Dissertation Research: A Molecular Examination of Homoploid Hybrid Speciation in Penstemon

杂交在新物种形成中的作用，特别是在二倍体水平上的作用，是植物进化的中心问题。俄克拉何马大学研究生安德里亚·沃尔夫（Andrea Wolfe）在指导教师韦恩·埃里森（Wayne Elisens）的指导下，提出在一个由四种多年生草本植物组成的盆草属植物复合体中，使用分子和遗传标记来测试关于同倍体杂交物种形成的各种假设。在每个物种范围内取样的单个植物将被调查同工酶（蛋白质）变异以及叶绿体DNA和核糖体DNA的突变差异。由于这些数据提供的遗传标记可以最大限度地减少性状中间性和显性性的问题，因此它们特别适用于检验关于杂交和渐渗的假设，以及来自稳定杂交重组的新物种的起源。这项研究提供了一个独特的机会，可以在一组密切相关的植物中测试两个杂交物种形成的例子。因为一种所谓的亲本物种——蜈蚣草（Penstemon centranthifolius），有许多可诊断的分子和遗传标记，将其与这个杂交复杂的其他成员区分开来，这组物种也提供了一个很好的系统来测试渐渗杂交模型，即基因从一个物种“泄漏”到另一个物种。

The role of hybridization in the formation of new species, particularly at the diploid level, is a central problem of plant evolution. Graduate student Andrea Wolfe, under the direction of faculty advisor Wayne Elisens at University of Oklahoma, proposes to test various hypotheses of homoploid hybrid speciation in a complex of four species of herbaceous perennials in the genus Penstemon, using molecular and genetic markers. Individual plants sampled throughout the range of each species will be surveyed for isozyme (protein) variation and for mutational differences in chloroplast DNA and in nuclear ribosomal DNA. Because these data provide genetic markers which minimize problems of character intermediacy and dominance, they are especially appropriate for testing hypotheses about hybridization and introgression, and the origin of new species from stabilized hybrid recombinants. The study represents a unique opportunity to test two examples of hybrid speciation in a group of closely related plants. Because one purported parental species, Penstemon centranthifolius, has numerous diagnostic molecular and genetic markers which distinguish it from other members of this hybrid complex, the group of species also offers an excellent system to test models of introgressive hybridization, the "leakage" of genes from one species into another.