REU: Phylogenetic Relationships and Evolution in the Heuchera Group (Saxifragaceae) Using DNA Restriction Fragment Analysis

以往对开花植物萨克斯科植物的研究主要利用形态学、化学、染色体和杂交实验的证据。这些早期的研究有助于澄清在传统上被认为是一个麻烦的群体中的属之间的分类关系。但鉴于其他植物类群在形态和植物化学特征上存在平行和趋同进化的证据，这些蕨类植物的系统发育亲缘性仍然存在问题。华盛顿州立大学（Washington State University）的道格拉斯·索尔蒂斯（Douglas Soltis）博士将运用对叶绿体DNA进行突变分析的强大新方法，以及在较小程度上对核糖体DNA进行突变分析的新方法，来研究这一群体的进化变化。Soltis博士分子系统分析的目标是：1 .为所研究的Saxifragaceae九属（包括大属Heuchera， Lithophragma和Mitella）构建一个系统发育框架；2. 检查单种或单型属在这些较大的种属中的位置；和3。将DNA分析结果与其他分类证据（如类黄酮化学、染色体和花形态）的数据进行比较。这样，就有可能评估形态、染色体和植物化学的进化变化模式。

Previous studies of plants in the flowering plant family Saxifragaceae have used evidence from morphology, chemistry, chromosomes, and hybridization experiments. These earlier investigations have helped to clarify taxonomic relationships among genera in what has traditionally been considered a troublesome group. But given the evidence of parallel and convergent evolution in morphological and phytochemical characters in other plant groups, the phylogenetic affinities of these saxifrages remain problematic. Dr. Douglas Soltis of Washington State University will apply the powerful new methods of mutational analysis of chloroplast DNA, and to a lesser extent, nuclear ribosomal DNA, to examine evolutionary change within this group. The goals of Dr. Soltis's molecular systematic analysis are to: l. construct a phylogenetic framework for the nine genera of Saxifragaceae under study, including the large genera Heuchera, Lithophragma, and Mitella; 2. examine the placement of single-species or monotypic genera among such larger, speciose genera; and 3. compare the results from this analysis of DNA with data from other lines of taxonomic evidence such as flavonoid chemistry, chromosomes, and floral morphology. In this way, it will be possible to assess patterns of evolutionary change in morphology, chromosomes, and phytochemistry.