of biological collections to provide data for current and future research. We used the collections of the Western Australian Museum to answer questions about the change in occurrence of five common reptile species due to the rapid urbanization of Perth. We recorded a significant decline in collection effort from the year 2000 onwards (F = 7.65, p < 0.01) compared to the period 1990–1999. Spatial analysis revealed that only 0.5% of our study region was well sampled, 8.5% were moderately sampled and the majority of the regions (91%) were poorly sampled. By analysing the trend of specimen acquisition from 1950 to 2010, we discovered a significant inconsistency in specimen sampling effort for 13 common reptile species across time and space. A large proportion of past specimens lacked information including the place and time of collection. An increase in investment to museums and an increase in geographically and temporally systematic collecting is advocated to ensure that collections can answer questions about environmental change.

Do Suburban Populations of Lizards Behave Differently from Forest Ones? An Analysis of Perch Height, Time Budget, and Display Rate in the Cuban Endemic Anolis homolechis

Urbanization transforms natural ecosystems into novel habitats, which can result in negative consequences for biodiversity. Therefore, it is important to understand the mechanisms of maintenance of native species in urbanized environments, including behavior—which can act as a fast response to rapid environmental changes. We compared some behavioral traits between two suburban and two forest populations of Anolis homolechis. Direct observations of 779 individuals revealed that perch height was positively influenced by body size, but not by sex. Suburban individuals perched higher than forest ones, and even more so in the afternoon compared to the morning; a behavior that was not observed in forests populations. These differences might be due to a change from foraging activities in the morning to vigilance, display, and/or thermoregulation in the afternoon, promoted by suburban habitat conditions (e.g., higher predator abundance, open habitat structure, and urban heat). Video recordings of 81 focal individuals showed that males were more active than females (i.e., spending less time in stationary behavior and having a higher display rate), with no significant effect of habitat type. As some of our results diverge from previous studies on invasive anoles, we recommend extending comparative studies of urban and non-urban populations to other native Anolis.

Urbanization increases fluctuating asymmetry and affects behavioral traits of a common grasshopper

Urbanization has a major impact on biodiversity. For many organisms, the urbanization process means environmental stress caused by fragmentation and increased temperatures in cities and atmospheric, soil, light, and noise pollution. Such environmental stress can influence both the morphology and behavior of animals. Hence, individuals might be selected for survival-facilitating traits under high pressures in urban areas. The specific impact of urbanization on insect behavior is still largely unexplored. We studied the impact of urbanization on one of the most common grasshopper species in Germany, Chorthippus biguttulus, by comparing morphological and behavioral traits of individuals sampled from grasslands with low, medium, and high urbanization levels. We first investigated whether urbanization as a stressor affected body size and fluctuating asymmetry in the locomotor organs. Next, we examined whether urbanization induced changes in the individuals' boldness and activity. Our results showed that fluctuating asymmetry of grasshoppers' locomotory organs increased more than twofold with urbanization level. Further, individuals' boldness and walking activity increased from areas with low to high urbanization levels. Our results indicate strong responses of grasshoppers in terms of morphology and behavior to the urban environment. To compensate for urbanization effects on arthropod populations, management strategies need to be developed that maintain ecological processes and reduce environmental stress in urban areas.

Chromosome-scale genome assembly of the brown anole (Anolis sagrei), an emerging model species

Rapid technological improvements are democratizing access to high quality, chromosome-scale genome assemblies. No longer the domain of only the most highly studied model organisms, now non-traditional and emerging model species can be genome-enabled using a combination of sequencing technologies and assembly software. Consequently, old ideas built on sparse sampling across the tree of life have recently been amended in the face of genomic data drawn from a growing number of high-quality reference genomes. Arguably the most valuable are those long-studied species for which much is already known about their biology; what many term emerging model species. Here, we report a highly complete chromosome-scale genome assembly for the brown anole, Anolis sagrei – a lizard species widely studied across a variety of disciplines and for which a high-quality reference genome was long overdue. This assembly exceeds the vast majority of existing reptile and snake genomes in contiguity (N50 = 253.6 Mb) and annotation completeness. Through the analysis of this genome and population resequence data, we examine the history of repetitive element accumulation, identify the X chromosome, and propose a hypothesis for the evolutionary history of fusions between autosomes and the X that led to the sex chromosomes of A. sagrei.

A highly-complete chromosome-scale genome assembly of the brown anole, Anolis sagrei, provides insight into the evolution of sex chromosomes and is a crucial resource for this model lizard species.

