Systematics Section / ASPT
O'Quinn, Robin , Hufford, Larry .
Biogeographic diversification of Claytonia (Portulacaceae).
Montieae is a small tribe that consists of two genera, Montia and Claytonia. The tribe has its greatest species richness in North America, but also has representatives in South and Central America, northeastern Asia, New Zealand and Australia. In Montieae, Claytonia is an exclusively northern hemisphere clade of ~26 species distributed among the monophyletic sections Limnia, Rhizomatosae and Claytonia. Section Limnia consists of annuals except for the perennials C. sibirica and C. palustris. Sections Rhizomatosae and Claytonia, sister clades in maximum likelihood and Bayesian inference analyses, consist primarily of perennials. Ancestral area reconstruction using DIVA on maximum parsimony and Bayesian inference topologies indicate a western North American origin for Claytonia. The annual taxa are predominantly western North American, extending into high latitudes only in coastal environments. The perennials of sects. Claytonia and Rhizomatosae extend from northern Mexico to northeastern Asia and in eastern American from New Foundland to Texas. Both perennial sections include several endemic Beringian taxa that exhibit largely the Beringian-Arctic disjunction described by Thorne. Our analyses resolve few clades in sect. Claytonia, and DIVA analyses reconstruct considerably different biogeographic changes for sampled cladograms. Although we infer multiple origins for Beringian taxa, reconstructions for dispersal and vicariance are inconclusive. In the better resolved sect. Rhizomatosae a northward migration from low latitude western North America to Beringia produced a northern clade and a southern grade. All taxa of the northern clade are found in both eastern and western Beringia, except C. joanneana, which is restricted to western Beringia (Siberia). This pattern of migration from low latitude western North America through Beringia to northeastern Asia (i.e. east to west) contrasts with the presumed predominant direction of migration (west to east), although various North American taxa also exhibit this east to west pattern of dispersal.
1 - Washington State University, School of Biological Sciences, P.O. Box 644236, Pullman, Washington, 99164-4236
western North America.
Presentation Type: Paper
Location: Cottonwood C (Snowbird Center)
Date: Wednesday, August 4th, 2004
Time: 2:45 PM