Ecological Speciation and the Physiological Performance of Plant Hybrids in Ipomopsis

拟议的研究涉及新物种形成和维持的生态机制。 在植物中，一种机制涉及传粉者介导的自然选择：两种花专门针对不同的动物传粉者，杂交后代接受低授粉。 另一种可能性是环境介导的选择：栖息地之间的选择差异导致杂交种的遗传不相容性或杂交种对亲本环境的生理适应性差。环境介导的选择将通过测量Ipomopsis杂交种和亲本物种的生理性能和适合度来测试。首先，生理性状（包括光合作用，水分利用效率）将被测量为环境变量的函数。其次，将不同遗传背景的种子种植到不同的栖息地，并随后测试不同的营养和生理性状是否有利于在两个亲本栖息地。环境介导的选择的强度将与传粉媒介介导的选择进行比较。 DNA样本将被储存起来，用于将来对关键性状进行遗传作图。 这项工作将生理学方法融入进化过程的研究中。 这将有助于解释为什么植物杂交在适应性上各不相同，并有助于了解物种形成，这是进化中的一个基本问题。 这些结果对农业和保护具有潜在的好处。 它们可能有助于预测影响基因从转基因作物逃逸到野生亲缘植物的条件，以及入侵植物和本地植物之间的杂交。 这项研究为本科生、研究生和博士后学生提供培训。

The proposed research addresses ecological mechanisms by which new species are formed and maintained. In plants, one mechanism involves natural selection mediated by pollinators: two flower species specialize on different animal pollinators, and hybrids receive low pollination. Another possibility is environment-mediated selection: differences in selection between habitats produce genetic incompatibility in hybrids or poor physiological adaptation of hybrids to parental environments. Environment-mediated selection will be tested by measuring physiological performance and fitness of Ipomopsis hybrids and parental species. First, physiological traits (including photosynthesis, water-use efficiency) will be measured as functions of environmental variables. Second, seeds of varying genetic background will be planted into different habitats and followed to test whether divergent vegetative and physiological traits are favored in the two parental habitats. The strength of environment-mediated selection will be compared with pollinator-mediated selection. DNA samples will be stored for future genetic mapping of critical traits. This work integrates physiological methods into the study of evolutionary processes. It will help explain why plant hybrids vary in fitness and contribute to knowledge of speciation, a fundamental issue in evolution. The results have potential benefits to agriculture and conservation. They may help in predicting conditions influencing escape of genes from genetically modified crops into wild relatives, and hybridization between invasive and native plants. The research provides training for undergraduate, graduate, and postdoctoral students.