Male mate choice in the stick insect Clitarchus hookeri : sexual vs. parthenogenetic females : a thesis presented in partial fulfilment of the requirements for the degree of Master of Science in Zoology at Massey University, Manawatū, New Zealand

Learning about reproductive strategies in animals is an important step for understanding the evolution of species. New Zealand stick insect, Clitarchus hookeri include both sexual and parthenogenetic females, and parthenogenetic females occur in the distributional range where males are absent and have a limited capacity of sexual reproduction. Since C. hookeri exhibit a scramble competition mating system with distinctive sex roles where females and males co-occur, it is likely that parthenogenetic females do not exhibit traits that are related to the sex roles. Furthermore, due to limited capacity for parthenogenetic females to reproduce sexually, it is likely that C. hookeri males would benefit from discriminating between sexual and parthenogenetic females. The main purpose of this thesis was to explore the unique reproductive features of Clitarchus hookeri. Specifically, I identified morphological and chemical traits that are likely to be under distinctive sex roles in scramble competition; revealed whether morphological and chemical traits seen in sexual females are also seen in parthenogenetic females; and observed whether males can discriminate between sexual and parthenogenetic females for their pre- and post-copulatory choices. As a result, C. hookeri exhibited sexual differentiation in terms of morphology and chemical signalling that are advantageous to their roles in scramble competition. However, sexual and parthenogenetic females overlapped in their phenotypic traits, and males failed to discriminate between sexual vs. parthenogenetic females both in pre- and post-copulatory choices. These results suggest the possibility of the maintenance of sexual traits in parthenogenetic females; and therefore males have failed to discriminate between females with a different reproductive mode