Systematics Section / ASPT
Chung, Kuo-fang , Peng, Ching-I , Schaal, Barbara A. .
Biogeography of the Trans-Pacific Alpine Genus Oreomyrrhis (Apiaceae): Insights from Phylogenetics and Phylogeographic Studies.
The plant communities that occur above treeline constitute the alpine biome, the only terrestrial ecosystem that is distributed globally. Understanding the biogeography of plant species in this widespread ecosystem will provide insight into the origins of global biodiversity. Recent studies in Europe suggest that Pleistocene glaciations, landscape heterogeneity, and dispersal dynamics have been the major factors shaping the geographic distribution and genetic variation of alpine plants. However, few studies have attempted to examine these processes on a global scale outside of Europe. The trans-Pacific genus Oreomyrrhis, found in isolated alpine systems of different South Pacific latitudes, presents an ideal system to study alpine biogeography on a global scale. A phylogeny of Oreomyrrhis based on nuclear ITS data places Oreomyrrhis into Subtribe Scandicinae of tribe Scandiceae, Apiaceae. Within Scandicinae, Oreomyrrhis is nested within Chaerophyllum and, along with North American C. procumbens and C. tainturieri, forms a monophyletic clade. Low sequence divergence and poorly resolved phylogenetic relationships suggest a recent origin for Oreomyrrhis and support long-distance dispersal as a biogeographic hypothesis. These data are inconsistent with a vicariant scenario that invokes landbridges or the breakup of Gondwanaland to explain geographic distribution. Preliminary phylogeographic studies of Taiwanese Oreomyrrhis using the chloroplast atpB-rbcL intergenic spacer region reveals high genetic variation and low geographic structure for the haplotypes sampled. These findings support the predictions of the displacement refugia model which postulates that repeated population range expansion and contraction in response to glacial cycles have produced low phylogeographic structure and little population subdivision among current alpine populations.
1 - Missouri Botanical Garden, Graduate Study Program, P.O. Box 299, St. Louis, Missouri, 63166-0299, USA
2 - Academia Sinica, Institute of Botany, Taipei, 11529, Taiwan
3 - Washington University, Department of Biology, 1 Brookings Drive, Rebstock Hall, St. Louis, Missouri, 63130-4899, USA
Presentation Type: Paper
Location: Cottonwood A (Snowbird Center)
Date: Wednesday, August 4th, 2004
Time: 11:00 AM