It is widely documented that non-human organisms express individual differences in behavioural patterns. For example individuals can be categorised as bold or shy and when these individual behavioural differences are consistent through time, they are termed behavioural types (BTs). In recent years research has identified that BTs often correlate across contexts/situations and these correlations are referred to as behavioural syndromes. Behavioural types and syndromes (i.e. personality) have also been implicated as major factors shaping population dynamics and the ability to buffer environmental disturbance. Recent theoretical predictions have proposed that BT variation may be underpinned by life-history strategies; however, these predictions have been little studied to date. Moreover, little research has focused upon environmental influences and the ontogeny of personality. In this thesis I use the Mangrove killifish (Kryptolebias marmoratus), a naturally occurring clonal vertebrate, as a model organism. This species presents a powerful tool providing the ability to replicate within and between isogenic genotypes in a controlled manner. Moreover the natural clonality expressed by this species permits environmental effects upon BT plasticity and BT-life-history interactions to be investigated within a developmental framework. In chapter 2, I present microsatellite genotyping results which show that the founding individuals used to propagate a laboratory population at The University of Exeter represent 20 genetically distinct homozygous genotypes. I additionally address five research questions exploring genotypic, environmental, and developmental effects upon three commonly studied BTs (exploration, boldness and aggression): Firstly; I ask do adult hermaphrodite and secondary males exhibit personality i.e. repeatable BT expression? In chapter 3, I present results showing that both of the sexes express short term personality. Moreover, I show that that genotype is an important factor influencing BTs expressed, regardless of sex, indicating underlying genetic control. Secondly I ask; does genotype level life-history variation underpin personality trait variation during ontogeny? In chapter 4, I show considerable developmental plasticity in behavioural expression between genotypes but not life-history and I find limited behaviour-life-history relationships during development. Thirdly I ask; does the rearing environment influence life-history and behavioural plasticity? In chapter 5, I show that in comparison to a control treatment, the presence of conspecifics during ontogeny results in an average reduction in behavioural scores; however, life-history was unaffected. In addition, I show that development in a low food environment lowered average exploration and growth rate but had no effect on boldness or aggression. Furthermore, fish exposed to a predation risk simulation during ontogeny exhibited similar behavioural scores as the control, yet this treatment generated BTs i.e. personality. My fourth question asks; does the parental rearing environment (utilised in chapter 5) influence behavioural expression in the next generation? In chapter 6, I show that transgeneratonal effects of each parental rearing environment influenced life-history but had a minimal effect upon behaviour in the next generation. Finally I ask; does kin or familiarity influence plasticity in associations and aggression? In chapter 7, I show that genotypes have the ability to discriminate kin and familiars and modulate aggression and association accordingly. These results support the concept that developmental and environmental induced plasticity may be more important than life-history in shaping behaviour. Furthermore, although adults exhibit personality and genotypic effects appear important, genotype interacts with environmental/experiential influences to differentially shape behavioural plasticity during ontogeny. I suggest that theoretical predictions regarding life-history may be insufficient to explain the complexity of animal personality in this species. I discuss these results within developmental and epigenetic frameworks with reference to the ecological significance of these patterns within this species and the animal kingdom as a whole.

