Evolutionary behavioural ecology of an Australian lizard with alternative reproductive tactics

Evolution by natural and sexual selection requires an understanding of trait variability and heritability and the strength and form of selection on phenotypic traits. This thesis is an integrative overview of these important tenants of evolutionary biology using a model lizard system, Eiilampnis qiioyii. I begin by exploring the individual level of variability in spatial cognitive traits among males and test whether individuals are capable of complex spatial learning under semi-natural conditions. Contrary to previous research, I show that lizards are capable of quick and flexible spatial learning as would be predicted given its close link with fitness in the wild. In more controlled conditions, I test for sex differences in spatial learning and whether individual behavioural traits, linked to personality, affect spatial learning ability. As predicted, there were sex-differences in spatial learning, representing the first evidence of cognitive differences between the sexes in a reptile. In contrast to recent theory, I show that behavioural types were not linearly associated with cognitive performance in the spatial task and this may be a result of alternative mating tactics in E. quoyii. In the second part of my thesis I explore how selection acts on behavioural and performance traits using a large-scale breeding experiment under seminatural conditions. Using a genetic pedigree, I test two alternative hypotheses for the prevalence of polyandry in this system and assess the degree to which offspring performance traits are heritable. I show that polyandry may evolve through direct benefits females receive through multiple mating rather than genetics benefits, given that offspring from single and multiple paternity females did not differ in fitness and because the fitness traits showed weak heritability. Finally, I test how natural and sexual selection act on behavioural and performance traits. I show that selection acts on behavioural traits disruptively possibly promoting the evolution of ARTs in E. quoyii. Selection on performance also suggests that different ARTs adopt different mechanisms to acquire paternity and that behaviours may be integrated with whole-organism perfonnance traits. Patterns of selection on performance traits also provide a possible explanation for sex- differences in morphology and performance 1 observed in E. quoyii.