Animal Personality Research Articles

RESPONSES OF JUVENILE AMERICAN ALLIGATORS (ALLIGATOR MISSISSIPPIENSIS) TO CONTACT CALLS

Abstract Crocodylians are known for their ability to vocalize throughout their lives in a variety of social and ecological contexts, particularly during their vulnerable juvenile life stage. However, few studies have analyzed juvenile calls in laboratory settings, fewer still have analyzed them across large sample sizes or with respect to sex and body size, and no studies to date have analyzed crocodylian vocalizations with respect to human conditioning in captivity or animal personality profiles. This study tests juvenile American alligators' (Alligator mississippiensis) ability to respond via movement and callback vocalizations to pre-recorded conspecific contact calls across a large sample size (n=36), and tests for relationships between response rates and juvenile body size and sex. Seventeen and sixteen individuals out of a total of thirty-six responded via movement toward the source of pre-recorded vocalizations across the first and second experimental trials, respectively, whereas none responded through movement toward control sounds; 75% of juveniles who vocalized did so only in response to contact calls rather than controls (though the latter difference was not significant given that only four vocalized in Trial 1, and only a single animal vocalized in Trial 2); there was also no significant difference in movement toward recorded vocalizations across size or sex. However, one particularly vocal individual whose upbringing in captivity was known was identified as a possible unique personality profile given its propensity for callback vocalizations in comparison to its fellow study subjects.

The covariance between metabolic rate and behaviour varies across behaviours and thermal types: meta-analytic insights.

Energy metabolism has received much attention as a potential driver of repeatable among-individual differences in behaviour (animal personality). Several factors have been hypothesized to mediate this relationship. We performed a systematic review with a meta-analysis of >70 studies comprised of >8000 individuals reporting relationships between measures of maintenance metabolic rates (i.e. basal metabolic rate, resting metabolic rate, and standard metabolic rate) and behaviour. We evaluated support for three hypothesized mediators: (i) type of behaviour, (ii) opportunities for energy re-allocation, and (iii) magnitude of energetic constraints. Relationships between measures of maintenance metabolic rate (MR) and behaviour are predicted to be strongest for behaviours with strong consequences for energy turnover (acquisition or expenditure). Consistent with this, we found that behaviours with known consequences for energy gain (e.g. foraging, dominance, boldness) or expenditure (e.g. maximum sprint speed, sustained running speed, maximum distance travelled, etc.) had strong positive correlations with MR, while behaviours with putatively weak and/or inconsistent associations with net energy gain or loss (e.g. exploration, activity, sociability) were not correlated with MR. Greater opportunities for energy reallocation are predicted to weaken relationships between MR and behaviour by creating alternative pathways to balance energy budgets. We tested this by contrasting relationships between MR and behaviour in ectotherms versus endotherms, as thermoregulation in endotherms creates additional opportunities for energy reallocation compared with ectotherms. As predicted, the relationship between behaviour and MR was stronger in ectotherms compared with endotherms. However, statistical analyses of heterogeneity among effect sizes from different species did not support energy re-allocation as the main driver of these differences. Finally, we tested whether conditions where animals face greater constraints in meeting their energy budgets (e.g. field versus laboratory, breeding versus non-breeding) increased the strength of the relationship between MR and behaviour. We found that the relationship between MR and behaviour was unaffected by either of these modifiers. This meta-analysis provides two key insights. First, we observed positive relationships of similar magnitude between MR and behaviours that bring in net energy, and behaviours that cost net energy. This result is only consistent with a performance energy-management model. Given that the studies included in our meta-analysis represent a wide range of taxa, this suggests that the performance model may be the most common model in general. Second, we found that behaviours with putatively weak or inconsistent consequences for net energy gain or expenditure (exploration, activity, sociability) show no relationship with MR. The lack of relationship between MR and behavioural traits with weak and/or inconsistent consequences for energy turnover provides the first systematic demonstration of the central importance of the ecological function of traits in mediating relationships between MR and behaviour.

Brain size predicts behavioural plasticity in guppies (Poecilia reticulata): An experiment.

