Dissertation Research: Causes and Consequences of Intrapopulation Variation in Lupinus Nanus (Leguminosae)

开花植物在交配制度上表现出很大的差异。目前用于描述植物交配系统的主要范式之一是混合交配模型。完美的开花植物被认为是通过某种自交和异交授粉的组合来繁殖的。异交事件产生的种子比例或异交率可在0和1之间变化。虽然实证研究已经确定了代表所有潜在异交率的自然植物种群，但理论预测表明，自然选择应该作用于中间异交率，以产生极端的完全异交或完全自交。目前还没有自然选择的力量作用于中间异交率的经验证据来检验这些理论预测。提出的研究将解决中间异交率的进化动力学在一个自然种群的加利福尼亚羽扇豆，羽扇豆。在整个物种范围内对种群的异交率进行了估计，并表明种群之间存在很大差异，大多数种群的异交率处于中等水平。种群间的形态差异被认为是异交率变化的重要决定因素。在同一种群中，不同年份和种群内个体的异交率也发生了变化。拟议的研究将侧重于种群内交配制度的变化。将测量单株植物的形态、物候和生态特征。将从这些植物中收集自然授粉的种子，并利用淀粉凝胶电泳收集的遗传信息确定个体的异交率。此外，将进行人工自交和异交授粉，并将种子用于评估自交和异交后代的相对成功率。有了这些信息，就可以确定选择对异交率的影响。本研究除了为检验交配系统进化的理论预期提供经验证据外，还将为植物育种家提供具有普遍价值的信息。

Flowering plant species exhibit a great deal of variation in their mating systems. One of the dominant paradigms currently used to describe plant mating systems is the mixed-mating model. Perfect flowered plants are understood to reproduce through some combination of self and outcross pollinations. The proportion of seeds produced by outcrossing events, or outcrossing rate, can vary between 0 and 1. While empirical investigations have identified natural plant populations representing the full range of potential outcrossing rates, theoretical predictions suggest that natural selection should act on intermediate outcrossing rates to produce either extreme of complete outcrossing or complete selfing. There is currently no empirical evidence of the forces of natural selection acting upon intermediate outcrossing rates with which to test these theoretical predictions. The proposed research will address the evolutionary dynamics of intermediate outcrossing rates in a natural population of the annual California lupine, Lupinus nanus. Estimates of outcrossing rates have been made for populations throughout the species' range, and demonstrate a great deal of variation between populations, with most of the populations outcrossing at intermediate rates. Morphological variation between populations has been suggested as an important determinant of the variable outcrossing rates. Outcrossing rate variation had also been reported for the same population between years, and for individuals within a population. The proposed research will focus on mating system variation within a population. Individual plants will be measured for morphological, phenological and ecological characters. Naturally pollinated seed will be collected from these plants, and the outcrossing rate for individuals will be determined using genetic information gathered from the use of starch-gel electrophorsis. In addition, artificial self and outcross pollinations will be performed and the seed will be used to assess the relative success of selfed and outcrossed offspring. With this information, the effect of selection on the outcrossing rate can be determined. In addition to providing empirical evidence for testing the theoretical expectations concerning mating system evolution, this study will also provide information of general value of plant breeders.