Eating More and Fighting Less: Social Foraging Is a Potential Advantage for Successful Expansion of Bird Source Populations

Animals can expand distributions in response to climatic and environmental changes, but the potential expansive ability of a source population is rarely evaluated using designed experiments. Group foraging can increase survival in new environments, but it also increases intraspecific competition. The trade-off between benefit and conflict needs to be determined. The expanding Light-vented Bulbul Pycnonotus sinensis was used as a model to test mechanisms promoting successful expansion. Social foraging and its advantages were evaluated using lab-designed feeding trials. Consuming novel foods was compared between bulbuls and a sympatric, nonexpansive relative species, the finchbill Spizixos semitorques, from native areas at both solitary and social levels. Bulbuls increased their eating times when transferred from solitary to group, whereas social context did not affect finchbills. Bulbuls were significantly more likely to eat with their companions than finchbills when in a group. Thus, exploring food resources in a bulbul source population was facilitated by social context, indicating that social foraging is an important means by which birds successfully expand and respond to environmental changes. This research increases understanding of successful expansion mechanisms and will consequently help predict invasive potentials of alien species.

Individual variation, personality, and the ability of animals to cope with climate change

The Sixth Assessment of the Intergovernmental Panel on Climate Change describes negative effects of climate change on animals occurring on a larger scale than previously appreciated. Animal species are increasingly experiencing more frequent and extreme weather in comparison with conditions in which the species evolved. Individual variation in behavioural and physiological responses of animals to stimuli from the environment is ubiquitous across all species. Populations with relatively high levels of individual variation are more likely to be able to survive in a range of environmental conditions and cope with climate change than populations with low levels of variation. Behavioural and physiological responses are linked in animals, and personality can be defined as consistent individual behavioural and physiological responses of animals to changes in their immediate environment. Glucocorticoids (cortisol and corticosterone) are hormones that, in addition to metabolic roles, are released when the neuroendocrine stress system is activated in response to stimuli from the environment perceived to be threatening. The size of a glucocorticoid response of an animal is an indication of the animal’s personality. Animals with reactive personalities have relatively high glucocorticoid responses, are relatively slow and thorough to explore new situations, and are more flexible and able to cope with changing or unpredictable conditions than animals with proactive personalities. Animals with reactive personalities are likely to be better able to cope with environmental changes due to climate change than animals with proactive personalities. A reaction norm shows the relationship between phenotype and environmental conditions, with the slope of a reaction norm for an individual animal a measure of phenotypic plasticity. If reaction norm slopes are not parallel, there is individual variation in plasticity. Populations with relatively high individual variation in plasticity of reaction norms will have more animals that can adjust to a new situation than populations with little variation in plasticity, so are more likely to persist as environments change due to climate change. Future studies of individual variation in plasticity of responses to changing environments will help understanding of how populations of animals may be able to cope with climate change.

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.

Native Lizards Living in Brazilian Cities: Effects of Developmental Environments on Thermal Sensitivity and Morpho-Functional Associations of Locomotion

Environmental conditions often affect developmental processes and consequently influence the range of phenotypic variation expressed at population level. Expansion of urban sites poses new challenges for native species, as urbanization usually affects the intensity of solar exposure and shade availability, determining the thermal regimes organisms are exposed to. In this study, we evaluate the effects of different developmental conditions in a Tropidurus lizard commonly found in Brazilian urban sites. After incubating embryos of Tropidurus catalanensis in two different thermal regimes (Developmental Environments [DE]: cold 24°C and warm 30°C), we measured morphological traits in the neonates and quantified locomotor performance in horizontal and vertical surfaces at three temperatures [Test Temperatures (TT) = 24°C, 30°C and 36°C]. Results indicate effects of developmental temperatures on morphological features, expressing functional implications that might be decisive for the viability of T. catalanensis in urbanized areas. Lizards ran similarly on horizontal and vertical surfaces, and isolated analyses did not identify significant effects of DE or TT on the sprint speeds measured. Absolute Vmax (i.e., the maximum sprint speed reached among all TTs) positively correlated with body size (SVL), and neonates from the warm DE (30°C) were larger than those from the cold DE (24°C). Morpho-functional associations of absolute Vmax also involved pelvic girdle width and forelimb, hindlimb, trunk, and tail lengths. Emerging discussions aim to understand how animals cope with abrupt environmental shifts, a likely common challenge in urbanized sites. Our findings add a new dimension to the topic, providing evidence that temperature, an environmental parameter often affected by urbanization, influences the thermal sensitivity of locomotion and the morphological profile of T. catalanensis neonates. Thermal sensitivity of specific developmental processes may influence the ability of these lizards to remain in habitats that change fast, as those suffering rapid urbanization due to city growth.

The natural history of model organisms: the rhesus macaque as a success story of the Anthropocene

Of all the non-human primate species studied by researchers, the rhesus macaque (Macaca mulatta) is likely the most widely used across biological disciplines. Rhesus macaques have thrived during the Anthropocene and now have the largest natural range of any non-human primate. They are highly social, exhibit marked genetic diversity, and display remarkable niche flexibility (which allows them to live in a range of habitats and survive on a variety of diets). These characteristics mean that rhesus macaques are well-suited for understanding the links between sociality, health and fitness, and also for investigating intra-specific variation, adaptation and other topics in evolutionary ecology.

