Dissertation Research: Phylogeny and Speciation in Polygonella (Polygonaceae)

研究生保罗·刘易斯将在俄亥俄州立大学丹·克劳福德博士的指导下，研究美国东南部11种何首乌属植物的分类学和遗传变异性。在这个属中，有几个物种似乎在更新世冰川融化的温暖时期进化成了孤立的岛状种群。在这些时期，佛罗里达半岛被淹没，但代表该地区最高陆地的“岛屿”除外。例如，有两个物种仅限于沿着佛罗里达半岛中心延伸的威尔士湖山脊，其他物种可能已经从这个特有地区扩散出去。这项研究将通过使用电泳法测量酶的变异来检查物种内和物种之间的形态变异以及植物的遗传变异。酶电泳法检测到的基因特征可能会产生有用的数据，用于推断物种之间的进化关系，并估计这些植物的育种系统的各个方面，众所周知，这些植物的性别表达是不同的。因此，虎杖属提供了一个不同寻常的机会，可以调查与更新世岛屿形成有关的过去物种形成事件，这可能有助于揭示佛罗里达州许多特有动植物的起源。

Graduate student Paul Lewis, under the supervision of Dr. Dan Crawford of Ohio State University, will study the taxonomy and genetic variability of 11 species of the genus Polygonella of the southeastern United States. In this genus several species appear to have evolved as isolated island-like populations during the warm periods between Pleistocene ice ages when glaciers melted. The Florida Peninsula was submerged during these times with the exception of "islands" that represented the highest land masses in the area. Two species of Polygonella for example are restricted to the Lake Wales ridge running down the center of the Florida peninsula, and other species may have dispersed from this endemic area. The study will examine morphological variability within and among the species and also genetic variation of plants by measuring enzyme variation using electrophoresis. Gene-characters detected by enzyme electrophoresis are likely to yield data useful for inferring evolutionary relationships among the species and for estimating aspects of breeding systems in these plants, which are known to be variable in sex expression. Thus Polygonella provides an unusual opportunity to investigate past speciation events associated with Pleistocene island formation which may shed light on the origin of many of Florida's endemic plants and animals.