Dissertation Research: Phylogeny and Speciation in Polygonella (Polygonaceae)

点击翻译按钮获取中文摘要

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.