9507388 Zera Life history traits, such as the age at which reproduction begins, total egg production and duration of juvenile development differ dramatically among species. Understanding how these differences evolve is an important part in understanding modern patterns of biological diversity, yet we know very little about the mechanisms that are responsible for variation in life histories. This study will identify differences in endocrine mechanisms that underlie the first stages of life history evolution. It will determine how genetically based variation in key developmental and reproductive hormones cause populations to differ il life history traits, using crickets as a model system. The research will show whether differences in age of onset of reproduction result from differences in timing and concentration of juvenile hormone levels, or whether they result from genetically based differences in ovarian hormone receptors. The results will reveal the role of genetic differences in juvenile hormone or molting hormone systems in producing correlation between the duration of juvenile development and the onset of adult reproduction. The research is a synthesis of evolutionary genetics, insect endocrinology, and life history evolution. It will identify for the first time the specific mechanisms that underlie genetic differences in life history traits and correlations between those traits. In the long term, it may lead to new approaches to managing insect populations.
