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

以前对虎耳草科开花植物的研究使用了来自形态、化学、染色体和杂交实验的证据。这些早期的调查有助于澄清传统上被认为是麻烦的类群中的属之间的分类关系。但鉴于其他植物组在形态和植物化学特征上平行和趋同进化的证据，这些虎耳草的系统发育亲缘关系仍然存在问题。华盛顿州立大学的道格拉斯·索尔蒂斯博士将应用强大的新方法，对叶绿体DNA进行突变分析，并对核糖体DNA进行较小程度的突变分析，以研究这一群体的进化变化。索尔蒂斯博士的分子系统分析的目标是：1.建立所研究的虎耳草科9个属的系统发育框架；2.研究单一种或单一模式属在这些较大的特殊属中的位置；3.将这种DNA分析的结果与其他分类证据的数据进行比较，如类黄酮化学、染色体和花形态。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.