Dissertation Research: Genetics and the Evolution of Androdioecy in Datisca

点击翻译按钮获取中文摘要

9902345Rieseberg Androdioecy is a breeding system in which breeding populations consist of separate male and hermaphrodite individuals, while dioecious populations contain male individuals and female individuals. Theory and phylogenetics suggest that androdioecy is derived from dioecy in Datisca. Furthermore, floral morphology suggests that hermaphrodites are modified females, while males have an ancestral form. The overall goal of this research is to understand the evolution of androdioecy from dioecy. Crosses and molecular markers will be used to investigate the genetic basis of sex determination in the androdioecious plant, Datisca glomerata and its dioecious sister-species, D. cannabina. Furthermore, a search for sex ratio distorters will be made in natural populations of dioecious D. cannabina to test the possibility that female-biased sex ratios were involved in the evolution of androdioecy.Breeding-system evolution is one of the most tractable and best-studied evolutionary processes in plants. Thus it provides an excellent model for evolution as a whole. Furthermore, because most breeding system theory was developed for other breeding systems, androdioecy provides an independent test of the rules thought to control breeding system evolution. These studies will help explain the genetic processes allowing androdioecy to evolve through natural selection in Datisca. More broadly, they will illuminate the role of genetics in breeding-system evolution and in adaptive evolution as a whole.