The research in Dr. Hofmann's laboratory seeks to understand the molecular and hormonal mechanisms that underlie social behavior and its evolution. African cichlid fishes are an ideal model system to address these questions because of their recent, repeated and rapid radiations that have resulted in hundreds of phenotypically diverse species. Our work uses a broad spectrum of approaches, ranging from ecological studies in the East African Great Lakes to gene expression profiling in the brain. We also employ hormonal perturbations, neuroanatomical techniques and advanced microscopy, and bioinformatics tools. Although we have been working on a variety of topics in several model systems, current projects focus on two main areas: 1) Identifying genes that are involved in implementing social dominance and sex roles in the Tanganyikan mouthbrooder Astatotilapia burtoni; and 2) a comparative analysis of the ecological and molecular basis and evolution of divergent social organization (monogamy vs. polygamy) in a group of closely related (monophyletic) species, the Ectodini cichlids from Lake Tanganyika. By carefully and systematically querying the brains of these fish, we can use expression profiling to identify the molecular building blocks of complex behavior.