Consistent between-individual differences in behaviour (termed “animal personality”) may be driven by adaptive differences in behavioural and physiological life-history traits. The Pace of Life Syndrome (POLS) hypothesis predicts a suit of correlations between those life-history traits along a fast-slow continuum. Therefore, according to the POLS, individuals that are fast-paced would be bolder, more explorative, show high growth-rates, lower immunity and a higher metabolic rate. A mechanistic link between such traits could also explain variation in cognitive traits, where bold individuals are faster at a given task but pay less attention to external cues and therefore make decisions less accurately. Here, I tested the POLS hypothesis focusing on between and within-individual variance in boldness, metabolic rate (MR), cognitive performance (as decision-making performance) and exploration in the hermit crab Pagurus bernhardus. In addition, I also investigated the potential role of anthropogenic disturbances (constant light exposure) as a driver of between and within-individual variation in boldness. Hermit crabs demonstrated consistent between-individual differences in boldness and exploration, providing evidence for the presence of animal personality. However, variation between individuals in boldness, exploration and cognitive performance were not underpinned by variation in MR. Although there were no between-individual correlations among MR and behaviour, MR did co-vary with within-individual variance in boldness. My results indicate that less predictable hermit crabs, on average, have a higher MR during startle responses compared with those that are relatively consistent in their behaviour. Boldness was positively correlated with exploration rate, indicating that more explorative were also bolder, as well as cognitive performance, as bold individuals had a better performance than shy. Finally, constant light exposure is likely to modify hermit crab personality and physiology. Hermit crabs kept under a constant light regime were less bold and had a higher metabolic rate, than when kept under standard light and dark regime, indicating possible effects light pollution in this species. These results only partially support the POLS hypothesis.

Animal personality is found in a wide range of taxa, yet our knowledge of what maintains consistent among-individual variation in behaviour is still incomplete. Many personality traits are associated with fitness, leading to the expectation that, under selection, genetic (and among-individual) variation will be eroded over time. Several adaptive models have been developed in order to explain this maintenance of variation. These include state-dependence, state-behaviour feedback loops, life-history and behavioural coadaptation and the Pace of Life syndrome. These models represent good starting points for thinking about what drives and maintains among-individual variation in behaviour, and while empirical support for these models is mixed, one thing they do have in common is the assumption of a significant genetic basis underpinning personality traits. Significant heritability is required for an evolutionary response to selection and for among-individual variation to be adaptive. The univariate estimates of heritability for personality traits that are growing in the literature, while useful, are likely insufficient to predict how personality traits will respond to selection. This thesis uses the Trinidadian guppy, Poecilia reticulata, and other species to explore patterns of among-individual and genetic variation in personality traits, advocating the benefits of using multivariate perspectives throughout. Firstly, the among-individual covariance structure between measures of boldness, growth and metabolic rate are estimated in a test of the Pace of Life syndrome. Secondly, an appraisal of the relative strength of maternal and genetic effects on offspring personality and how it changes over ontogeny. Next, a comprehensive treatment of sexual dimorphism in behaviour and size followed by analysis of genotype-by-sex interactions using both univariate and multivariate methods. Finally, a comparative analysis of personality in 7 species of small fish, identifying the main axis of among-individual variation from a single assay in each and quantifying the phylogenetic signal.

The widespread use of pharmaceutics raises an anthropogenic issue in natural environment. Selective serotonin reuptake inhibitors (SSRI) used as antidepressants, pass through most wastewater treatment plants and enter natural waters.  Their impact on personality of aquatic animals is poorly investigated, especially in invertebrates. In the current study, the impact of fluoxetine (an SSRI) on animal personality was investigated in the freshwater isopod Asellus aquaticus. To investigate responses, isopods were exposed for 1 day to fluoxetine of 10 ng L-1. Boldness, exploration, activity and escape behaviour (running and freezing) were tested on male and female isopods of two phenotypes of pigmentation (dark and light). The isopods showed consistency of behaviour responses in assays; one of the prerequisites for the existence of personality traits. Fluoxetine exposure reduced activity level, but had no effect on the other personality traits measured. This study thus provides some support for the idea that an environmentally relevant concentration of fluoxetine affects personality in A. aquaticus.

