A fundamental question in biology is "How do new species arises?" This project will investigate the genetic basis of reproductive isolation in two species in the parasitic wasp genus Nasonia. Nasonia is a genetically tractable system with two important features, (a) symbiotic bacteria (Wolbachia) cause partial reproductive incompatibility between the species and (b) genetic incompatibilities also occur between nuclear and cytoplasmic components, some of which show simple inheritance patterns. The role of bacterial symbionts in causing reproductive incompatibility is one of interest because bacteria could represent a mechanism for rapid speciation in insects. This research is designed to assess the potential role of bacteria in promoting and/or maintaining reproductive isolation between the species. The distribution and degree of incompatibility within and between species will be quantified. Experiments will determine the probability of interspecies hybridization in the presence or absence of the bacteria. Using molecular markers, Dr. Werren will also determine whether few or many genes are involved in the genetic and cytoplasmic incompatibility between the two species. Results of these studies will help reveal the genetic mechanisms by which species diverge from each other and whether novel interactions, such as bacterial-insect associations, could play a role in speciation. Findings could have practical implications to conservation biology and preservation of biological diversity.***