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A thesis submitted to the Faculty of Science, University of the Witwatersrand, Johannesburg, in fulfilment of the requirements for the degree of Doctor of Philosophy. Johannesburg 2017. / The study of personality has received much attention in recent years, because it might explain why individuals are constrained in their ability to respond to changes in their environment. Recent publications have shown that behavioural flexibility and personality might be linked; however, their interaction is not well understood and could be elucidated by studying a socially flexible species, such as the African striped mouse (Rhabdomys pumilio). Striped mice are an ideal species to address this topic because individuals of both sexes can follow different alternative reproductive tactics, which are reversible. Firstly, I investigated personality in striped mice by examining whether individuals showed consistency in their behavioural traits across time and context. Secondly, I addressed the interplay between personality, behavioural flexibility and social flexibility, by performing personality tests before and after individuals adopted a new reproductive tactic. Thirdly, I examined whether personality and behavioural syndromes measured under standardised laboratory conditions correlated with personality measures obtained from the striped mice in nature. Finally, I assessed whether the open field test and the startle test, two assays typically used to measure boldness, were correlated. The results of my research showed that personalities are well developed and highly stable over an individual’s entire lifespan even in this very flexible species. I found that some personality traits measured remained stable even after individuals adopted new tactics, and comparisons between individuals before and after tactic change indicated that personality traits were unable to successfully predict which tactic an individual would choose in the future. This is important as it shows that personality does not constrain behavioural flexibility. Further, I demonstrated that sexual selection can have a strong influence on personality, with males and females differing quite remarkably in their personality traits. By using a carefully validated methodology, my research additionally provides validation and support that personality measures obtained from standardised laboratory conditions are representative of individuals’ natural behaviours. Interestingly, I found that two separate latent variables (one for the field and one for the lab) underpinned all the behaviour measured indicating that there is a context-specific behavioural syndrome in this species. In sum, my study demonstrated that lifelong stable personality traits are well established in a socially flexible mammal. / XL2017

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ABSTRACT Environmentally-induced stereotypic behaviour (SB) results from the chronic impact of captivity on brain development and function and, consequently, on behaviour. My study sought to determine group- and individual-level predictors and correlates of SB in the striped mouse, Rhabdomys dilectus, and to identify the mechanisms underlying the stereotypic phenotype. This aim was addressed by collecting cross-sectional and longitudinal behavioural and physiological data from a combination of wild-caught (WC) and captive-born (CB) striped mice born and reared in different social and environmental conditions. First, I examined the group-level effects of rearing conditions. Results confirmed the genetic contribution to SB performance in striped mice, and furthermore indicated that (1) striped mice weaned at or later than their natural weaning age are less likely to develop SB than striped mice weaned prematurely; (2) striped mice reared biparentally showed significantly less SB as adults than striped mice reared by their mothers alone; (3) striped mice raised from weaning in enriched conditions were four times less likely than standard-housed individuals to develop SB, an effect which endured after enriched-housed striped mice were transferred to standard housing; and (4) birth origin predicts the emergence of SB in striped mice, with those WC individuals trapped as adults being relatively protected from the development of SB compared with both WC individuals trapped as juveniles and CB striped mice. I also showed that (1) WC striped mice were more fearful and less active than CB animals, but that these traits did not covary with SB, and (2) WC striped mice were less perseverative and behaviourally more flexible than CB animals, traits that did covary with SB. Second, I characterized the developmental trajectory of SB in a large group of CB, standard-housed striped mice, and then investigated potential individual-level predictors, mediators, and correlates of SB in these animals. Measures of perseveration, activity, and anxiety/fearfulness assessed in juveniles before the development of SB did not predict which animals later developed SB, but stereotypic adults were more active and more perseverative than nonstereotypic individuals. Whilst preweaning developmental maturity did not predict which striped mice later developed SB, striped mice showing accelerated development in the preweaning period were likely to show SB at an earlier age, at a higher frequency, and potentially with reduced variability, effects which persisted into adulthood. In conclusion, my study shows that more naturalistic rearing environments reduce the incidence of SB, an effect mediated by genetic factors and possibly also by experience-dependent alterations in forebrain function. However, further work is necessary to explore whether the association between forebrain function and SB expression in striped mice is causal because, whilst environments which decrease perseverative tendencies also reduce SB, I found no evidence that such tendencies predict which striped mice later develop SB.

Subclinical infections with the nematode Heligmosomoides polygyrus affect the behaviour and spatial learning of CD-1 mice in a Morris water maze. In early trials testing their ability to find and land on a hidden, submerged platform, uninfected mice displayed normal stress-related behaviours, such as avoiding the central areas of the circular maze and overswimming the platform. Infected mice manifested few such behaviours. Although both acquired the task, there were substantial differences between infected and uninfected mice in their patterns of task acquisition and execution. Although infected mice eventually reached comparable levels of competency, higher cognitive behaviours which suggest familiarity with the location of the platform, such as straight-line swimming, appeared earlier among uninfected mice. Other orientation behaviours, such as paddling and floating, occurred at higher levels among uninfected mice. These behavioural differences are discussed in terms of their adaptive significance to the survival of the host and the transmission of the parasite.

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Identifying the sensory systems animals employ to communicate chemically and the function of the chemical signals facilitates further understanding of chemical communication. Increased knowledge of how animals use the olfactory and vomeronasal systems in order to interpret the meaning of body odors will aid in developing a more detailed organization of chemosensory pathways. The message that each body odor contains can change from species to species. The purpose of this thesis was to study three previously untested body odors in house mice (M musculus) for their role in gender recognition of conspecifics. These odors are the anogenital (feces, urine, and preputial gland secretions), the Harderian gland (Harderian gland sebaceous secretion; gland located at inner comer of eye), and mouth/nose (saliva, mucus, and food). The amount of time in seconds and the number of sniffs were measured in an habituation paradigm which involved four trials per odor. The means of the amount of time spent sniffing and the number of sniffs per odor showed that the mice sniffed the novel odor the most, the non-novel an intermediate amount, and the control the least amount. The mice recognized the novel as foreign and the non-novel as familiar and the mice could not determine the gender of the odor-donor from any of the three odors.

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