DISSERTATION RESEARCH: Pollinator-mediated Interspecific Competition in Ipomoea

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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.