XVI International Botanical Congess

Pityopsis ruthii is a perennial herb in the Asteraceae endemic to phyllite outcrops along the Hiwassee and Ocoee rivers in Polk County, TN. Although the range of P. ruthii is believed to have been unchanged in recent history, the more distant historical distribution of this species is unknown. Previous work using isozymes has provided a description of current population genetic structure as well as estimates of gene flow among extant populations. In order to assess the influence of historic processes on current genetic structure of P. ruthii populations, a phylogeographic study of cpDNA variation was undertaken. Chloroplast DNA variation was assayed using PCR-RFLP of ten hypervariable regions of the chloroplast genome. Our results illustrate how phylogeographic methods can be used to gain an increased understanding of the historical distribution of endemic species.