In recent years there have been efforts to assess associations between personality, longevity and well-being in nonhuman primates. Currently, findings indicate that, as in humans, personality traits such as extraversion are associated with both higher well-being (in monkeys and apes) and longevity (in gorillas). Why certain traits seem to have a protective effect is not yet well understood. One hypothesis is that more extraverted individuals rely on the company of others to alleviate stress, and thus mediate physiological stressors, increasing potential life span. Individual differences in social behaviour are therefore an important consideration for increasing our understanding of the protective effects of personality traits. The role of personality in social interactions and well-being is the main focus of this thesis. In Chapter 2, I assess personality and well-being in two species of New World monkey - common (Saimiri sciureus) and Bolivian squirrel monkeys (Saimiri boliviensis) - for which these associations have not previously been studied. I assess differences in personality trait structure between the two species, and compare them to a close relative, Sapajus apella (brown capuchins). I also correlate personality with well-being. Results show that both squirrel monkey species are similar in personality structure, but Bolivian squirrel monkeys share more similar traits with brown capuchins than common squirrel monkeys do. Well-being is associated with low Neuroticism and high Openness. These comparisons inform our understanding of the phylogeny of personality traits, as well as the ancestral links between personality and well-being. In Chapter 3 I focus on examining individual differences in chimpanzee (Pan troglodytes) traits, through the use of previously collected personality data, which may reflect something akin to autism in nonhuman primates. In Chapter 4 I examine behavioural correlates of these traits, and assess personality in relation to behaviour. Results indicate that personality is a stronger predictor of individual differences in social behaviour than the scale measuring autism-like traits. Continuing with a focus in chimpanzees, in Chapter 5 I examine whether personality predicts how individual chimpanzees perceive emotion in conspecifics, using both behavioural and experimental data. Findings show that individuals differ in their attention and arousal in response to emotions in others, and that personality plays a role in these responses. I also report different ‘levels’ of response indicative of separate arousal and attention based processes. This is an understudied but important area of research that might help to elucidate differences in coping with stressful situations in a group environment. In Chapter 6 I shift from a focus of personality as a predictor of response, to potential signals of personality, by examining personality correlates of facial morphology in brown capuchins, Sapajus apella. Results indicate that face width is associated with higher Assertiveness, whilst lower face height is associated with higher Neuroticism/lower Attentiveness. To assess the theory that these associations may act as social cues, such as signals of status or mate quality, in Chapter 7 I assess whether capuchins perceive differences in face width of conspecifics by measuring response to facial images. Results suggest that capuchins do not differ between wide and narrow faces. I discuss the possibility that perception of these associations may be dependent on other variables such as age or knowledge of the signal receiver. Overall, this thesis takes a broad approach to understanding personality, by examining its role in social interactions, perception of others and well-being. These findings are discussed in light of both evolutionary theory and potential benefits to welfare.

Social behaviours have been widely studied in behavioural economics and psychology. However, the origins of these behaviours in the brain are poorly understood. In this dissertation I will discuss two main avenues of study which constituted separate projects during my PhD candidacy. The first section contains experiments in which I collaborated with Dr Raymundo Báez-Mendoza on the topic of inequity. The second part includes a study on coordination and cooperation behaviour in macaques. Inequity is a concept ubiquitous in daily life. It is the difference between one’s own reward and that of another. There have been several studies that have suggested inequity affects brain activity. However, few studies have touched upon how this parameter is incorporated in neuronal activity. In the experiments that will be described here, monkeys (Macaca mulatta) performed actions to obtain rewards for both themselves and another. The level of inequity in these rewards was manipulated by varying the magnitude of own and other’s rewards. We then proceeded to study neuronal activity by means of single neuron recordings in the striatum of two macaques. We found that inequity modulated task related activity in about 32% of recorded striatal neurons. In addition to this study on inequity we also recorded some sessions in which one of the animals made choices with varying rewards for self and other. From these results, I attempted to characterise behaviour with regards to own reward and inequity in choice situations. Inequity has been considered a contributing factor in explaining cooperation behaviour. Coordination and cooperation are important and frequently observed behaviours. To study coordination and cooperation, I designed an experiment in which the combination of two monkeys’ choices determined the rewards for both animals. In this dissertation I attempt to address how the animals perform combined choices (playing together vs. alone) as well as the nature of their behaviour (e.g. pro-social vs. self-interested). The aim of this work was to characterise what type of information the animals use to solve these tasks. This is vital if one is to study these concepts in the brain using macaques as a model. In summary, this work contributes to a better understanding of social behaviour and provides an example of how this social behaviour is computed in the brain.