Two crucial issues related to personality in non-human animals have been identified: firstly, the underlying 'causes' of personality and,secondly, the stability of behavioural repertoires (essentially the defining feature of personality) have both been the subject of long-standing debate. This thesis is focused on investigating stable inter- and intra- individual differences in the behaviour of wildcaught bank voles, Myodes glareolus (that varied according to mtDNA type), and in common voles, Microtus arvalis. The first study, using wild voles, revealed empirical evidence about the effects of sex and mtDNA type on individual differences in basal metabolic rate and in behaviour in the open field which provides measures of approach and avoidance (here, generically termed 'proactivity') and which relate to several theoretical conceptualisations of animal personality. The second study demonstrated the presence of stable individual differences in reactions to exposure to open field test and radial maze in common voles, which were shaped by the social environment and in turn, related to cognitive efficiency. The same species was used in the third study documenting the distinct temporal patterns of behavioural plasticity that manifested over repeated exposures to the open field test. We suggest that this distinct temporal patterning in habituation, whilst it varied over time, was predictable in nature and therefore a reflection of a stable underlying personality. To conclude, this body of thesis work draws together a number of influencing factors, and considers their contribution to animal personality.

abstract: For interspecific mutualisms, the behavior of one partner can influence the fitness of the other, especially in the case of symbiotic mutualisms where partners live in close physical association for much of their lives. Behavioral effects on fitness may be particularly important if either species in these long-term relationships displays personality. Animal personality is defined as repeatable individual differences in behavior, and how correlations among these consistent traits are structured is termed behavioral syndromes. Animal personality has been broadly documented across the animal kingdom but is poorly understood in the context of mutualisms. My dissertation focuses on the structure, causes, and consequences of collective personality in Azteca constructor colonies that live in Cecropia trees, one of the most successful and prominent mutualisms of the neotropics. These pioneer plants provide hollow internodes for nesting and nutrient-rich food bodies; in return, the ants provide protection from herbivores and encroaching vines. I first explored the structure of the behavioral syndrome by testing the consistency and correlation of colony-level behavioral traits under natural conditions in the field. Traits were both consistent within colonies and correlated among colonies revealing a behavioral syndrome along a docile-aggressive axis. Host plants of more active, aggressive colonies had less leaf damage, suggesting a link between a colony personality and host plant health. I then studied how aspects of colony sociometry are intertwined with their host plants by assessing the relationship among plant growth, colony growth, colony structure, ant morphology, and colony personality. Colony personality was independent of host plant measures like tree size, age, volume. Finally, I tested how colony personality influenced by soil nutrients by assessing personality in the field and transferring colonies to plants the greenhouse under different soil nutrient treatments. Personality was correlated with soil nutrients in the field but was not influenced by soil nutrient treatment in the greenhouse. This suggests that soil nutrients interact with other factors in the environment to structure personality. This dissertation demonstrates that colony personality is an ecologically relevant phenomenon and an important consideration for mutualism dynamics. / Dissertation/Thesis / Doctoral Dissertation Biology 2018

Animals exhibit a wide variety of social behaviours that are shaped by the external group social structure. Thus, understanding social behaviours and processes requires examining the individual social associations that form the basis of a group’s social network. The first objective of this thesis was to assess the consistency of social position within wild networks of black-capped chickadees (Poecile atricapillus) and to evaluate the effects of individual behavioural traits (exploratory personality and social dominance) on network position. Intra-annual social position was found to be repeatable and centrality increased with dominance rank, suggesting that dominant individuals occupy more central positions. The second objective of this thesis was to evaluate how network position and individual traits influence the transmission of social information through groups; the use of information acquired by other group members is expected to be an important benefit to group living. Social information regarding the location of novel foraging patches was observed to be transmitted through all eight chickadee groups. The rate of information transmission was found to be positively associated with dominance rank, but was not influenced by exploratory personality, indicating that dominant individuals may have greater access to social information than more subordinate individuals. The final aim of this thesis was to assess if social information transmission varied between urban and rural environments, as increased resource variability in more rural sites was expected to lead to higher reliance on social foraging cues. However, no effect of level of urbanisation was detected on the transmission of social information regarding novel food sources, which may indicate a habitat-independent strategy of social information use in chickadees. In general the results from this thesis indicate the importance of dominance status on individuals’ position within a social group, which can lead to differential exposure to social processes, such as social information transmission.

