Does female post-copulatory preference depend on pre-copulatory choice and post-mating environment?

Abstract

Sexual selection operates across pre- and post-copulatory episodes, driven by intra-sexual competition and inter-sexual choice for mates or gametes. In females, sexual selection often manifests as choosiness, however pre- and post-copulatory preferences can be in opposing directions. While relationships between male pre- and post-copulatory traits are well-studied, these relationships are less understood in females. Additionally, female post-copulatory environments can potentially influence post-copulatory choosiness, but this has been little investigated. Using Drosophila melanogaster, we explored whether mating latency, a proxy for inter-sexual pre-copulatory choosiness, correlates with female ejaculate ejection behaviour, a proxy for post-copulatory choosiness. We further tested whether the presence of a male in the females post-copulatory environment influences her ejection behaviour. We found no significant effect of male presence. However, males with longer mating latencies experience a smaller proportion of their sperm ejected, suggesting that males preferred as mates may produce sperm less favoured for fertilization. This finding might possible trade-offs between male investment in courtship and ejaculates. Our study highlights that female-mediated sexual selection at pre- and post-copulatory stages can shape sexual traits in complex ways. This has implications for sexual conflict, possibly providing an explanation for the maintenance of variation in sexually selected traits.