Sexual selection for genetic quality: disentangling the roles of male and female behaviour

According to the good genes model of sexual selection, females choose males of good heritable genetic quality to obtain offspring with high fitness. However, better mating success of high-quality males can also be brought about by direct interference competition between males, or simply through elevated activity of high-quality males. We examined the roles of different processes leading to sexual selection for genetic quality in Drosophila montana. We manipulated genetic quality of male flies by inducing mutations with ionizing radiation. We then recorded the effects of inherited heterozygous mutations on several aspects of mating behaviour of males and females in two experiments. We found that mutations reduced the probability of courtship and extended the latency to courtship of the males, suggesting male activity plays a role in selection for genetic quality. However, the effects of mutations on mating success and mating behaviour of the flies were in general weak. No evidence for female mate choice or interference competition between males acting against heritable mutations was found.