Nesting in Anolis Lizards: An Understudied Topic in a Well-Studied Clade

Maternal nesting behavior in oviparous species strongly influences the environmental conditions their embryos experience during development. In turn, these early-life conditions have consequences for offspring phenotypes and many fitness components across an individual’s lifespan. Thus, identifying the evolutionary and ecological causes and effects of nesting behavior is a key goal of behavioral ecology. Studies of reptiles have contributed greatly to our understanding of how nesting behavior shapes offspring phenotypes. While some taxonomic groups have been used extensively to provide insights into this important area of biology, many groups remain poorly studied. For example, the squamate genus Anolis has served as a model to study behavior, ecology, and evolution, but research focused on Anolis nesting behavior and developmental plasticity is comparatively scarce. This dearth of empirical research may be attributed to logistical challenges (e.g., difficulty locating nests), biological factors (e.g., their single-egg clutches may hinder some experimental designs), and a historical focus on males in Anolis research. Although there is a gap in the literature concerning Anolis nesting behavior, interest in nesting ecology and developmental plasticity in this group has grown in recent years. In this paper, we (1) review existing studies of anole nesting ecology and developmental plasticity; (2) highlight areas of anole nesting ecology that are currently understudied and discuss how research in these areas can contribute to broader topics (e.g., maternal effects and global change biology); and (3) provide guidelines for studying anole nesting in the field. Overall, this review provides a foundation for establishing anoles as models to study nesting ecology and developmental plasticity.

Small mammal personalities generate context dependence in the seed dispersal mutualism

Mutualisms are foundational components of ecosystems with the capacity to generate biodiversity through adaptation and coevolution and give rise to essential services such as pollination and seed dispersal. To understand how mutualistic interactions shape communities and ecosystems, we must identify the mechanisms that underlie their functioning. One mechanism that may drive mutualisms to vary in space and time is the unique behavioral types, or personalities, of the individuals involved. Here, our goal was to examine interindividual variation in the seed dispersal mutualism and identify the role that different personalities play. In a field experiment, we observed individual deer mice (Peromyscus maniculatus) with known personality traits predating and dispersing seeds in a natural environment and classified all observed interactions made by individuals as either positive or negative. We then scored mice on a continuum from antagonistic to mutualistic and found that within a population of scatter hoarders, some individuals are more mutualistic than others and that one factor driving this distinction is animal personality. Through this empirical work, we provide a conceptual advancement to the study of mutualism by integrating it with the study of intraspecific behavioral variation. These findings indicate that animal personality is a previously overlooked mechanism generating context dependence in plant–animal interactions and suggest that behavioral diversity may have important consequences for the functioning of mutualisms.

Invasive alien species as an environmental stressor and its effects on coping style in a native competitor, the Eurasian red squirrel

Free-living animals cope with environmental stressors through physiological and behavioural responses. According to the unidimensional model, these responses are integrated within a coping style: proactive individuals (bold, active-explorative and social) have a lower hypothalamic-pituitary-adrenal (HPA) axis reactivity than reactive ones (shy, less active-explorative, less social). These associations may change when individuals are exposed to human-induced rapid environmental change (HIREC), such as the introduction of invasive alien species (IAS). Here, we studied Eurasian red squirrels to investigate the relationship between personality traits and one integrated measure of HPA axis activity, both in areas uncolonized (natural populations) and colonized by an IAS, the Eastern grey squirrel (invaded populations). We expected an association between physiological and behavioural responses, and that activity, exploration and social tendency would covary, forming a behavioural syndrome in natural populations, while competition with the IAS was predicted to disrupt these associations. We used faecal glucocorticoid metabolites (FGMs) as an integrated measure of adrenocortical activity, and measured the levels of four personality traits (exploration, activity, activity-exploration and social tendency) with an open field test and a mirror image stimulation test. We found no correlation between FGMs and personality traits, neither in natural nor invaded populations. However, we found correlations among personality traits in areas without interspecific competition, indicating a behavioural syndrome, which was disrupted in invaded populations. This is one of the few studies showing that an IAS, acting as an environmental stressor, alters a native species' behavioural syndrome, but does not influence its coping style.

Bold or shy? Examining the risk–taking behavior and neophobia of invasive and non–invasive house sparrows

Behavior provides a useful framework for understanding specialization, with animal personality aiding our understanding of the invasiveness of birds. Invasions imply dispersion into unknown areas and could require changes in behavior or spatial clustering based on personality. Reduced neophobia and increased exploring behavior could allow individuals to colonize new areas as they test and use non–familiar resources. Here, we hypothesized that house sparrow (Passer domesticus) individuals from invasive populations would exhibit bolder behavior than in non–invasive populations. We assessed risk taking and neophobia in male house sparrows in Barcelona (where it is considered native) and in Mexico City (where it has become widely invasive), captured in two different habitats, urban and non–urban. We assessed latency to enter an experimental cage and to explore it, and latency to feed and feeding time in the presence of a novel object. We found that sparrows from Mexico City, both from urban and non–urban areas, were quicker to enter the experimental cage than the sparrows from Barcelona. The time it took the birds to start exploring the cage gave a similar result. We found no differences between cities or habitats in the latency to feed and feeding time while exposed to a novel object. Our results partially support the view that the invader populations from Mexico City are bolder than those from Barcelona. Behavior is an important component of plasticity and its variability may have an important effect on adaptation to local situations. Future studies should disentangle the underlying mechanisms that explain the different personalities found in populations of different regions, contrasting populations of different densities, and taking different food availability scenarios into account.

