Sexual Motivation and Mate Choice in the Female Smooth Newt, Triturus vulgaris

Abstract

This thesis describes a study of sexual motivation and mate choice in the female smooth newt, Triturus vulgaris. Chapter one introduces the species' natural and life histories and sexual behaviour. It also describes the different approaches (causal and functional) that have been employed and explains why a female perspective has been particularly emphasised. Chapter three reports the results of the preliminary study of female sexual motivation which provided the basis for further investigation. Chapter four discusses some of the results of the follow-up study. Female sexual responsiveness was monitored over a complete breeding season. The relationship between inseminations and egg-laying was investigated. This chapter essentially looked at female sexual responsiveness from a functional perspective. It was found to vary greatly, and was affected by egg-laying and time of season. Chapter five discusses female sexual responsiveness in the same study reported in Chapter four, but from a causal perspective. Female sexual behaviour was described in detail, behaviour patterns were defined and motivation scores were devised to examine variation over the season. Chapter six examines female mate choice. Aspects of male morphology, spermatophore pick-up and partner familiarity were investigated. Females were found to show discrimination for larger-crested males, but this discrimination varied and was related to sexual motivation. Chapter seven reports an investigation into how females perceive the stimuli presented to them by the male during his display. The relative importance of visual and olfactory stimuli was studied, as well as the effect of the combination of both sets of cues. Chapter eight re-examines the value to this area of research of using the different approaches and perspectives employed here and discusses the results of all the experiments performed.