| Abstract Detail
Biogeography Price, Taina M. [1]. Phemeranthus: Phylogeography in arid North America. Plant species exhibit a broad spectrum of geographic distributions. While some are nearly cosmopolitan, others are confined to one or a few localities in a specific habitat. Moreover, there are numerous examples of closely related species that differ in range size and habitat specificity. Species with restricted geographic distributions are of great interest to evolutionary biology, as they may provide insight into the conditions promoting the origin, geographic spread, persistence, or extinction of taxa through time. Phemeranthus Raf. (Portulacaceae) provides a case study for these processes in North Temperate arid zones. Phemeranthus includes approximately 27 species of succulent, herbaceous perennials with terete leaves and fleshy roots. Some are widespread in North America, while others are endemic to one or a few localities. All are restricted to shallow or sandy soils, often on rock outcrops. Some appear to be edaphic specialists, while others occur on a relatively wide range of soil types. The species vary in breeding system and in ploidy level. A variety of speciation processes have apparently occurred in Phemeranthus, including allopolyploid and autopolyploid speciation. Phemeranthus exhibits a biogeographic pattern similar to that of numerous other taxa of arid western North America. The center of diversity of the genus is in northern Mexico and the southwestern United States. Geographic disjunctions occur between P. punae of northern Argentina and the remainder of the genus; between the two species of Oregon and Washington and the remaining North American species; and among populations of P. rugospermus and P. parviflorus, two widespread species of the Midwestern United States. Molecular phylogentic studies in Phemeranthus will provide a foundation for investigations of a variety of questions regarding character evolution and biogeography in this interesting genus.
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1 - Washington University in St. Louis, Biology, Campus Box 1137, 1 Brookings Drive, St. Louis, MO, 63130, United States
Keywords:
Phemeranthus
Portulacaceae
phylogeny
phylogeography
range size
endemism
western North America.
Presentation Type: Poster:Posters for Topics
Session: P
Location: Exhibit Hall (Northeast, Southwest & Southeast)/Hilton
Date: Sunday, July 8th, 2007
Time: 8:00 AM
Number: P62007
Abstract ID:1961 |
