Incomplete concerted evolution in the non-hybrid diploid Clematis fremontii S. Watson (Ranunculaceae)

Clematis fremontii S. Wats. (Ranunculaceae) is a diploid perennial forb with strict habitat requirements that occurs in isolated populations in the cedar glades of Missouri and the mixed-grass prairies of Kansas and Nebraska. Based on geographical isolation and morphological differences, this species was formerly subdivided into two varieties, the autonymic prairie variety and the glade variety, C. fremontii var. riehlii Erickson. Interestingly, two disjunct populations of C. fremontii inhabit cedar glades have been recently located in Rome, GA and Chattanooga, TN. Initially, the focus of my research was to gain insight into whether the two eastern populations are recent introductions or disjunct relict populations.;The discovery of these populations and North American Clematis taxonomy is the subject of Part 1 of this thesis. The second part of this thesis describes a survey of highly variable chloroplast DNA regions that led to the conclusion that chloroplast DNA does not contain enough variability to distinguish populations of C. fremontii. Because previous studies showed that nuclear ribosomal (ITS) sequences were variable at the population level in C. fremontii, sequences from this nrDNA gene region were generated directly from PCR products. The third part is the centerpiece of my research and includes a description of the heterozygosity observed among directly sequenced PCR products, the uncovering of pseudogenes, the myriad alleles uncovered through a massive cloning effort, and is a cautionary description about the shortcomings of this gene region, especially for studies below the level of subgenus. Unexpectedly, it appears that a couple of paralogous pseudogenes may allude to the eastern populations being related to a population in Missouri. Since nrDNA ITS sequences proved inadequate for revealing population relatedness among populations of C. fremontii, the fourth part is a preliminary investigation of the same populations using single-copy nuclear gene glyceraldehyde 3-phosphate dehydrogenase (G3pdh) sequence data. While the data set for this gene region is incomplete, it appears that G3pdh is single copy in Clematis fremontii and variable enough to get at the original goals of this thesis project. The last part of this thesis is an attempt to focus a conservation effort on the Tennessee plants, located entirely on private and commercially zoned property, so that the majority of the genetic diversity of this population can be transferred to a protected site on state lands.