Beck James B, Schmuths Heike, Schaal Barbara A
Department of Biology, Washington University, St Louis, MO 63130, USA.
Mol Ecol. 2008 Feb;17(3):902-15. doi: 10.1111/j.1365-294X.2007.03615.x. Epub 2007 Dec 20.
Despite Arabidopsis thaliana's pre-eminence as a model organism, major questions remain regarding the geographic structure of its genetic variation due to the geographically incomplete sample set available for previous studies. Many of these questions are addressed here with an analysis of genome-wide variation at 10 loci in 475 individuals from 167 globally distributed populations, including many from critical but previously un-sampled regions. Rooted haplotype networks at three loci suggest that A. thaliana arose in the Caucasus region. Identification of large-scale metapopulations indicates clear east-west genetic structure, both within proposed Pleistocene refugia and post-Pleistocene colonized regions. The refugia themselves are genetically differentiated from one another and display elevated levels of within-population genetic diversity relative to recolonized areas. The timing of an inferred demographic expansion coincides with the Eemian interglacial (approximately 120,000 years ago). Taken together, these patterns are strongly suggestive of Pleistocene range dynamics. Spatial autocorrelation analyses indicate that isolation by distance is pervasive at all hierarchical levels, but that it is reduced in portions of Europe.
尽管拟南芥作为模式生物地位卓越，但由于先前研究可用的地理样本集不完整，其遗传变异的地理结构仍存在重大问题。本文通过分析来自全球167个分布种群的475个个体在10个基因座上的全基因组变异来解决其中许多问题，这些种群包括许多来自关键但先前未采样地区的样本。三个基因座的有根单倍型网络表明，拟南芥起源于高加索地区。大规模集合种群的识别表明，在推测的更新世避难所和更新世后殖民地区内，都存在明显的东西向遗传结构。这些避难所本身在遗传上彼此有差异，并且相对于重新殖民的地区，其种群内遗传多样性水平较高。推断的人口扩张时间与埃姆间冰期（约12万年前）一致。综合来看，这些模式强烈暗示了更新世的范围动态。空间自相关分析表明，距离隔离在所有层次水平上都普遍存在，但在欧洲部分地区有所减少。