Binge alcohol drinking is a major public health concern world wide and its occurrence is rising among young adults. Using animal and human subjects, this thesis evaluates the impact of binge drinking during a time of neurodevelopment on aspects of impulse control, and studies the potential of addressing a molecular target, the μ-opioid receptor, to alleviate elevated impulsive-like behaviour. First, the nature of impulsivity is described in a review paper. We demonstrate the suitability of the Five-Choice Serial Reaction Time Task (5-CSRTT) for measuring one facet of impulsivity, waiting impulsivity, in mice. Bridging the animal and human laboratories, we developed a novel human analogue of the 5-CSRTT (paper 2). Elevated impulsive behaviour was detected in both young human binge drinkers and in an ethanol-preferring strain of mice, suggesting impulsivity to occur as a prelude to heavy alcohol use. In a second approach (paper 3), we studied the long term effects of intermittent alcohol exposure using a mouse model of adolescent binge drinking. We revealed disrupted impulsive behaviour in adulthood in two different inbred strains, which differ in baseline impulsivity and ethanol drinking patterns, indicating that impulsivity is also a consequence of ethanol exposure. In paper 4 we studied the ability of an opioid antagonist to improve top-down control of impulsive behaviour. Consilience between species and paradigms will need to be further addressed in future studies, but antagonising μ-opioid systems may aid in preventing binge drinking by facilitating inhibitory control mechanisms. Collectively, from animal and human evidence, this thesis will argue that exaggerated impulsivity may result from repeated ethanol withdrawal in adolescence as well as being a pre-existing endophenotype contributing to adolescent binge drinking. Disentangling such a relationship may help delineate new lines of intervention for at-risk individuals.

Chronic wasting disease (CWD) has been a known threat to Saskatchewans wild cervid populations for more than a decade. As host movements can affect the spread of a disease across the landscape, disease models and management strategies should incorporate information regarding movement patterns of the host population in question. I used radio telemetry to study mule deer (<i>Odocoileus hemionus</i>) captured between 2006 and 2008 in a CWD-endemic region of southern Saskatchewan. Using location data from 152 individuals, I investigated home range size and patterns of direct and indirect contact (measured using proximity and shared space use) in relation to sex, habitat, and landscape structure. <p>Home ranges (95% fixed kernel) of GPS-collared deer in this study averaged 21.4 km² (n = 94). Male home ranges (mean = 29.5 km², n = 56) were larger than those of females (mean = 16.1 km², n = 38), which could have implications for CWD prevalence differences between sexes. Of the landscape variables tested, topographic ruggedness was inversely related to home range size and Shannons diversity (a measure of both habitat richness and evenness) was positively related to home range size. <p>Potential direct contact events were identified when two deer were located within 25 m of each other at the same point in time. These events occurred more often between February and April, agreeing with the tendency of mule deer to aggregate into large groups during the late winter months, and suggesting that this may be an important time period for disease transmission. Contact also occurred more than expected in cropland, whereas areas of shared use occurred more than expected in grassland, shrub/wood habitat, and rugged terrain. Smaller home ranges and greater degree of shared space use within areas of rough topography may lead to greater risk of environmental contamination with the infectious CWD agent in these areas. In contrast, the relationship between cropland and probability of direct contact may imply greater risk of direct CWD transmission between deer occupying this habitat. <p>These results identify connections between particular landscape factors and risk of CWD transmission and will be used, in combination with results of related studies, to develop a model of CWD spread in Saskatchewan. This will in turn aid management agencies in developing methods to more effectively manage the disease and control its movement outside of affected regions.

Chronic wasting disease (CWD) has been a known threat to Saskatchewans wild cervid populations for more than a decade. As host movements can affect the spread of a disease across the landscape, disease models and management strategies should incorporate information regarding movement patterns of the host population in question. I used radio telemetry to study mule deer (<i>Odocoileus hemionus</i>) captured between 2006 and 2008 in a CWD-endemic region of southern Saskatchewan. Using location data from 152 individuals, I investigated home range size and patterns of direct and indirect contact (measured using proximity and shared space use) in relation to sex, habitat, and landscape structure. <p>Home ranges (95% fixed kernel) of GPS-collared deer in this study averaged 21.4 km² (n = 94). Male home ranges (mean = 29.5 km², n = 56) were larger than those of females (mean = 16.1 km², n = 38), which could have implications for CWD prevalence differences between sexes. Of the landscape variables tested, topographic ruggedness was inversely related to home range size and Shannons diversity (a measure of both habitat richness and evenness) was positively related to home range size. <p>Potential direct contact events were identified when two deer were located within 25 m of each other at the same point in time. These events occurred more often between February and April, agreeing with the tendency of mule deer to aggregate into large groups during the late winter months, and suggesting that this may be an important time period for disease transmission. Contact also occurred more than expected in cropland, whereas areas of shared use occurred more than expected in grassland, shrub/wood habitat, and rugged terrain. Smaller home ranges and greater degree of shared space use within areas of rough topography may lead to greater risk of environmental contamination with the infectious CWD agent in these areas. In contrast, the relationship between cropland and probability of direct contact may imply greater risk of direct CWD transmission between deer occupying this habitat. <p>These results identify connections between particular landscape factors and risk of CWD transmission and will be used, in combination with results of related studies, to develop a model of CWD spread in Saskatchewan. This will in turn aid management agencies in developing methods to more effectively manage the disease and control its movement outside of affected regions.

