Post-copulatory sexual selection (including sexual conflict) is a potent evolutionary force that can drive rapid divergence in reproductive traits. The Pitnick Lab is generally interested in the variety of ways in which members of the same sex compete for fertilizations and in which males and females cooperate with and/or attempt to manipulate one another in order to maximize their own fitness. We investigate the genetics and adaptive significance of variation in female reproductive tract design and of sperm production and use strategies in insects (presently fruit flies, yellow dung flies, diving beetles and flour beetles).  Primary conceptual interests include: (1) sperm-female coevolution, (2) the consequences of divergence in interacting sperm and female reproductive tract traits for reproductive isolation and speciation and (3) the interaction between sexual selection, ecology and life history evolution.  To address these topics, we explore trait variation within populations, among geographic populations and across species using behavioral, morphological, experimental evolution, quantitative genetic, phylogenetic and molecular approaches.