Dr. Fisher’s lab investigates the evolution of sexually selected traits, and specifically how cooperation, competition and conflict influence the selective regime. The duel nature of sperm cells, as both an extension of the diploid male that produced the gametes and as a unique haploid individual, generates an exceptional research model to study the social interactions within and between levels of biological organization (from sperm to males to populations). Work in the lab on Peromyscus rodents takes advantage of the extreme divergence in mating strategy within the genus and the wide range of natural phenotypic diversity that results.

One current research focus is to understand the molecular and physical mechanisms underlying a unique cooperative behavior observed in sperm of some Peromyscus species. These temporary aggregates enable the cells to migrate to the fertilization site with greater velocity compared to individual sperm; even more remarkably, in a species with intense sperm competition (P. maniculatus), sperm are able to recognize the most closely related cells and selectively group with them. This research is necessarily integrative and spans the fields of reproductive biology, evolutionary genetics and genomics, behavioral ecology and applied mathematics. Another research focus is understanding how the social environment influences the evolution of reproductive traits and behaviors. We ask how positive experiences, such as parental care, and negative experiences, such as social stress and competition, associate with differences in reproduction across the Peromyscus genus and within populations.