Understanding how animal personality (consistent between-individual behavioural differences) arises has become a central topic in behavioural sciences. This endeavour is complicated by the fact that not only the mean behaviour of individuals (behavioural type) but also the strength of their reaction to environmental change (behavioural plasticity) varies consistently. Personality and cognitive abilities are linked, and we suggest that behavioural plasticity could also be explained by differences in brain size (a proxy for cognitive abilities), since accurate decisions are likely essential to make behavioural plasticity beneficial. We test this idea in guppies (Poecilia reticulata), artificially selected for large and small brain size, which show clear cognitive differences between selection lines. To test whether those lines differed in behavioural plasticity, we reared them in groups in structurally enriched environments and then placed adults individually into empty tanks, where we presented them daily with visual predator cues and monitored their behaviour for 20days with video-aided motion tracking. We found that individuals differed consistently in activity and risk-taking, as well as in behavioural plasticity. In activity, only the large-brained lines demonstrated habituation (increased activity) to the new environment, whereas in risk-taking, we found sensitization (decreased risk-taking) in both brain size lines. We conclude that brain size, potentially via increasing cognitive abilities, may increase behavioural plasticity, which in turn can improve habituation to novel environments. However, the effects seem to be behaviour-specific. Our results suggest that brain size likely explains some of the variation in behavioural plasticity found at the intraspecific level.

Behavioral syndromes vary among geographically distinct populations in a reptile

A key goal in the study of animal personalities is to determine their adaptive potential and importance for behavioral evolution. Behavioral syndromes are evolutionarily intriguing because they suggest that an adaptive change in one behavior requires a concomitant shift in another. Within species, behavioral syndromes might be evolutionarily constrained by intrinsic mechanisms that restrict behaviors from evolving independently. Alternatively, behavioral correlations might easily be decoupled over short evolutionary time scales due to variation in selective pressures between environments. In this regard, comparative studies that explore differences in diverse aspects of personality between geographically distinct populations can provide valuable insights into the evolutionary processes acting on different behavioral tendencies. Accordingly, we investigated how behavioral types and behavioral syndromes differed across four geographically distinct populations of the delicate skink, Lampropholis delicata. We found strong evidence of mean trait-level variation in activity, exploration, and boldness across populations, suggesting adaptation to local environmental conditions. Similarly, we found that within-population correlations involving boldness varied substantially between populations. However, we did find a consistent within- and among-population correlation between activity and exploration, suggesting that this behavioral syndrome is relatively stable and could explain behavioral divergence in activity and exploration between populations. We suggest that there may be thermal physiological mechanisms that could be limiting the adaptive potential of an activity-exploration correlation in the delicate skink. Broadly, we argue that some behavioral correlations may be more adaptive than others, and that this should be more regularly considered within the animal personality framework. Animals have personalities which have important consequences for individual survival and population dynamics. We compared personality traits between 4 populations of a lizard to understand how different personalities might evolve. Populations expressed markedly diverse personalities, but we did find in all populations that lizards which were most active were also the most explorative. Our results suggest that some personalities are mostly shaped by environmental factors, whereas others are mediated by internal constraints like physiology.

Physiological differences between winter phenotypes of Siberian hamsters do not correlate with their behaviour

Living in a seasonally changing environment requires periodic, reversible changes in animals' phenotypes to match variations in their abiotic and biotic environments. These changes may relate to temperature regulation, torpor use, basal metabolic rate, body mass or behaviour, all acting in concert to ensure the best adjustment to the environmental challenges. As winter approaches, many small mammals develop a winter phenotype that is qualitatively and quantitatively different from a summer one. However, there is a significant within-population polymorphism in winter phenotype. We hypothesized that winter phenotype is correlated with consistent between-individual differences in animal behaviour, i.e. animal personality, and energy metabolism. We measured basal metabolic rate (BMR) and behavioural traits in three winter phenotypes of Siberian hamsters, Phodopus sungorus, which were acclimated to summer-like and then to winter-like conditions: fully responding, nonresponding and partially responding to a short photoperiod. We found no differences in behavioural traits between hamsters of different winter phenotypes, but the seasonal increase in activity was lowest in full responders indicating their lower behavioural flexibility than partial responders and nonresponders. The same was true for BMR. While nonresponders and partial responders increased their BMR from summer to winter, full responders did not change it. We argue that different winter phenotypes are maintained in the population because they could be beneficial under different environmental conditions. We also suggest that within a population there is a continuum of winter phenotypes, which is not related to differences in animal personalities. This continuum allows for population maintenance despite environmental conditions changing over short and long timescales.

