Postcopulatory 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 mainly investigate the evolution of sperm production and use strategies in Drosophila, as such traits exhibit rapid evolutionary divergence. We combine experimental evolution experiments in the laboratory, which reveal microevolutionary processes driving sperm length evolution, with comparative/phylogenetic studies discern the macroevolutionary pattern of sperm length and of other reproductive and life history traits over the past 60 million years.