Social support is thought to give animals benefits from social partners, such as improved coping with challenges. The aim of this study was to investigate differences in social support in the red junglefowl (RJF) and a domestic layer strain, the White Leghorn (WL). A runway test consisting of two compartments with unfamiliar and familiar stimulus animals was used to measure social motivation before and after a stressful experience. Total number of test animals was 56 divided into four groups; male and female WL as well as male and female RJF. Results showed that females preferred to stay close to familiar conspecifics after stress treatment. Before stress treatment there was little difference between either sex of WL while RJF males and females chose different zones. Females preferred familiar conspecifics, indicating that they rely more on familiar social stimuli for social support. Males of the two breeds behaved differently towards stimulus animals. WL males showed aggression towards familiar stimulus animals while RJF males directed aggression towards unfamiliar stimulus animals. Indication of sexual behavioural dimorphism was supported while further research is needed in domestication effects on social support in chickens.

Chronic wasting disease (CWD) has been a known threat to Saskatchewan’s wild cervid populations for more than a decade. As host movements can affect the spread of a disease across the landscape, disease models and management strategies should incorporate information regarding movement patterns of the host population in question. I used radio telemetry to study mule deer (Odocoileus hemionus) captured between 2006 and 2008 in a CWD-endemic region of southern Saskatchewan. Using location data from 152 individuals, I investigated home range size and patterns of direct and indirect contact (measured using proximity and shared space use) in relation to sex, habitat, and landscape structure. Home ranges (95% fixed kernel) of GPS-collared deer in this study averaged 21.4 km² (n = 94). Male home ranges (mean = 29.5 km², n = 56) were larger than those of females (mean = 16.1 km², n = 38), which could have implications for CWD prevalence differences between sexes. Of the landscape variables tested, topographic ruggedness was inversely related to home range size and Shannon’s diversity (a measure of both habitat richness and evenness) was positively related to home range size. Potential direct contact events were identified when two deer were located within 25 m of each other at the same point in time. These events occurred more often between February and April, agreeing with the tendency of mule deer to aggregate into large groups during the late winter months, and suggesting that this may be an important time period for disease transmission. Contact also occurred more than expected in cropland, whereas areas of shared use occurred more than expected in grassland, shrub/wood habitat, and rugged terrain. Smaller home ranges and greater degree of shared space use within areas of rough topography may lead to greater risk of environmental contamination with the infectious CWD agent in these areas. In contrast, the relationship between cropland and probability of direct contact may imply greater risk of direct CWD transmission between deer occupying this habitat. These results identify connections between particular landscape factors and risk of CWD transmission and will be used, in combination with results of related studies, to develop a model of CWD spread in Saskatchewan. This will in turn aid management agencies in developing methods to more effectively manage the disease and control its movement outside of affected regions.

The present study examined social status and adult neurogenesis in the naked mole rat. These animals live in large colonies with a strict reproductive dominance hierarchy; one female and 1-3 males breed, while other members are subordinate and reproductively suppressed. We examined whether social status affects doublecortin (DCX; a marker for immature neurons) immunoreactivity in the dentate gyrus, piriform cortex (PCx), and basolateral amygdala (BLA) by comparing breeders to subordinates. We also examined subordinates removed from their colony and paired with opposite- or same-sex conspecifics for 6 months. Breeders had reduced DCX immunoreactivity in all areas, with BLA effects confined to females. Effects of housing condition were region-specific, with higher PCx DCX immunoreactivity observed in opposite- than same-sex paired subordinates regardless of gonadal status. The opposite pattern was observed in the BLA. Future work will clarify whether findings are attributable to status differences in stress, behavioural plasticity, or life stage.

Lic.-avh. Alnarp : Sveriges lantbruksuniv.

Diss. (sammanfattning) Alnarp : Sveriges lantbruksuniversitet, 2004. / Härtill 3 uppsatser.