Don't poke the bear: using tracking data to quantify behavioural syndromes in elusive wildlife

Animal personality traits and the emergence of behavioural syndromes, i.e. between-individual correlation of behaviours, are commonly quantified from behavioural observations in controlled environments. Subjecting large and elusive wildlife to controlled test situations is, however, rarely possible, suggesting that ecologists should exploit alternative measures of behaviours for quantifying differences between individuals. Our goal was to test whether movement and space use data can be used to quantify behavioural syndromes in the wild. We quantified six behaviours from GPS and dual motion sensor tracking devices of 46 adult female brown bears followed in southcentral Sweden over the summer and early autumn. As well as daily travel distance, an indicator for activity, and daily displacement, an indicator for exploration, we quantified four behaviours that increase a bear's likelihood of encountering humans and could thus serve as indicators for boldness: diurnality, selection for roads and selection for two open habitat types, bogs and clearcuts, with low lateral cover. We tested (1) whether behaviours showed repeatable between-individual variation (animal personality) and (2) whether behaviours were correlated between individuals and thus formed a behavioural syndrome. Repeatability of behaviours ranged from 0.16 to 0.61 confirming between-individual variation in movement, activity and space use. A multivariate mixed model revealed significant positive correlations between travel distance, displacement and diurnality, suggesting the existence of an activity–exploration and potentially partial boldness syndrome in our bear population. Selection for exposed or human-frequented habitats were uncorrelated with the activity–exploration syndrome and with each other, albeit there was a trend for stronger road avoidance by bears that readily used clearcuts. We show that large tracking data sets can be used to quantify between-individual correlation in spatial behaviours. We suggest that delineating behavioural types from wildlife tracking data will be of increasing interest because of the importance of animal personality for ecological processes, wildlife conservation and human–wildlife coexistence.

Uwagi o sytuacji prawnej zwierzęcia pokrzywdzonego czynem zabronionym w polskim procesie karnym

The article is focused on the issues relating to a legal situation of an animal as a victim of a criminal offense. Currently, according to the rules of criminal procedure, an animal, as an entity, cannot be legally recognised a victim, which significantly lowers efficiency with which its interests can be protected. There are strong moral and pragmatic reasons to grant animals the status of a non-personal carrier of legal rights. Legal personality of animals as victims during a criminal trial should be of only passive nature, allowing recognition of legally-protected interests of the animal.

Description of a personality syndrome in a common and invasive ground beetle (Coleoptera: Carabidae)

Animal personality, defined as consistent differences among individuals in their behaviour, is being increasingly studied as it might lead to a new understanding of the evolution of behaviours. Despite a clear interest in studying personality in a wide range of taxa for comparative analyses, studies on invertebrates are still scarce. Here, we investigated the personality of a ground beetle, Nebria brevicollis, which is widespread in Europe and invasive in North America. We measured seven behavioural traits from an array of three different tests: (i) activity and exploration related traits; (ii) reaction to a threat, and (iii) phototaxis. The repeatability was tested by measuring all behaviours twice, on different days. All behavioural traits were consistent through time, highlighting the presence of personality in the beetle. In addition, we analysed the relationship between the different traits and highlighted two clusters of behaviours (behavioural syndrome), one grouping activity, exploration and boldness traits, and a second one consisting of responses to a threat. This study is the first to our knowledge to provide evidence for personality dimensions within the vast group of the Carabidae. It also constitutes a preliminary step in the experimental investigation of the importance of animal personality in invasive species.