Do I stay or do I go? Shifts in perch use by lizards during morning twilight suggest anticipatory behaviour

Anticipatory behaviour is the expectation of a near-future event based on information processed in the past and influences an animal's tactical decisions, particularly when there are significant fitness consequences. The grass lizard (Takydromus viridipunctatus) perches on blades of grass at night which likely reduces the probability of predation by terrestrial predators such as snakes, rodents and shrews. During twilight (starting 30 min before sunrise), they move from above the grass to within grass clumps and this is thought to afford the lizard protection while reducing detection by avian predators. Here, we examined how lizards shift their behaviour as a function of visual detectability to their primary predator, the cattle egret (Bubulcus ibis). We show that the lizards shift from their perch site during twilight at the earliest time at which egrets depart communal roosts. At the same time, visual modelling shows a dramatic increase in the detectability of the lizards to the visual system of egrets. Therefore, anticipatory behaviour in response to environmental cues acts to reduce predation risk as lizards become more conspicuous and predators become more active. Grass lizard anticipatory behaviour appears to be finely tuned by natural selection to adjust to temporal changes in predation risk.

Urban bat pups take after their mothers and are bolder and faster learners than rural pups

BACKGROUND

Urbanization is rapidly changing our planet and animals that live in urban environments must quickly adjust their behavior. One of the most prevalent behavioral characteristics of urban dwelling animals is an increased level of risk-taking. Here, we aimed to reveal how urban fruitbats become risk-takers, and how they differ behaviorally from rural bats, studying both genetic and non-genetic factors that might play a role in the process. We assessed the personality of newborn pups from both rural and urban colonies before they acquired experience outdoors, examining risk-taking, exploration, and learning rates.

RESULTS

Urban pups exhibited significantly higher risk-taking levels, they were faster learners, but less exploratory than their rural counterparts. A cross-fostering experiment revealed that pups were more similar to their adoptive mothers, thus suggesting a non-genetic mechanism and pointing towards a maternal effect. We moreover found that lactating urban mothers have higher cortisol levels in their milk, which could potentially explain the transmission of some personality traits from mother to pup.

CONCLUSIONS

Young bats seem to acquire environment suitable traits via post-birth non-genetic maternal effects. We offer a potential mechanism for how urban pups can acquire urban-suitable behavioral traits through hormonal transfer from their mothers.

Wild boar in the city: Phenotypic responses to urbanisation

Urbanisation is a global human-induced environmental change and one of the most important threats to biodiversity. To survive in human-modified environments, wildlife must adjust to the challenging selection pressures of urban areas through behaviour, morphology, physiology and/or genetic changes. Here we explore the effect of urbanisation in a large, highly adaptable and generalist urban adapter species, the wild boar (Sus scrofa, Linnaeus 1758). From 2005 to 2018, we gathered wild boar data and samples from three areas in NE Spain: one urban (Barcelona municipality, n = 445), and two non-urban (Serra de Collserola Natural Park, n = 183, and Sant Llorenç del Munt i Serra de l'Obac Natural Park, n = 54). We investigated whether urbanisation influenced wild boar body size, body mass, body condition, and the concentration of serum metabolites, considering also the effect of age, sex and use of anthropogenic food resources. Wild boars from the urban area had larger body size, higher body mass, better body condition, and a higher triglyceride and lower creatinine serum concentrations than non-urban wild boars. In addition, urban wild boars consumed food from anthropogenic origin more frequently, which suggests that differences in their diet probably induced the biometric and the metabolic changes observed. These responses are probably adaptive and suggest that wild boars are thriving in the urban environment. Our results show that urbanisation can change the morphological and physiological traits of a large mammal urban adapter, which may have consequences in the ecology and response to urban selection pressures by the species. The phenotypic plasticity shown by wild boars provides both further and new evidence on the mechanisms that allow urban adapter species of greater size to respond to urbanisation, which is expected to continue growing globally over the coming decades.

