Dissertation Research: Selective Forces in the Evolution of Gender Specialization in the Genus Lycium (Solanaceae)

Venable 9801391 在枸杞属（茄科），一种沙漠灌木属， 使用系统发育框架。 枸杞是不寻常的拥有这两个 雌雄同体和雌雄分离的物种， 不同性别的进化起源。 具体而言， 将通过调查以下因素来估计异交的选择： 自交亲和性、近交衰退和自然自交率。 还有， 女性是否通过重新分配来补偿男性功能的丧失 资源和这种补偿效应的重要性将被确定 利用从几个生殖组成部分收集的数据。 模型是 使我们能够评估这些组件的重要性 性别分工的演变。 这两个假设将是 通过首先推断系统发育关系（ 进化树）在属，使用形态和分子 数据，然后进行比较二态和单态姐妹 分类群 性别系统的进化是生物学中一个重要的普遍问题，几十年来一直吸引着进化生物学家。 本研究 该项目将阐明选择性力量对进化的作用， 性别专业化。 植物是一个很好的系统， 性别的进化，因为他们在性别上的巨大差异 系统及其在该领域的易用性。 虽然性别 专业化是一种相对罕见的情况（发生在10%的 被子植物物种），它在许多不相关的分类群之间的重复进化使 这是一个重要的进化问题。 比较数据经常被 用于研究植物性别的进化，但这些分析 通常是有缺陷的。 人们一再呼吁， 比较数据分析。 这里所采用的方法， 功能研究与健全的系统发育比较，是一个答案， 这一呼吁，并将提供一个重要的贡献， 植物性别特化的解释。

Venable 9801391 The selective forces responsible for the evolution of gender specialization are being investigated in Lycium (Solanaceae), a genus of desert shrubs, using a phylogenetic framework. Lycium is unusual in possessing both hermaphroditic and separate-sexed species and in having multiple evolutionary origins of separate sexes. Specifically, the importance of selection for outcrossing will be estimated through investigation of self-compatibility, inbreeding depression, and natural selfing rates. Also, whether females compensate for loss of male function by reallocating resources and the importance of this compensation effect will be determined using data collected for several reproductive components. A model is developed that enables us to evaluate the significance of these components to the evolution of gender specialization. These two hypotheses will be explicitly tested by first inferring phylogenetic relationships (the evolutionary tree) in the genus, using both morphological and molecular data, and then making comparisons between dimorphic and monomorphic sister taxa. The evolution of gender systems is an important general issue in biology that has intrigued evolutionary biologists for decades. This research project will elucidate the selective forces operating on the evolution of gender specialization. Plants make excellent systems in which to study the evolution of gender, both because of their tremendous variation in gender systems and their ease of study in the field. Although gender specialization is a relatively rare condition (occurring in 10% of angiosperm species), its repeated evolution among many unrelated taxa makes it an important evolutionary issue. Comparative data have frequently been used to study the evolution of gender in plants, but the analyses have usually been flawed. There have been repeated calls for a more careful analysis of comparative data. The approach taken here, of combining field studies of function with sound phylogenetic comparisons, is one answer to this call, and will provide an important contribution to the evolutionary interpretation of gender specialization in plants.