Organisms are enormously genetically diverse. Even traits under strong natural selection, such as fertility, longevity, and reproductive behavior can vary greatly among individuals within a single population, and much of this variation can be heritable. We strive to understand why so much genetic variation persists for traits under strong selection and also to understand the consequences of this diversity for individuals, species, and communities. Members of the lab are studying the genetic, genomic, and evolutionary determinants of life span; the ecological genetics of sexual selection and mate choice; and genetic and social modifiers of growth,  behavior, and fitness. We use different experimental organisms, including fruit flies and several species of poeciliid fish, and a diversity of techniques, including quantitative genetics, evolutionary and behavioral genomics and field studies.