Sexual reproduction requires cooperation between males and females, but the evolutionary interests of the sexes often differ. We are studying this sexual conflict in Drosophila melanogaster using several different approaches. In order to test whether exposure to males truly comes at a cost to females, we are conducting manipulative experiments that vary female exposure to males and then examining the fitness consequences for females. We are also studying some of the traits that might mediate female costs, including male seminal fluid proteins, by manipulating expression of genes encoding these proteins.

Speciation occurs when populations evolve barriers to reproduction. Understanding how these barriers form is a longstanding challenge in evolutionary biology because recurrent migration is expected to erase any emerging differences between populations. One way in which speciation might be completed is through a process called reinforcement, where natural selection favors the avoidance of hybridization when hybrid offspring are less fit. We are examining whether relatively weak barriers to reproduction between populations are strengthened or decay when populations experience reinforcing selection over evolutionary time.

Each year, millions of people are infected with an arbovirus following a bite from a female Aedes mosquito. Release of sterile males has sometimes successfully suppressed vector populations by reducing female reproduction, but large numbers of males are required because “domesticated” males used in releases tend to be relatively poor sexual competitors. With an international team, we are evolving replicate populations of Aedes aegypti under varying intensities of sexual selection and measuring the effect of these environments on male competitiveness, colony productivity, and predicted population suppression efficiency. By harnessing sexual selection, we hope to identify the genomic basis of male sexual competitiveness and improve the performance of released males.

Oceanic island archipelagos—isolated regions comprised of many geographically clustered islands—provide powerful natural laboratories to better understand how the distribution of genetic variation in space and time is shaped by selection, gene flow, and genetic drift. In collaboration with the group of Maria de Lourdes Torres at USFQ in Ecuador, we are studying a number of flying insects on the Galapagos islands. We recently built the genome of the Galapagos carpenter bee, Xylocopa darwini, and we are using whole-genome sequencing to understand the timing and order of colonization of the islands as well as the forces responsible for genetic differences between island populations.