Sexual selection in a lekking Hawaiian Drosophila: the roles of male competition and female choice in male mating success

Abstract

The importance of sexual selection in Drosophila grimshawi, a lek-forming Hawaiian Drosophila, was analysed in the laboratory by studying details of male and female mating behaviour at spontaneouslyforming leks in large and in small observation chambers. Sexual selection was found to be intense, as is often hypothesized for Hawaiian Drosophila. However, little evidence was found for a significant role of active female choice in male mating success although females can reject attempted copulations. Male body size was significantly related to mating success, but mostly because large males spent more time sexually active at lek sites, which resulted in increased mating success, and not because large males physically dominated smaller ones. Variation in larval environmental quality significantly affected male size, and thus, environmental factors may have a large, but indirect, influence on male mating sucess.