Ontogenetic colour change in females as a function of antiharassment strategy

Abstract

Mate choice by females is an important component of sexual selection in many species. Theoretically, female sexual traits may be influenced by selection acting on the females via male mate choice, while the evolutionary consequences of male mate preferences are largely unknown, especially in the context of sexual conflict. We tested whether male mate choice affects the evolution of female colour in the damselfly Ischnura senegalensis in which females exhibit dimorphism consisting of a gynomorph that experiences ontogenetic colour change and an andromorph that does not. We first quantitatively confirmed that only gynomorphs change their body colour in relation to sexual maturation. In field experiments, males were unwilling to mate with sexually immature gynomorphs, although they attempted to mate with immature andromorphs. This is because males changed their mating preference for female colour depending on previous copulation experiences with sexually mature females. As a result, immature andromorphs received more male harassment than sexually immature gynomorphs, and then showed decreased food intake. Immature-specific colour functioned to avoid costly male harassment during female prereproductive stages, suggesting that ontogenetic colour changes in females have evolved as an antiharassment strategy of females via male mate choice. ► Female damselfly experienced ontogenetic colour change. ► Females with immature-specific colour efficiently avoided male harassment. ► Avoiding harassment increased food intake in females. ► Male choice may lead to the evolution of antiharassment strategy in females.