Animal personality is a fairly new branch of biology and has been defined as a difference in behaviour between individuals that is relatively consistent across time and/or context. What researchers now are interested in is to find out what it is that creates and maintains this relatively consistent difference between individuals. One possibility is the stress hormone, corticosterone. I have in this report summed up some of the available studies regarding animal personality and its possible correlation to corticosterone. The personality traits that have been reviewed in this report are boldness, exploration, activity, aggressiveness and sociability. The result of these studies show that boldness have both a negative and a positive correlation; exploration showed different correlations between studies; aggressiveness showed different correlation between different animal types and sociability showed both a negative and none correlations. The only one that I could not determent the correlation for was activity. The research regarding animal personality and corticosterone can be of use when looking at animal welfare and how stress affects different individuals. This can give us a direction in our work to reduce stress for animals in research facilities and food production.

No description available.

Infectious disease is a ubiquitous aspect of life on earth; however, parasites and pathogens are not distributed equally among individual hosts. Due to its ability to shape the way that individuals interact with other potential hosts and the environment, behavior is one of the most salient ways through which host biology varies in the context of disease. Variation in animal behavior can impact both transmission and the extent of a host's pathogen acquisition, and thus can have important consequences for infectious disease dynamics. Additionally, in this world of rapid urbanization where landscapes and wildlife resources are being altered, it is important to understand the ways in which human activity impact wildlife behavior, and in turn, disease dynamics. Here, we used both observational and experimental studies in field and laboratory settings to investigate the relationships among host behavior and physiology, anthropogenic food sources, and disease transmission in a natural host-pathogen system. First, we examined the relationship between house finch (Haemorhous mexicanus) stress physiology, exploratory behaviors, and social behaviors in the wild. We provided evidence that more exploratory house finches interact with more individuals in the wild, and have higher baseline concentrations of circulating stress hormones. Next, we found evidence that the amount of time spent on bird feeders drives both the acquisition and transmission of the bacterial pathogen Mycoplasma gallisepticum (Mg), indicating that variation in host foraging behavior has important transmission consequences in this system. Lastly, we found that the density of bird feeders available to house finches predicts the extent of Mg transmission in captivity. Taken together, these results highlight the important role that behavioral heterogeneity can play in the acquisition and spread of pathogens, as well as the potential impacts of human behavior on wildlife disease dynamics. Future work should seek to identify specific physiological mechanisms driving Mg acquisition and transmission as they relate to variation in host behavior, and the ways in which bird feeders impact disease-relevant behaviors in the wild. / Ph. D. / Infectious disease impacts almost every living creature on earth; however, some individuals are more likely to become sick and spread disease than others. Animal behavior can strongly influence disease dynamics due to its ability to shape the way that individuals interact with one another and the environment. Behavior can impact an individual’s likelihood of both acquiring and spreading disease, and thus can have important consequences for disease outbreaks. Additionally, as urban areas are expanding, it is important to understand the ways in which human activity impact wildlife behavior, and in turn, disease dynamics. Through both laboratory and field studies, we investigate the relationships among host behavior and physiology, human-related food sources, and disease transmission in a natural wildlife disease system. First, we examined the relationships between stress hormones, exploratory behaviors, and social behaviors of house finches, a common songbird. We provided evidence that more exploratory house finches interact with more individuals in the wild, and have higher concentrations of stress hormones. Next, we found evidence that the amount of time that house finches spend on bird feeders drives both the likelihood of acquiring and spreading conjunctivitis (=pink eye). This means that certain individuals are more likely to get sick and pass the disease on to others than other individuals are. Lastly, we found that when the density of bird feeders available to house finches is high, we see more disease transmission. Taken together, these 5 results highlight the important role that variation in behavior can play in acquiring and spreading disease, as well as the potential impacts of human behavior on wildlife health.