Bakker E G, Stahl E A, Toomajian C, Nordborg M, Kreitman M, Bergelson J
Department of Ecology and Evolution, University of Chicago, Chicago, IL 60637, USA.
Mol Ecol. 2006 Apr;15(5):1405-18. doi: 10.1111/j.1365-294X.2006.02884.x.
A detailed description of local population structure in Arabidopsis thaliana is presented, including an assessment of the genetic relatedness of individuals collected from the same field. A hierarchical sample of four individuals from 37 local populations, including North America, England, Eastern and Western Europe, and Asia, and a selection of ecotypes, were analysed for variation in Adh, ChiA, FAH1, F3H, Rpm1, Rps5, and five microsatellite loci. Twenty-eight of the 37 population samples contained individuals with identical multilocus haplotypes, 12 of which were fixed for a single haplotype. These monomorphic populations were evenly distributed over the species range. Only in North America did we find a single multilocus haplotype shared among different populations, perhaps indicating a continental founder event. Despite the occurrence of local inbreeding, a considerable amount of genetic variation was found segregating within and among local populations. A novel analysis of haplotype differences reveals that genetic differentiation occurs at every geographic scale in A. thaliana, where we find a surprising under-representation of recent migrants between local populations. This leads us to hypothesize that most dispersal between A. thaliana populations is by pollen rather than seed. Based on the structure of A. thaliana populations, it appears that regional groups of local populations may provide the most appropriate genetic material for linkage disequilibrium mapping of adaptive traits.
本文详细描述了拟南芥的本地种群结构，包括对从同一田地采集的个体间遗传相关性的评估。对来自北美、英国、东欧和西欧以及亚洲的37个本地种群中的4个个体组成的分层样本，以及一些生态型，分析了乙醇脱氢酶（Adh）、几丁质酶A（ChiA）、脂肪酸羟化酶1（FAH1）、黄烷酮3-羟化酶（F3H）、抗病基因Rpm1、Rps5以及5个微卫星位点的变异情况。37个种群样本中有28个包含具有相同多位点单倍型的个体，其中12个种群固定为单一单倍型。这些单态种群在物种分布范围内均匀分布。仅在北美，我们发现不同种群间共享一种多位点单倍型，这可能表明存在一次大陆奠基者事件。尽管存在本地近亲繁殖现象，但在本地种群内部和之间仍发现有大量遗传变异在分离。对单倍型差异的一项新分析表明，拟南芥在每个地理尺度上都发生了遗传分化，我们发现本地种群间近期迁移个体的比例惊人地低。这使我们推测，拟南芥种群间的大多数扩散是通过花粉而非种子进行的。基于拟南芥种群的结构，似乎本地种群的区域组可能为适应性性状的连锁不平衡作图提供最合适的遗传材料。
