DISSERTATION RESEARCH: Pollinator-mediated Interspecific Competition in Ipomoea

在许多植物物种中，自交物种都是从异交祖先反复进化而来的。然而，尽管植物交配系统进化的研究有很长的历史，但在对发生这种进化转变的生态背景的理解上存在重大差距。有几个假说将自体受精的进化与环境条件联系起来。一种这样的假说表明，当两个物种共存并竞争共享传粉者时，自花受精可能是有利的，作为一种减少对这种传粉者的依赖的手段，或者作为一种隔离机制来阻止它们之间的基因流动。这项拟议工作的目的是在两个牵牛花物种Ipomoea hederacea和I.Purpurea中检验这一假说。从达尔文时代到现在，自体受精和异体受精的重要性一直吸引着进化生物学家的兴趣。拟议的研究将是朝着更好地理解这两种生殖模式之间的过渡迈出的一步。白花蛇舌草和紫花蛇舌草之间的竞争相互作用将被作为一个模型来研究自花授粉作为生殖隔离机制可能发挥的作用，并解决关于授粉竞争可能有利于自花授粉的具体条件的更多机械性问题。

Self-fertilizing species have evolved repeatedly from outcrossing ancestors in a number of plant species. Despite the long history of work on plant mating system evolution, however, there are major gaps in the understanding of the ecological context in which this evolutionary transition occurs. Several hypotheses link the evolution of self-fertilization to environmental conditions. One such hypothesis suggests that self-fertilization can be advantageous when two species co-occur and compete for shared pollinators, as a means of reducing reliance on such pollinators or as an isolating mechanism to prevent gene flow between them. The purpose of the proposed work is to examine this hypothesis in the two morning glory species Ipomoea hederacea and I. purpurea. The significance of self- and cross-fertilization has interested evolutionary biologists from Darwin's time to the present. The proposed research will be a step towards a greater understanding of the transition between these two reproductive modes. The competitive interaction between I. hederacea and I. purpurea will be used as a model to examine the role self-fertilization may play as a reproductive isolating mechanism, and to address more mechanistic questions about the specific conditions under which competition for pollination is likely to favor self-fertilization.