Urban invaders are not bold risk-takers: a study of 3 invasive lizards in Southern California

Biological invasions threaten biodiversity worldwide, and therefore, understanding the traits of successful invaders could mitigate their spread. Many commonly invasive species do well in disturbed habitats, such as urban environments, and their abilities to effectively respond to disturbances could contribute to their invasiveness. Yet, there are noninvasive species that also do well in disturbed habitats. The question remains whether urban invaders behave differently in urban environments than noninvaders, which could suggest an "urban-exploiting" phenotype. In Southern California, the co-occurrence of invasive Italian wall lizards Podarcis siculus, brown anoles Anolis sagrei, and green anoles A. carolinensis, and native western fence lizards Sceloporus occidentalis offers an opportunity to test whether invasives exhibit consistent differences in risk-taking within human-altered habitats compared with a native species. We predicted that invasive lizards would exhibit more bold behavior by having shorter flight-initiation distances (FIDs) and by being found farther from a refuge (behaviors that would presumably maximize foraging in low-risk environments). Invasive populations had similar or longer FIDs, but were consistently found at distances closer to a refuge. Collectively, invasive lizards in urban habitats were not bolder than a native species. Reliance on nearby refuges might help species successfully invade urban habitats, and if a general pattern, may pose an added challenge in detecting or eliminating them.

Big City Living: A Global Meta-Analysis Reveals Positive Impact of Urbanization on Body Size in Lizards

Urban environments pose different selective pressures than natural ones, leading to changes in animal behavior, physiology, and morphology. Understanding how animals respond to urbanization could inform the management of urban habitats. Non-avian reptiles have important roles in ecosystems worldwide, yet their responses to urbanization have not been as comprehensively studied as those of mammals and birds. However, unlike mammals and birds, most reptiles cannot easily move away from disturbances, making the selective pressure to adapt to urban environments especially strong. In recent years, there has been a surge in research on the responses of lizards to urbanization, yet no formal synthesis has determined what makes an urban lizard, in other words, which phenotypic traits are most likely to change with urbanization and in which direction? Here, we present a qualitative synthesis of the literature and a quantitative phylogenetic meta-analysis comparing phenotypic traits between urban and non-urban lizard populations. The most robust finding from our analysis is that urban lizards are larger than their non-urban counterparts. This result remained consistent between sexes and taxonomic groups. Hence, lizards that pass through the urban filter have access to better resources, more time for foraging, and/or there is selection on attaining a larger body size. Other results included an increase in the diameters of perches used and longer limb and digit lengths, although this may be a result of increased body size. Urban lizards were not bolder, more active or exploratory, and did not differ in immune responses than non-urban populations. Overall, studies are biased to a few geographic regions and taxa. More than 70% of all data came from three species of anoles in the family Dactyloidae, making it difficult to generalize patterns to other clades. Thus, more studies are needed across multiple taxa and habitats to produce meaningful predictions that could help inform conservation and management of urban ecological communities.

The Role of Animal Cognition in Human-Wildlife Interactions

Humans have a profound effect on the planet's ecosystems, and unprecedented rates of human population growth and urbanization have brought wild animals into increasing contact with people. For many species, appropriate responses toward humans are likely to be critical to survival and reproductive success. Although numerous studies have investigated the impacts of human activity on biodiversity and species distributions, relatively few have examined the effects of humans on the behavioral responses of animals during human-wildlife encounters, and the cognitive processes underpinning those responses. Furthermore, while humans often present a significant threat to animals, the presence or behavior of people may be also associated with benefits, such as food rewards. In scenarios where humans vary in their behavior, wild animals would be expected to benefit from the ability to discriminate between dangerous, neutral and rewarding people. Additionally, individual differences in cognitive and behavioral phenotypes and past experiences with humans may affect animals' ability to exploit human-dominated environments and respond appropriately to human cues. In this review, we examine the cues that wild animals use to modulate their behavioral responses toward humans, such as human facial features and gaze direction. We discuss when wild animals are expected to attend to certain cues, how information is used, and the cognitive mechanisms involved. We consider how the cognitive abilities of wild animals are likely to be under selection by humans and therefore influence population and community composition. We conclude by highlighting the need for long-term studies on free-living, wild animals to fully understand the causes and ecological consequences of variation in responses to human cues. The effects of humans on wildlife behavior are likely to be substantial, and a detailed understanding of these effects is key to implementing effective conservation strategies and managing human-wildlife conflict.

Small mammals in the big city: Behavioural adjustments of non-commensal rodents to urban environments

