The role of male–female interactions in the divergence of postmating–prezygotic reproductive traits has recently focused on sexual conflict as the selective force. While an association between mating costs and benefits suggests that antagonistic interactions may be important, a mosaic of processes may actually mediate the evolutionary dynamics of postmating–prezygotic interactions. Our study examines the ecological relevance of mating effects on females. We test this critical but often overlooked assumption in desert Drosophila, where the species' ecology provides a framework for evaluating the evolutionary implications of such mating consequences. We show that mating has a profound impact on an ecologically critical character—desiccation resistance. To explore what selective factors might underlie the observed population differences in mating effects, we test whether trends in the data match predictions based on the species' ecology. While these preliminary data are consistent with the expectation that the mating benefits are positively correlated with environmental conditions, further examination reveals an additional unanticipated association with the reproductive environment. This unexpected association challenges existing assumptions regarding the forces driving divergence of traits involved in mating.