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

提出的工作测试了对克拉克兰自花授粉进化原因的假设，克拉克兰是一种由异交和自花授粉亚种组成的本地一年生植物。先前的研究表明，这两个亚种在地理范围、植物群落关联和种群规模上存在差异。本项目研究了植物种群大小和植物群落相互作用在决定授粉蜜蜂丰度方面的作用，以及异交与自花授粉的交配系统是否有利。本研究主要研究了黄天麻的分布、传粉媒介丰度与交配系统、种群属性之间的关系，探讨了黄天麻的生殖输出是否受到传粉媒介丰度的限制，以及黄天麻种群大小和植物群落对不同交配系统下黄天麻个体相对成功的影响。将采用现场观察、现场实验和分子遗传分析相结合的方法来解决这些问题。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（例如近亲繁殖）是众所周知的，但这种进化转变的生态原因很少被考虑。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中的重要性的新信息。

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.