Mate choosiness in young male fruit flies

Mate choice by males has been documented in many taxa including fruit flies (Drosophila spp.). It is still unclear, however, whether male mate choice varies much with age and one cannot readily predict the direction of change in male choosiness with age. We compared mate choice in young (1 day old) and mature (4 days old) male fruit flies (Drosophila melanogaster). Young males spent much less time courting heterospecific females than did mature males, but both male categories spent similar time courting conspecific females. We obtained similar results indicating higher selectivity of young than mature males in descendants of wild-caught flies, when males had an opportunity to learn to avoid heterospecific females and when males had a choice between courting conspecific and heterospecific females. The common methodology in the discipline has been to let virgin flies age for at least a few days prior to their use in experiments. Our experiments, which employed protocols sensitive to male age and experience, suggest that male fruit flies may be more choosy than previously thought and hence can contribute much more to sexual selection and incipient speciation than previously appreciated.