Personality and plasticity in neophobia levels vary with anthropogenic disturbance but not toxic metal exposure in urban great tits: Urban disturbance, metal pollution and neophobia

Animal personalities, as defined by repeatable among individual differences in behavior, can vary across urbanization gradients. However, how urbanization affects personalities remains incompletely understood, especially because different urban stressors could affect personality traits in opposing ways, whereas most previous studies have considered only one urban disturbance factor. For instance, novel habitat features could favor reduced neophobia, whereas exposure to pollutants could increase risk sensitivity through neurotoxic or hormonal effects. To address this contingency, we studied object neophobia in four urban populations of great tits (Parus major) that vary in exposure to metal pollution and anthropogenic disturbance, as quantified by proximity to roads and pathways. We measured the return latency of incubating females when flushed from the nest and presented with up to two different novel objects, allowing quantification of behavioral repeatability and plasticity. To separate neophobia from sensitivity to disturbance, we also conducted baseline trials, in which females were flushed but no object was presented. We additionally measured exploration behavior and aggression (hissing) during nest defense, to explore whether suites of behaviors covary with urbanization, and examined whether neophobia affects reproductive success. Sensitivity to disturbance and neophobia were repeatable, and thus represent personality traits. Moreover, females occupying territories near roads and pathways had shorter return latencies during novel object but not baseline trials, suggesting a specific reduction in neophobia in disturbed areas. Plasticity in neophobia also increased with disturbance level. In contrast, metal exposure did not affect neophobia or sensitivity to disturbance, despite negatively correlating with exploration behavior. Neophobia correlated with exploration behavior, but not aggression or reproductive success. Results suggest that shifts in personality types in urbanized areas might involve specific reductions in neophobia, rather than general reductions in sensitivity to disturbance, and unexpectedly indicate no effect of toxic metals on risk sensitivity.

Personality influences habituation behaviour in ungulates

The habituation of wildlife to humans is a growing global problem that damages ecological integrity and threatens public safety, but the behavioural processes underlying habituation have rarely been explicitly tested in large animals. These processes are also likely influenced by animal personality. I used three personality traits to delineate a gradient of “shy” to “bold” personality types in captive elk (Cervus canadensis). I then attempted to habituate elk using either food attractants paired with inactive human presence, or with human approaches but no food attractants. Both food and approach treatments significantly reduced elk wariness, as measured by mean flight response distances, while elk in a control pen showed no change. During approach treatments bolder elk showed significantly larger reductions in wariness than shyer elk, but personality had no influence on wariness reductions after food conditioning. My results demonstrate that habituation can be proactive, whereby animals overcome wariness as a way to reap rewards, but can also be reactive, whereby animals can be forced to habituate through the repeated exposure to negative stimuli to which wariness responses are energetically costly. I showed that changes in optimality decisions surrounding risk and reward are influenced by the personalities of individual animals.

Experimental manipulation of monoamine levels alters personality in crickets

Animal personality has been described in a range of species with ecological and evolutionary consequences. Factors shaping and maintaining variation in personality are not fully understood, but monoaminergic systems are consistently linked to personality variation. We experimentally explored how personality was influenced by alterations in two key monoamine systems: dopamine and serotonin. This was done using ropinirole and fluoxetine, two common human pharmaceuticals. Using the Mediterranean field cricket (Gryllus bimaculatus), we focused on the personality traits activity, exploration, and aggression, with confirmed repeatability in our study. Dopamine manipulations explained little variation in the personality traits investigated, while serotonin manipulation reduced both activity and aggression. Due to limited previous research, we created a dose-response curve for ropinirole, ranging from concentrations measured in surface waters to human therapeutic doses. No ropinirole dose level strongly influenced cricket personality, suggesting our results did not come from a dose mismatch. Our results indicate that the serotonergic system explains more variation in personality than manipulations of the dopaminergic system. Additionally, they suggest that monoamine systems differ across taxa, and confirm the importance of the mode of action of pharmaceuticals in determining their effects on behaviour.

What can human personality psychology learn from behavioral ecology?

Personality research has a long and fruitful history in psychology. In the past 15 years, this topic emerged as an important subfield in behavioral ecology as well. A large amount of empirical data has been gathered, and promising theoretical models have been developed. Despite all of this, there is almost no communication between personality research in humans and the behavioral ecology of animal personality. The aim of this article is to present contemporary research on animal personality and thus, to facilitate its integration into human personality psychology. We describe three major topics in the behavioral ecology of personality: the attempts to explain (a) individual differences in personality, (b) temporal stability of personality traits, and (c) the emergence and stability of behavioral syndromes (correlations between personality traits). In all three topics, we suggest how behavioral ecological research and its conceptual apparatus could be implemented in human personality psychology. We also highlight the importance of the empirical measuring of fitness indicators and the adequate translation of concepts from behavioral ecology to human personality psychology and vice versa. Our analysis shows that behavioral ecology represents a fruitful explanatory and empirical framework with high heuristic potential in explaining key problems of personality. The majority of hypotheses developed in this discipline can be tested in human personality psychology; however, some of them demand complex research designs. (PsycINFO Database Record (c) 2018 APA, all rights reserved).

