The evolutionary history of eukaryotes is tightly linked to endosymbiosis and sexual reproduction. Not only was the evolution of eukaryotic life facilitated by the acquisition and vertical inheritance of intracellular microbes, but intracellular symbionts, organelles, and pathogens continue to sculpt the evolutionary trajectories of eukaryotes broadly. In insects and other arthropods, there is an abundance of recently acquired endosymbionts that have evolved mechanisms for altering host sex and reproduction. Approximately half of all insects are infected with one such bacterium: Wolbachia. Despite how common Wolbachia is, we know relatively little about the mechanisms by which Wolbachia establishes infection in insects, alters their biology, and how this symbiosis and change in reproduction in turn affects insect evolution. We use a range of genomic, molecular, and computational approaches to investigate insect-Wolbachia interactions. Some of the questions we are currently interested in include: (1) the mechanisms of Wolbachia-mediated changes in insect biology, (2) how Wolbachia and other symbionts convert their host to asexual reproduction, and (3) the genomic and evolutionary consequences of symbiosis with Wolbachia and subsequent changes in reproduction. Below are some of the systems we use to understand symbiosis and sex.
Parasitoid Wasps and Asexual Reproduction
Many species of parasitoid wasps harbor Wolbachia strains that convert them to a form of asexual reproduction: thelytokous parthenogenesis. Sometimes, this switch to asexuality can be permanent: wasps rely upon Wolbachia for the continued production of females. We are interested in the mechanistic basis of parthenogenesis induction, and the evolutionary consequences of Wolbachia-mediated loss of sex. We use wasps in the genera Trichogramma and Leptopilina to study insect-parasitoid, parasitioid-Wolbachia, and insect-parasitoid-Wolbachia interactions.
Drosophila as a model for uncovering fundamental aspects of Wolbachia infection
Across the Drosophila genus, there are numerous strains of Wolbachia that affect their fly hosts in various ways. Some harbor Wolbachia strains that cause sperm-egg incompatibilities. Other Wolbachia can make their host recalcitrant to secondary infections with RNA viruses, and are being transferred to mosquitoes for use in vector control programs. Certain Drosophila species host multiple co-infecting Wolbachia. The diversity of host-Wolbachia interactions in this group coupled with genetic tools available for Drosophila melanogaster make this an excellent system study fundamental aspects of Wolbachia-host interactions, and a useful surrogate system for investigating protein function in some of our more difficult to work with symbiosis, such as the asexual parasitoid wasps.