Systematics Section / ASPT
Taylor, Sarah J. , Simpson, Beryl .
Phylogenetic relationships and the evolution of gypsophily within the genus Nama (Hydrophyllaceae).
Gypsum (hydrated calcium sulfate) deposits form a common substrate in warm, dry regions of the world, including Mexico, the southwestern United States, portions of Africa, Europe, South America, and western Australia. Many unusual endemic species and species-rich communities have evolved on these deposits, especially in the north-central region of Mexico. While it is obvious that gypsophily arose independently in many different genera, it is not clear whether there are single or multiple origins within those genera that contain numerous gypsum-adapted species. Six species of Nama, a New World genus comprising approximately 50 species within the Hydrophyllaceae and occurring mainly in the desert areas of the southwestern United States and adjacent Mexico, exhibit varying degrees of gypsophily. Preliminary evidence from phylogenetic reconstructions using nuclear (ITS 1&2) and cpDNA (matK) markers suggests there may have been multiple origins of gypsophily in Nama rather than a single origin followed by rapid radiation. We use these same phylogenetic hypotheses to assess relationships previously inferred using morphological characters.
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1 - Universtiy of Texas Austin, Section of Integrative Biology, 1 University Station, A6720, Austin, Texas, 78712, USA
2 - University of Texas Austin, Section of Integrative Biology, 1 University Station, A6700, Austin, Texas, 78712-7640, USA
Presentation Type: Oral Paper
Location: Salon G - Austin Grand Ballroom/Hilton
Date: Wednesday, August 17th, 2005
Time: 2:30 PM