Populations and personalities.

The question of personality in nonhuman animals has loomed large in the study of animal behavior. This issue's featured article assessed the possibility that different environments generate different patterns of personality. Roy and Bhat (2018) studied common measures of personality in two populations of wild zebrafish, Danio rerio. Roy and Bhat's studies support the hypothesis that personality will depend in part on the populations being studied and the environmental variation experienced by individuals in those populations. Populations differing in their exposure to predation should be expected to differ in their propensity to engage in risky behavior (like foraging or courtship) in the context of cues and signals of predators. Beyond this important finding, though, Roy and Bhat (2018) found that higher, as opposed to lower, predation pressure seems to be associated with lower levels of intra- and interindividual variability in boldness-related behavior. Key next steps proposed by the authors include experimental studies aimed at determining the individual effects of variation in predation, water-flow, and food resources on boldness and aggression in these populations, including multiple generations and replicates of each sampled population. (PsycINFO Database Record (c) 2018 APA, all rights reserved).

The EGA+GNM framework: An integrative approach to modelling behavioural syndromes

Behavioural syndromes refer to correlated suites of behavioural traits exhibiting consistent among‐individual variation, i.e. personality. Factor analysis (FA) is currently the dominant method for modelling behavioural syndromes in humans and animals. Although FA is useful for inferring the latent causes underlying trait correlations, it does not account for the pairwise behavioural interactions that also contribute to syndrome structure. Given that latent factors and pairwise interactions are likely ubiquitous causes of trait covariation, both should be modelled simultaneously. Currently, however, behavioural ecologists lack an integrative framework for describing and inferring such behavioural syndromes. Generalized network modelling (GNM), representing an integration of FA and Gaussian graphical modelling (GGM), meets this challenge. We provide a theoretical introduction to GNM as well as a method for detecting latent factors in GGMs called exploratory graph analysis (EGA). We then propose the novel EGA+GNM framework for modelling multiple sources of trait correlations and ensuring more robust causal inferences. To empirically demonstrate the utility of this framework, we compare models derived from EGA+GNM and FA using observational measures of social and arousal behaviour in common marmosets Callithrix jacchus. Using information‐theoretic model comparison, we find support for EGA+GNM models compared to models generated by FA. Two EGA+GNM models suggest that while latent factors contribute to the emergence of clustered sociability and arousal behaviours, correlations among these traits may also be partially explained by pairwise interactions. Additionally, these behavioural clusters are hypothesized to be causally linked by a positive pairwise interaction between allogrooming and activity level. These results support our claim that EGA+GNM provides a superior and integrative framework for describing behavioural syndromes. Consequently, by simultaneously modelling both latent factors and pairwise interactions, behavioural ecologists can better understand the evolutionary causes and consequences of animal personality. A formal overview of the EGA+GNM framework and a R tutorial demonstrating its application are provided in the electronic Supporting Information .

On the usage of single measurements in behavioural ecology research on individual differences

Since the early 21st century, behavioural ecologists have increasingly focused on the ecology and evolution of repeatable individual differences in behaviour (aka ‘animal personality’). More and more studies have investigated correlations between behaviour(s) and other phenotypic traits, thereby seeking to understand among-individual variation in behaviour from either a proximate or an ultimate perspective. Statistically, such studies require the estimation of among-individual correlations, necessitating study designs where suites of labile traits are repeatedly assayed. Most published studies, by contrast, instead assume that among-individual correlations can be approximated using data of suites of phenotypic traits measured only once. Such studies take an ‘individual gambit’ as they assume that phenotypic correlations between two traits measured once match among-individual correlations. A literature survey shows that this assumption was made in 62% of empirical studies; this is a worrying trend as a mismatch between the research question and the study (or statistical) design can lead to biased conclusions about biological patterns. In this paper we use a visual approach to illustrate these concerns for a broad audience, thereby complementing previous papers using a jargon more suitable for the statistically oriented. We thereby seek to reiterate the notion that reliable answers to any scientific question require specific types of data. While this commentary underlines the importance of spelling out key assumptions in discussions of (suboptimal) data in scientific papers on individuality, our main message is that researchers should typically be able to avoid publishing studies with conclusions heavily hinging on unverifiable assumptions. This is because researchers normally have the freedom to decide a priori to focus their research towards questions for which appropriate data can arguably be collected. Doing so would greatly facilitate our ability to robustly address key questions of biological interest, such as the ecology and evolution of individuality.