A fundamental focus of current ecological and evolutionary research is to illuminate the drivers of animals' success in coping with human-induced rapid environmental change (HIREC). Behavioural adaptations are likely to play a major role in coping with HIREC because behaviour largely determines how individuals interact with their surroundings. A substantial body of research reports behavioural modifications in urban dwellers compared to rural conspecifics. However, it is often unknown whether the observed phenotypic divergence is due to phenotypic plasticity or the product of genetic adaptations. Here, we aimed at investigating (a) whether behavioural differences arise also between rural and urban populations of non-commensal rodents; and (b) whether these differences result from behavioural flexibility or from intrinsic behavioural characteristics, such as genetic or maternal effects. We captured and kept under common environment conditions 42 rural and 52 urban adult common voles (Microtus arvalis) from seven subpopulations along a rural-urban gradient. We investigated individual variation in behavioural responses associated with risk-taking and exploration, in situ at the time of capture in the field and ex situ after 3 months in captivity. Urban dwellers were bolder and more explorative than rural conspecifics at the time of capture in their respective sites (in situ). However, when tested under common environmental conditions ex situ, rural individuals showed little change in their behavioural responses whereas urban individuals altered their behaviour considerably and were consistently shyer and less explorative than when tested in situ. The combination of elevated risk-taking and exploration with high behavioural flexibility might allow urban populations to successfully cope with the challenges of HIREC. Investigating whether the observed differences in behavioural flexibility are adaptive and how they are shaped by additive and interactive effects of genetic make-up and past environmental conditions will help illuminate eco-evolutionary dynamics under HIREC and predict persistence of populations under urban conditions.

Metabolic and behavioral adaptations of greater white-toothed shrews to urban conditions

The global trend of urbanization is creating novel challenges for many animal species. Studies investigating behavioral differences between rural and urban populations often report a general increase in risk-taking behaviors in urban populations. According to the most common energy management model (the performance model), behaviors that increase access to resources, such as aggression and boldness, and behaviors that consume net energy, like locomotion and stress responses, are both positively correlated to resting metabolic rate (RMR). Thus, we expect urban populations to not only exhibit a higher level of risk-taking behavior but also a higher RMR. However, these interactions remain poorly investigated. Our main goal was to analyze the relationship between RMR and risk-taking behaviors in the greater white-toothed shrew (Crocidura russula) in rural versus urban populations. Trapped shrews were brought to captivity where we measured RMR, boldness, and exploration rate three times in each individual. Our findings revealed that urban shrews were indeed bolder and more exploratory, but contrary to our expectations, their RMR was lower than that of rural shrews. This is likely explained by differences in the environmental conditions of these two habitats, such as higher ambient temperatures and/or lower prey availability in cities. When looking at each population separately, this relationship remained similar: urban shrews with a higher RMR were less bold, and rural shrews with a higher RMR showed a lower exploration rate. We conclude that the energetic strategy of C. russula is dependent on the environmental and observational context and cannot be explained by the performance model.

Habitat urbanization and stress response are primary predictors of personality variation in northern cardinals (Cardinalis cardinalis)

Behavioral traits that vary consistently among individuals across different contexts are often termed as ‘personality traits,’ while the correlated suite formed by those traits is called a ‘behavioral syndrome’. Both personality trait and behavioral syndrome are potentially responsive to animal ‘states’, defined as strategically relevant individual features affecting the cost-and-benefit trade-offs of behavioral actions. Both extrinsic ‘states’ (e.g. urban versus rural habitats), and intrinsic ‘states’ (e.g. sex), may shape among-individual variation in personality traits, as well as behavioral syndromes. Here, we used northern cardinals sampled from four locations to examine the effect of habitat type (urban versus rural, an extrinsic state), stress hormone corticosterone (CORT) parameters, body weight and sex (intrinsic states) on personality traits and behavioral syndrome variation. We used behavioral trials to measure five personality traits. Using principal component analysis to quantify personality traits first, followed by general linear mixed models, we found that habitat type, CORT at capture and 2-day CORT response affected some personality traits, while body weight and sex did not. Cardinals inhabiting more urbanized areas had lower CORT metabolite levels at capture and were more neophilic, less neophobic and also less aggressive than their rural conspecifics. Using structural equation modeling to construct behavioral syndromes formed by our selected personality traits, we found that urban and rural cardinals varied in the models representing syndrome structure. When utilizing the shared syndrome structural model to examine the effects of states, habitat type and 2-day CORT response appear to affect syndrome variation in a coordinated, not hierarchical, manner.

Of city and village mice: behavioural adjustments of striped field mice to urban environments

A fundamental question of current ecological research concerns the drives and limits of species responses to human-induced rapid environmental change (HIREC). Behavioural responses to HIREC are a key component because behaviour links individual responses to population and community changes. Ongoing fast urbanization provides an ideal setting to test the functional role of behaviour for responses to HIREC. Consistent behavioural differences between conspecifics (animal personality) may be important determinants or constraints of animals’ adaptation to urban habitats. We tested whether urban and rural populations of small mammals differ in mean trait expression, flexibility and repeatability of behaviours associated to risk-taking and exploratory tendencies. Using a standardized behavioural test in the field, we quantified spatial exploration and boldness of striped field mice (Apodemus agrarius, n = 96) from nine sub-populations, presenting different levels of urbanisation and anthropogenic disturbance. The level of urbanisation positively correlated with boldness, spatial exploration and behavioural flexibility, with urban dwellers being bolder, more explorative and more flexible in some traits than rural conspecifics. Thus, individuals seem to distribute in a non-random way in response to human disturbance based on their behavioural characteristics. Animal personality might therefore play a key role in successful coping with the challenges of HIREC.

