Symbioses between animals and microbes have evolved many times, and have been a major influence on macroevolutionary patterns of diversification as well as short-term evolution within host populations. My lab group works on symbioses between insects and bacteria, using evolutionary, functional and genomic approaches. I've been especially interested in how the population genetics of the symbionts affects mutation accumulation and ultimately their contributions to hosts. Using genomics and experiments with insects in the lab, we have found that symbionts can protect against parasites, supplement nutrition, and affect thermal tolerances. In the past, I have worked primarily with sap-feeding insects such as aphids and leafhoppers. During the past few years, we began work with gut microbiota in social bees, including honey bees and bumble bees. These offer the opportunity to culture the bacteria in the lab and to perform more sophisticated experiments to identify how hosts are impacted by particular bacterial species and particular bacterial genes.