The Evolution of Dioecy and Sexual Dimorphism: An Integrative Approach Using a Gynodioecious Strawberry

9707247种阿什曼分离的雄性和雌性开花植物(雌雄异株)是由雌雄同体的祖先在众多谱系中独立进化而来的，这使得进化生物学家得出结论，这种转变是生物学中的一个中心问题。然而，对于这种转变是如何发生的，我们并没有一个完整的图景。一项密集建模的理论预测，雌雄同体的种群是雌雄异株的中间步骤。雌性的存在预计会导致雌雄同体的选择变得更具男性性，如果存在某些遗传条件，那么雌雄异株就可以进化。这项研究将通过描述模式系统--野生草莓(Fragaria Virginiana)的遗传结构，探讨雌雄异株进化的潜力，该系统表现出一个过渡的繁殖系统，以及选择性环境的一个基本方面(雌性频率)的种群间变异。通过描述四个野生草莓种群(雌性频率连续体两端各两个)生殖性状(花粉产生、座果和花瓣)之间的遗传关系，这项研究不仅将揭示对选择的反应潜力，而且还将评估生殖进化理论模型的假设和稳健性。此外，种群间的比较将产生关于遗传参数的不变性以及这种不变性对进化变化的后果的信息。这项研究将提供有关生殖系统进化的信息，这些信息与进化生物学基本相关，因为所有生物体都面临与这里研究的生殖分配决定相似的分配决定。植物生殖系统与许多其他系统一样，器官在功能和结构上是同源的，因此必然具有共同的发育和遗传基础。了解遗传结构对个体表型和性别二型性进化的制约是进化生物学的一个重要方面。此外，种群之间的比较将提供关于遗传结构不稳定的信息，并将对检验应用于进化问题的数量遗传学的假设做出重大贡献。

9707247 Ashman Separate male and female flowering plants (dioecy) have evolved from hermaphrodite ancestors independently in numerous lineages, leading evolutionary biologists to conclude that such a transition is a central problem in biology. However, we do not have a complete picture of how this transition occurs. An intensively modeled theory predicts that populations with females and hermaphrodites are an intermediate step to dioecy. The presence of females is expected to result in selection on hermaphrodites to become more male in gender, and if certain genetic conditions exist then dioecy can evolve. This research will address the potential for dioecy to evolve by characterizing the genetic architecture of a model system, the wild strawberry (Fragaria virginiana), that exhibits a transitional breeding system and among-population variation in a fundamental aspect of the selective environment (the frequency of females). By characterizing the genetic relationships among reproductive traits (pollen production, fruit set, and petals) in four populations of wild strawberry (two from each end of the female frequency continuum), this research will not only reveal the potential for response to selection, but it will also evaluate the assumptions and the robustness of theoretical models of reproductive evolution. Furthermore, among-population comparisons will yield information on the constancy of genetic parameters and the consequences of such constancy for evolutionary change. This research will provide information on the evolution of reproductive systems, information that is fundamentally relevant to evolutionary biology because all organisms face allocation decisions similar to the reproductive allocation decisions studied here. Plant reproductive systems are like many other systems where organs are functionally and structurally homologous, and thus necessarily have a shared developmental and genetic basis. Gaining an understanding of the constraints imposed by genetic architectur e on the evolution of individual phenotype and sexual dimorphism is an essential aspect of evolutionary biology. Furthermore, comparisons among populations will provide information on the lability of genetic architecture and will make a significant contribution to testing the assumptions of quantitative genetics as applied to evolutionary questions.