Parasite infection and host personality: Glugea-infected three-spined sticklebacks are more social

The existence of animal personality is now well-documented, although the causes and consequences of this phenomenon are still largely unclear. Parasite infection can have pervasive effects on hosts, including altering host behaviour, and may thus contribute to differences in host personality. We investigated the relationship between the three-spined stickleback and its common parasite Glugea anomala, with focus on differences in host personality. Naturally infected and uninfected individuals were assayed for the five personality traits activity, exploration, boldness, sociability, and aggression. If infected fish behaved differently from uninfected, to benefit this parasite with horizontal transmission, we predicted behaviour increasing interactions with other sticklebacks to increase. Infection status explained differences in host personality. Specifically, Glugea-infected individuals were more social than uninfected fish. This confirms a link between parasite infection and host behaviour, and a relationship which may improve the horizontal transmission of Glugea. However, future studies need to establish the consequences of this for the parasite, and the causality of the parasite-host personality relationship.Significance statementParasite infection that alters host behaviour could be a possible avenue of research into the causes of animal personality. We studied the link between infection and personality using the three-spined stickleback and its parasite Glugea anomala. We predicted that infected individuals would be more prone to interact with other sticklebacks, since this would improve transmission of this parasite. The personality of uninfected and naturally infected fish was measured and we observed that Glugea-infected sticklebacks were more social. Our results confirm a link between parasitism and variation in host personality.

Effects of acclimatisation on behavioural repeatability in two behaviour assays of the guppy Poecilia reticulata

Establishing behavioural repeatability is important in animal personality research; however, a range of factors can influence repeatability. Experimental design, particularly acclimation time, is important in managing a subject’s stress prior to the onset of behavioural observations. Acclimatisation also ensures we capture “normal” behaviour and promotes consistency in the subject’s responses between observations. The importance of acclimatisation prior to an assay is widely recognised by animal researchers; however, acclimation time varies dramatically across personality studies. Here, we investigated the effects of acclimatisation time on the repeatability of activity and emergence behaviour in feral and domestic populations of lab-reared guppy, Poecilia reticulata. Contrary with expectations and previous findings, we found highest repeatability in guppy activity levels after 2 h of acclimation to the test arena. In the emergence assay, fish exposed to 10 min of acclimatisation showed highest repeatability; however, all acclimation periods produced high repeatability, suggesting that the emergence assay generates robust behavioural responses irrespective of acclimation time. The outcomes were broadly consistent across both populations. These results show that methodology can impact the findings of animal personality research and needs to be considered carefully for each assay. We recommend that researchers investigate appropriate acclimatisation times for their study species prior to commencing research. Animal personality is individual differences in behaviour that are maintained through time and across contexts. Thus, demonstrating the repeatability of behavioural differences between individuals is imperative to establishing animal personality. To estimate repeatability, individuals are assessed multiple times on the same task to ensure there are consistent differences between individuals. When carrying out repeated observations, acclimatisation time should be considered to minimise stress levels of an animal prior to the behavioural assay. We assessed a range of acclimation times on emergence and activity behaviour in two populations of guppies. While individual variation in emergence behaviour was repeatable across a range of acclimation times, activity levels in guppies became significantly more repeatable after 2 h of acclimatisation. These results show that considering proper acclimation time is important when performing behavioural experiments and should be properly calibrated by researchers prior to conducting personality research.

'Love at first sight': The effect of personality and colouration patterns in the reproductive success of zebrafish (Danio rerio).

