Dissertation Research: Comparing Prezygotic Isolating Mechanisms in Unimodal and Bimodal Plant Hybrid Zones.

本研究评估了限制植物自然杂交的生态和遗传机制的相对重要性。在美国西部山区的几个地点，两种密切相关的Ipomopsis植物近距离生长。通过比较杂交常见的接触点和两种相同物种没有成功杂交而是形成形态双峰分布的接触点，可以研究不同分离机制对杂交率的重要性。用分子方法比较低频率和高频率杂交位点的基因渗入程度。将在每个地点检查鸟类和昆虫传粉者的行为，以测试由行为选择或传粉者传递花粉的能力引起的基因流的差异。实验授粉将测试来自其他物种的花粉竞争能力的差异。杂交率在不同的分类群之间差别很大。了解其中的原因将有助于理解物种差异和生物多样性是如何维持的基本问题。它还可以帮助预测与转基因作物或入侵植物杂交的影响。

This study assesses the relative importance of ecological and genetic mechanisms that restrict natural hybridization in plants. Two closely related species of Ipomopsis plants grow in close proximity in several sites in the mountains of the western U.S. By comparing contact sites where hybrids are common with a contact site where the same two species do not hybridize successfully and instead form a bimodal distribution of morphologies, it is possible to investigate the importance of different isolating mechanisms to the rate of hybridization. Sites with low versus high frequencies of hybrids will be compared with respect to the degree of introgression of genes using molecular methods. Behavior of bird and insect pollinators will be examined at each site to test for differences in gene flow induced by behavioral choices or ability of pollinators to transfer pollen. Experimental pollinations will test for differences in the competitive ability of pollen from another species.Hybridization rates vary tremendously across different taxonomic groups. Understanding the reasons why will contribute to an understanding of the fundamental problem of how species differences and biological diversity are maintained. It could also help in predicting impacts of hybridization with genetically engineered crops or with invasive plant species.