Valente, Matthew J. , Williams, Joseph H. .
Clonality and genetic diversity revealed by AFLPs in Schisandra glabra (Schisandraceae), a rare basal angiosperm.
Rare species with fragmented distributions often exhibit reduced levels of genetic diversity within populations. However, life history traits such as long lived perennial habit and outcrossing mating system, are associated with high levels of within species genetic variation being partitioned within populations. Schisandra glabra (Schisandraceae) is a rare basal angiosperm with a fragmented distribution across the southeastern US and in a disjunct population in cloudforest of Mexico. The speciesí clonal reproduction by rhizomes, confounds the delineation of genetically distinct individuals in the field. The patterns of genetic diversity and clonality in 10 populations of S. glabra were investigated using AFLP markers. We found a surprising number of distinct genetic individuals in the two populations sampled on 3m grids, with 31 unique genotypes out of 42 samples at Wolfpen Creek, KY, and unique genotypes in all 48 samples from Panther Creek, GA. AMOVA of 237 individuals from 10 populations revealed that the largest portion of the genetic variation is found within populations (58.0%; P<0.0001), and 27.7% (P<0.0001) of the genetic variation is partitioned between the US and Mexico S. glabra populations. Population structure was detected between the US and Mexico populations, but no structure was found between the majority of the US populations. The genetic differentiation of the disjunct population in Mexico, may be the result of a Pliocene or Miocene vicariance hypothesized for many species with similar distributions. The high levels of genetic diversity found within populations are evidence of historical gene flow between the US populations, and the preservation of genetic diversity by the long lived species in its present fragmented distribution.
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1 - University of Tennessee, Department of Geography, 304 Burchfiel Geography Building, Knoxville, TN, 37996-0925, USA
2 - University of Tennessee, Department of Ecology and Evolutionary Biology, 442 Hesler Biology, Knoxville, Tennesee, 37996, USA
Presentation Type: Oral Paper:Papers for Sections
Location: 182/I K Barber
Date: Monday, July 28th, 2008
Time: 8:30 AM