Adaptations of the red fox (Vulpes vulpes) to urban environments in Sydney, Australia

With urban encroachment on wild landscapes accelerating globally, there is an urgent need to understand how wildlife is adapting to anthropogenic change. We compared the behaviour of the invasive red fox (Vulpes vulpes) at eight urban and eight peri-urban areas of Sydney, Australia. We observed fox behaviour around a lure and compared fox activity patterns to those of potential prey and to two domestic predators (dogs—Canis lupus familiaris and cats—Felis catus). We assessed the influence of site type, vegetation cover, and distance from habitation on fox behaviour, and compared the temporal activity patterns of urban and peri-urban red foxes. Urban red foxes were marginally more nocturnal than those in peri-urban areas (88% activity overlap). There was greater overlap of red fox activity patterns with introduced mammalian prey in urban areas compared with peri-urban areas (90% urban vs 84% peri-urban). Red fox temporal activity overlapped 78% with cats, but only 20% with dogs, across both site types. The high degree of overlap with cats and introduced mammalian prey is most likely explained by the nocturnal behaviour of these species, while pet dogs are generally kept in yards or indoors at night. The behavioural differences we documented by urban red foxes suggest they may adapt to human modifications and presence, by being more nocturnal and/or more confident in urban areas.

Recent biological invasion shapes species recognition and aggressive behaviour in a native species: A behavioural experiment using robots in the field

Invasive species are a world-wide threat to biodiversity. Yet, our understanding of biological invasions remains incomplete, partly due to the difficulty of tracking and studying behavioural interactions in recently created species interactions. We tested whether the interactions between the recently introduced invasive lizard Anolis cristatellus and the native Anolis oculatus in Dominica have led to changes in species recognition and aggressive behaviour of the native species. The use of realistic robots allowed us to test the behavioural response of 131 A. oculatus males towards relevant and controlled conspecific versus heterospecific stimuli, directly in the field and in two contexts (allopatry vs. sympatry). Our results show that species recognition evolved prior to sympatry in A. oculatus. Moreover, interspecific competition resulted in an increase in the time spent displaying and a divergence in the aggressive behaviour of the native species towards conspecifics versus heterospecifics. Inherent species recognition and higher aggressive behaviour may limit species coexistence as they are expected to favour A. oculatus during territorial interactions with A. cristatellus. While more studies are needed to understand the causes of these behavioural shifts and their consequences on long-term species coexistence, the present study highlights the role of behaviour as a first response to interspecific interactions.

Phylogenetic signal and evolutionary correlates of urban tolerance in a widespread neotropical lizard clade

Urbanization is intensifying worldwide, and while some species tolerate and even exploit urban environments, many others are excluded entirely from this new habitat. Understanding the factors that underlie tolerance of urbanization is thus of rapidly growing importance. Here, we examine urban tolerance across a diverse group of lizards: Caribbean members of the neotropical genus Anolis. Our analyses reveal that urban tolerance has strong phylogenetic signal, suggesting that closely related species tend to respond similarly to urban environments. We propose that this characteristic of urban tolerance in anoles may be used to forecast the possible responses of species to increasing urbanization. In addition, we identified several key ecological and morphological traits that tend to be associated with tolerance in Anolis. Specifically, species experiencing hot and dry conditions in their natural environment and those that maintain higher body temperatures tend to have greater tolerance of urban habitats. We also found that tolerance of urbanization is positively associated with toepad lamella number and negatively associated with ventral scale density and relative hindlimb length. The identification of factors that predispose a species to be more or less urban tolerant can provide a starting point for conservation and sustainable development in our increasingly urbanized world.

Nestled in the city heat: urban nesting behavior enhances embryo development of an invasive lizard

Urbanization transforms many aspects of natural landscapes and poses many new challenges for individual survival and population persistence. Thus, urbanization provides an opportunity to examine how organisms deal with novel environmental change. Many studies provide evidence of phenotypic adaptation to urban environments, but few focus on responses during early life stages. Filling this information gap is important, because early life stages are particularly sensitive to abiotic factors, and no population is sustainable without successful embryo development. We tested the hypotheses that (i) embryos tolerate warmer temperature conditions of urbanized areas and (ii) maternal nesting behavior protects embryos from potentially lethal thermal conditions in urbanized habitats. We studied introduced populations of a subtropical lizard, Anolis cristatellus, in suburban and forested areas in Miami, Florida. In each habitat, we measured microenvironment variables for locations that females used for nesting vs. locations they did not use. We then incubated eggs from both populations under thermal conditions that mimicked used and unused sites. Nests in the suburban site were warmer than in the forest; however, in the suburban site, locations that females used were relatively cool compared with locations that were not used. We found no evidence that embryos are adapted to their respective suburban or forested thermal environments, but rather maternal nest-site choice enhanced embryo development in the suburban habitat. Maternal nesting behavior is likely an important factor for population persistence under major environmental changes, and a key contributor to the establishment and spread of invasive organisms across urbanized landscapes.

