No Evidence of Sexually Antagonistic Coevolution in Drosophila Reproductive Tract Transcriptomes

Drosophila seminal fluid proteins (SFPs) are often cited as an example of interlocus sexual conflict, wherein the proteins increase male fitness while decreasing female fitness, spurring recurring female counter-adaptations and rapid molecular evolution. This model predicts that male-expressed genetic variation in the accessory gland, which produces seminal fluid, should generate counter-evolving genetic pathways in females, resulting in sexual coevolution. Using a trio of D. melanogaster populations exhibiting substantial SFP expression divergence due to recent selection, we test for coevolution in the female post-mating transcriptome in the lower reproductive tract and head. Contrasting predictions of sexual antagonism, female post-mating gene expression is indifferent to male population of origin. Instead, our results better support the alternative hypotheses that environmental variation is the source of selection on male SFP gene expression and that population differentiation in the female post-mating transcriptome is generated by female-expressed genotypic differentiation.