Beck, James , Schaal, Barbara .
Global population genetics of Arabidopsis thaliana (Brassicaceae).
ARABIDOPSIS thaliana (Brassicaceae) is the preeminent plant model organism, and increasingly a focus of evolutionary and ecological research. Surprisingly, no extensive range-wide study of within and between population genetic variation has been published. We present an analysis of sequence variation at the chloroplast trnL-trnF intergenic spacer and the nuclear Atmyb2 flanking region and PISTILLATA IVS 1 intron in 480 individuals from 155 populations. Sampling was especially dense in proposed Pleistocene refugial areas of Iberia, the Balkans, the Caucasus, and Central Asia. Atmby2 and PISTILLATA haplotype networks were rooted with outgroup sequences in order to identify the ancestral portion of A. thalianaís range. The geographic distributions of inferred ancestral haplotypes at both loci suggest that Europe, as opposed to Central Asia, is the ancestral portion of the range. Geographic structuring according to proposed Pleistocene refugia was investigated with Fisherís exact tests on allele frequencies at the Atmby2 and trnL-trnF regions. Alleles were non-randomly distributed between refugia in 18 of 20 possible pairwise comparisons, indicating significant differentiation among these areas. Finally, among populations for which at least six individuals were analyzed, 45% and 63% exhibited multiple haplotypes at the trnL-trnF and Atmby2 regions, respectively. This lack of fixation is consistent with recent work suggesting that A. thaliana evolved self-compatibility relatively recently.
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1 - Washington University, Biology, Campus Box 1229, 1 Brookings Drive, St. Louis, Missouri, 63130-4899, USA
Presentation Type: Oral Paper:Papers for Topics
Date: Monday, July 31st, 2006
Time: 8:30 AM