Cassandra Extavour wants to understand the functions and evolutionary origins of the genes, cells, and mechanisms that permit animals to reproduce and evolve. Extavour and her team are studying the fundamentals of germline evolution using a multidisciplinary, multi-level phylogenetic approach spanning nucleotides to networks to natural selection. Working in Drosophila and non-traditional model organisms, the team has revealed novel mechanisms and general principles of both embryonic germline/soma specification and gonad morphogenesis. This research has implications for understanding infertility and other pathologies of human reproduction.