Sex determination mechanisms vary wildly from phylum to phylum, even as evidence for their deep homology accumulates. This project uses the nematode genus Caenorhabditis to study how sex determination evolves over short time scales. It offers a well-characterized reference species (C. elegans), variation in sexual mode (androdioecy vs. gonochorism), and the first pair of closely related animal genome sequences. The project will develop C. briggsae as a true genetic system, which will enable precise comparisons with C. elegans. Two complementary approaches for identifying C. briggsae sex determination mutations are used: classical forward genetic screens based on phenotype and reverse genetic screens for deletion mutations via a PCR-based method. Together these approaches will help clarify how mating systems evolve, and whether the details of germline development are the same or different in two convergent hermaphroditic species. In addition, the project will contribute to the development of C. briggsae as a mature developmental genetic system. Undergraduate and graduate student participation is central to the project, ensuring that the training and mentoring of young scientists is a major component.
