Post-copulatory sexual selection in females

Abstract

In lab adapted population males and females co evolve as a result of artificial selection pressure. While most of the studies on sexual selection focus on male reproductive traits, female traits can also co evolve and can play a role in overall reproductive fitness of population. In this study we investigate the female reproductive morphology in lab adapted populations of Drosophila melanogaster selected for differential levels of sexual selection by altering adult sex ratio. Previous studies in this population show that males from male biased (M) regime have a fitness advantage in terms of sperm competition over males from female biased (F) regime. Recent studies have shown that females do play a role in the outcome of sperm competition. We measured seminal receptacle length, which is shown to co evolve sperm length, and ovariole number, which is proportion to the total number of eggs produced by the female. Difference in morphology of these female reproductive traits would provide an insight into the role of female in outcome of post copulatory sexual selection. We found that M females have longer seminal receptacle than F females. We did not find any significant difference in ovariole number across selection regimes. Our results show that female reproductive trait also evolve in response to selection and would play a role in post copulatory sexual selection.