Effects of trap confinement on personality measurements in two terrestrial rodents

In recent years, consistent individual differences in behavior, or personalities, have been a topic of increasing interest as researchers strive to understand and predict the responses of individuals and populations to anthropogenic changes. Behavioral studies in wild populations often require that animals are live trapped before behavioral observation can occur, and this is especially true in studies investigating animal personalities. However, it is unknown whether the amount of time confined to a live trap may regulate the behavior of trapped individuals. Specifically, if the duration of trap confinement directly influences behavior, then by obtaining wild animals through live trapping we may be confounding the very measurements of greatest interest. To investigate whether the duration of trap confinement influences the behavior of trapped individuals, we performed a study on two small mammal species, focusing specifically on personality traits. We positioned high-definition trail cameras facing Longworth small mammal traps in the field to observe capture events and record the time of capture. We then measured personality in captured deer mice (Peromyscus maniculatus) and southern red-backed voles (Myodes gapperi) using three standardized tests, and through linear and generalized linear models we found that the time an animal had spent confined to a trap before testing did not affect 86% of behaviors exhibited. Our results showed two weak behavioral effects of confinement duration on boldness and docility resulting from an interaction between the duration of confinement and whether or not an individual was naïve to trapping. Our results suggest that behavioral measurements of wild, trapped small mammals are not determined by the time spent confined to a trap. However, researchers should use caution and consider whether an animal is naïve to trapping during analysis since habituation to the live trap may play a role in the effects of confinement duration on behavior.

Artificial light at night increases growth and reproductive output in Anolis lizards

Since the invention of electric lighting, artificial light at night (ALAN) has become a defining, and evolutionary novel, feature of human-altered environments especially in cities. ALAN imposes negative impacts on many organisms, including disrupting endocrine function, metabolism, and reproduction. However, we do not know how generalized these impacts are across taxa that exploit urban environments. We exposed brown anole lizards, an abundant and invasive urban exploiter, to relevant levels of ALAN in the laboratory and assessed effects on growth and reproduction at the start of the breeding season. Male and female anoles exposed to ALAN increased growth and did not suffer increased levels of corticosterone. ALAN exposure induced earlier egg-laying, likely by mimicking a longer photoperiod, and increased reproductive output without reducing offspring quality. These increases in growth and reproduction should increase fitness. Anoles, and potentially other taxa, may be resistant to some negative effects of ALAN and able to take advantage of the novel niche space ALAN creates. ALAN and both its negative and positive impacts may play a crucial role in determining which species invade and exploit urban environments.

Lymnaea stagnalis as model for translational neuroscience research: From pond to bench

The purpose of this review is to illustrate how a reductionistic, but sophisticated, approach based on the use of a simple model system such as the pond snail Lymnaea stagnalis (L. stagnalis), might be useful to address fundamental questions in learning and memory. L. stagnalis, as a model, provides an interesting platform to investigate the dialog between the synapse and the nucleus and vice versa during memory and learning. More importantly, the "molecular actors" of the memory dialogue are well-conserved both across phylogenetic groups and learning paradigms, involving single- or multi-trials, aversion or reward, operant or classical conditioning. At the same time, this model could help to study how, where and when the memory dialog is impaired in stressful conditions and during aging and neurodegeneration in humans and thus offers new insights and targets in order to develop innovative therapies and technology for the treatment of a range of neurological and neurodegenerative disorders.

Space use by animals on the urban fringe: interactive effects of sex and personality

Personality traits shape individual perceptions of risks and rewards, and so, should affect how animals value and use their environment. Evidence is emerging that personality affects foraging, space use, and exploitation of novel environments such as urban habitat. But the influence of personality is also hypothesized to be sex-dependent when primary motivation for space use differs between sexes, as often occurs in polygynous species. We tested the influence of personality traits, interacting with sex, on space use by the polygynous common brushtail possum, Trichosurus vulpecula, in an urban-woodland boundary in Sydney, Australia. We quantified personality traits, including exploration, using behavioral assays in an artificial arena. We also GPS-tracked free-ranging individuals, and measured range size, core area: home range, and proportional urban range. We found that personality traits affected space use either as a main effect or, as predicted, an interaction with sex. More exploratory animals, regardless of sex, had higher core area: home range ratios and proportionally larger ranges within urban habitat. However, less exploratory females yet more exploratory males had larger ranges. Our findings provide new insight into movement ecology by demonstrating, for the first time, the sex-dependent influence of personality. The demonstrated influence of personality on urban use by possums also suggests a personality filter for wildlife, as populations transition into urban areas. Finally, as individuals at the interface between urban and natural habitat are also a conduit between the two, a corollary of our findings is that there may be personality-mediated spread of disease across this boundary.