Doffitt, Chris , Wallace, Lisa Ellen .
Phylogeographic Structure in A.ciliata (Apocynaceae) .
Despite the great botanical diversity of the Southeast, there have been relatively few phylogeographic studies detailing how environmental factors shape patterns of evolutionary diversification in this region. This study used AFLP markers to clarify intraspecific patterns of divergence in Amsonia ciliata (Apocynaceae), a species that includes three varieties (ciliata, tenuifolia, and texana) and has a range extending from South Carolina to Texas, with populations absent from Mississippi and Louisiana. The discontinuous distribution of A. ciliata across the Southeast suggests that landscape barriers restrict gene flow, potentially promoting divergence. This distribution makes it an ideal study system for testing hypotheses concerning landscape or ecological boundaries and their importance to evolutionary diversification of the southeastern flora. We tested the hypothesis that population genetic structure corresponds to morphological divergence within A. ciliata. An alternative hypothesis is that the species is composed of many metapopulations that exhibit clinal variation across its range. If the genetic patterns correspond to morphological and environmental variation, then it can be assumed that barriers to gene flow are imposed by the landscape and the intraspecific taxonomy would be supported. Samples of A. ciliata from populations of the three varieties have been sampled. The results indicate that there is population structure despite the close proximity of some populations, thereby providing credence to the theory that populations occurring in unique habitats could represent evolutionary significant units. Comparative analyses of morphological features and environmental data extracted in GIS will be discussed in relation to genetic structure. This work will contribute to the growing phylogeographic literature on southeastern plant taxa and is especially important because many populations of A. ciliata occur on limestone glades, which are becoming increasingly rare and harbor many endemic plant species. Thus, in addition to providing important information on distinctiveness and distributions of the varieties of A. ciliata, this work will contribute to setting conservation priorities and implementing management practices for A. ciliata and other glade endemics.
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1 - Mississippi State University, Biological Sciences, P.O. Box GY, Mississippi State, MS, 39762, USA
Presentation Type: Poster:Posters for Topics
Location: Hall A/Convention Center
Date: Monday, August 2nd, 2010
Time: 5:30 PM