Male reproductive performance: Influence of age, sex and diet on fecundity and offspring quality

Abstract

Male reproduction bears an energetic cost, making reproductive performance dependent on resource availability and the previous utilisation of those resources. This thesis examines how male post-copulatory reproductive performance responds to different condition-determining factors through two experimental studies, using the neriid fly Telostylinus angusticollis. Offspring quantity, trans-generational paternal effects and male reproductive morphology were used as measures of reproductive performance, making this one of the few studies to include trans-generational effects when examining male reproductive plasticity. Chapter one aimed to determine any interactions of determinants of male condition at the larval and adult stage, as well as male mating history on reproductive performance. It is demonstrated that protein consumed by males at the adult stage interacts with male age to influence larval viability of the offspring. Moreover, it was found that female fecundity stimulation induced by the male shows complex condition-dependent responses to male environment and age. Chapter two aimed to determine if there was a cost to frequent mating on male reproductive performance. It was found that males that had mated frequently could achieve similar reproductive performance as that of virgin males. It was also found that larval viability is influenced by male accessory gland size and that male mating history influences accessory gland size, although no effect of mating history on larval viability was found. This thesis provides insight into how male reproductive performance responds to varying environments and determinants of male condition. It also demonstrates that male reproductive performance should not be limited to offspring quantity, but should include trans-generational paternal effects such as offspring viability and condition.