Dissertation Research: Genetics and the Evolution of Androdioecy in Datisca

雄蕊异株是一种繁殖群体由单独的雄性和雌雄同体个体组成，而雌雄异株群体则由雄性个体和雌性个体组成的繁殖系统。理论和系统发育表明，雄蕊异雄症起源于大戟属的雄蕊异雄症。此外，花形态表明雌雄同体是改良的雌性，而雄性有一个祖先的形式。本研究的总体目标是了解雄蕊异株从雄蕊异株的进化过程。杂交和分子标记将用于研究雄性雌雄异株植物datatisca glomerata及其雌雄异株姊妹种D. cannabina性别决定的遗传基础。此外，将在雌雄异株大麻大麻的自然种群中寻找性别比例扭曲者，以测试女性偏向的性别比例是否参与了雄性雄性进化的可能性。育种系统进化是植物中最容易控制和研究最多的进化过程之一。因此，它为整个进化提供了一个极好的模型。此外，由于大多数育种系统理论都是为其他育种系统发展起来的，因此雄雄性交配为控制育种系统进化的规则提供了一个独立的测试。这些研究将有助于解释通过自然选择使雄性不育在达蒂斯卡进化的遗传过程。更广泛地说，它们将阐明遗传学在育种系统进化和整体适应性进化中的作用。

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.