Dissertation Research: Ecological Causes of the Evolution of Self-Pollination in Clarkia xantiana: The Role of Geographic Variation in Biotic Interactions

这项拟议的工作测试了关于克氏木兰(Clarkia Xantiana)自花授粉进化原因的假说。克氏木属是一种本土一年生植物，由异交和自花授粉的亚种组成。以前的工作表明，这两个亚种在地理范围、植物群落关联度和种群规模上都不同。这个项目考察了植物种群大小和植物群落相互作用在决定授粉蜜蜂的丰度以及异交和自花授粉交配系统是否有利的过程中所起的作用。这项拟议的工作研究了(1)蜜蜂授粉专家的分布和丰度与苍蝇交配系统和种群属性的关系；(2)影响繁殖产量的因素是否受授粉者丰度的限制；(3)种群大小和植物群落对不同交配系统的苍蝇个体相对成功的影响。我们将结合田间观察、田间实验和分子遗传分析来解决这些问题。自花授粉的进化是开花植物进化史上最常见的事件之一。虽然自花授粉的生物学后果(例如近亲交配)是众所周知的，但很少有人考虑这种进化转变的生态原因。该项目还将提供有关本地蜜蜂群落和植物群落在植物种群生存能力方面的重要性的新信息。

The proposed work tests hypotheses on the causes of the evolution of self-pollination in Clarkia xantiana, a native annual plant composed of an outcrossing and a self-pollinating subspecies. Previous work shows that the two subspecies differ in geographic range, plant community associations, and population size. This project examines the role of plant population size and plant community interactions in determining the abundance of pollinating bees and whether an outcrossing versus self-pollinating mating system is advantageous. The proposed work investigates (1) the distribution and abundance of specialist bee pollinators with respect to the mating system and population attributes of C. xantiana, (2) the factors affecting whether reproductive output is limited by the abundance of pollinators, and (3) the effects of population size and the plant community on the relative success of C. xantiana individuals that vary in mating system. A combination of field observations, field experiments, and molecular genetic analyses will be employed to address these problems.The evolution of self-pollination is among the most common events in the evolutionary history of flowering plants. While the biological consequences of self-pollination (e.g. inbreeding) are well known, the ecological causes of this evolutionary transition have rarely been considered. This project will also provide new information on the importance of native bee communities and plant communities in the viability of plant populations.