Price, Taina M. .
Distribution patterns and genetic relationships of Phemeranthus (Montiaceae) species in the Midwestern United States.
Within the genus Phemeranthus Raf. (Montiaceae), a clade of seven to nine relatively tall, pink- or white- flowered species is broadly distributed in patchy xeric habitats across the Midwestern and Southeastern United States. Several of these species have intriguing patterns of distribution. The prairie fameflower, Phemeranthus rugospermus (Holz.) Kiger, shows particularly striking population disjunctions. While the main part of this species' range is in the upper Midwest, populations have been found in central Nebraska, central Kansas, and east Texas. Several hypotheses have been proposed to explain this patchy distribution. P. rugospermus may have arrived in its present localities via post-glacial long-distance dispersal. Its distribution may be a remnant of a previously widespread range. Or the P. rugospermus morphology may have arisen multiple times, potentially via hybridization between its co-distributed relatives. The morphology of P. rugospermus is intermediate in several respects between that of the small-flowered sunbright, P. parviflorus (Nutt.) Kiger, and that of the large-flowered fameflower, P. calycinus (Engelm.) Kiger. These two species are broadly sympatric and often syntopic across the geographical range of P. rugospermus. Hybrid speciation is known to have occurred within the Eastern North American (ENA) clade of Phemeranthus; chromosomal, morphological, and allozyme data indicate that P. parviflorus is one parent of another allopolyploid species. Chloroplast and nuclear sequence data indicate close relationships among all of the ENA species of Phemeranthus, but show very little divergence among species, making these markers of limited use for phylogeographic questions. We used amplified fragment length polymorphism (AFLP) markers to study the genetic diversity within P. rugospermus and its co-distributed congeners, in an effort to determine the most likely explanation for its present-day patterns of distribution.
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1 - Washington University in St. Louis, Biology, Campus Box 1137, 1 Brookings Drive, St. Louis, MO, 63130, United States
Presentation Type: Oral Paper:Papers for BSA Sections
Location: Magpie A/Cliff Lodge - Level B
Date: Tuesday, July 28th, 2009
Time: 10:45 AM