Individual differences in animal personality and external appearance such as colouration patterns have both been extensively studied separately. A significant body of research has explored many of pertinent ecological and biological aspects that can be affected by them and their impact upon fitness. Currently little is known about how both factors interact and their effect on reproductive success. In this study, we evaluated two major parameters contributing to the fitness of the species: reproduction and offspring survival. We selected two different phenotypes of the zebrafish (Danio rerio) selected by their colouration patterns: phenotype 1) named Wild type, UAB line (WT-UAB) with a homogeneous colouration pattern (clear and defined lateral stripes) and phenotype 2) Wild type indefinite (WT-I) had a heterogeneous colouration pattern and different degrees of lateral stripe definition. All animals were also screened for personality. We then compared their reproductive success (spawning rate) and offspring survival at different stages, from egg to larvae, and for 2 successive generations (parental generation was G0; First and second generations were G1 and G2 respectively). Our results show that personality traits were the main source of variability between the fitness components measured: both personalities had similar total numbers of eggs spawned but proactive animals, for both colour phenotypes, had higher reproductive success. This was reflected in a higher percentage of spawning viability at 1day post fertilization (dpf), higher total survival and growth rates at larval stages. Proactive phenotypes from WT-UAB population had a higher overall fitness in comparison to the other phenotypes studied. Our findings imply that fitness of this species when kept under similar husbandry conditions is significantly influenced by parental personality and not by their external appearance. Under these conditions the reproductive success is enhanced. The implications of this study are important for zebrafish breeding and husbandry in captivity and are relevant toward understanding the underlying drivers of trait selection in natural environments.

Independence between coping style and stress reactivity in plateau pika

The concept of coping style represents the way individual animals react to a stressful situation, both behaviourally and neurophysiologically. Over the last decades coping style has been linked to the development of research on animal personality. Based on this concept, we should find a proactive-reactive continuum in animal populations, with proactive individuals being fast explorer, bold, aggressive, and show high sympathetic reactivity (higher heart rate), as well as low hypothalamus-pituitary-adrenocortical (PHA) axis reactivity to external stressor (higher plasma glucocorticoid level). At the other extreme, shy, lowly aggressive, reactive individuals should be slow in their exploration, and show a low sympathetic reactivity and a high HPA axis reactivity. However, a recent two-tier model proposed that coping style and stress reactivity should be independent of each other. In this study, we tested the two-tier model in a wild plateau pika (Ochotona curzoniae) population on the Tibetan Plateau, by quantifying the associations between several behavioural and physiological traits at the among- and within-individual levels. We repeatedly measured exploration, docility, boldness, heart rate and plasma cortisol concentration in individuals between April and September of 2013. All traits tested were repeatable. At the among-individual level, all behavioural traits were correlated with each other and with heart rate, but were independent of both basal level and variation of plasma cortisol concentration. Most correlations were negligible at the within-individual level. In support of the two-tier model, these results suggest that coping style (i.e. behaviour and heart rate associations) is independent of stress reactivity (i.e. glucocorticoid reactivity) in that species.

Innovation as part of a wider behavioural syndrome in the guppy: The effect of sex and body size

AbstractRecent work on animal personalities has shown that individuals within populations often differ consistently in various types of behaviour and that many of these behaviours correlate among individuals to form behavioural syndromes. Individuals of certain species have also been shown to differ in their rate of behavioural innovation in arriving at novel solutions to new and existing problems (e.g., mazes, novel foods). Here, we investigate whether behaviours traditionally studied in personality research are correlated with individual rates of innovation as part of a wider behavioural syndrome. Guppies (Poecilia reticulata) of both sexes from three different wild population sources were assessed: (a) exploration of an open area; (b) speed through a three‐dimensional maze; (c) investigation of a novel object; and (d) attraction to a novel food. The covariance structure (syndrome structure) was examined using structural equation modelling. The best model separated behaviours relating to activity in all contexts from rates of exploration/investigation and innovation. Innovative behaviour (utilizing new food and moving through a novel area) in these fish therefore forms part of the same syndrome as the traditional shy‐bold continuum (exploration of an open area and investigation of a novel object) found in many animal personality studies. There were no clear differences in innovation or syndrome structure between the sexes, or between the three different populations. However, body size was implicated as part of the behavioural syndrome structure, and because body size is highly correlated with age in guppies, this suggests that individual behavioural differences in personality/innovation in guppies may largely be driven by developmental state.