Li Haipeng, Stephan Wolfgang
Section of Evolutionary Biology, Department of Biology II, University of Munich, Planegg-Martinsried, Germany.
PLoS Genet. 2006 Oct 13;2(10):e166. doi: 10.1371/journal.pgen.0020166. Epub 2006 Aug 17.
An important goal of population genetics is to determine the forces that have shaped the pattern of genetic variation in natural populations. We developed a maximum likelihood method that allows us to infer demographic changes and detect recent positive selection (selective sweeps) in populations of varying size from DNA polymorphism data. Applying this approach to single nucleotide polymorphism data at more than 250 noncoding loci on the X chromosome of Drosophila melanogaster from an (ancestral) African population and a (derived) European, we found that the African population expanded about 60,000 y ago and that the European population split off from the African lineage about 15,800 y ago, thereby suffering a severe population size bottleneck. We estimated that about 160 beneficial mutations (with selection coefficients s between 0.05% and 0.5%) were fixed in the euchromatic portion of the X in the African population since population size expansion, and about 60 mutations (with s around 0.5%) in the diverging European lineage.
群体遗传学的一个重要目标是确定塑造自然群体中遗传变异模式的各种力量。我们开发了一种最大似然法，该方法使我们能够从DNA多态性数据推断不同规模群体的人口统计学变化并检测近期的正选择（选择性清除）。将此方法应用于来自（祖先）非洲群体以及（衍生）欧洲群体的黑腹果蝇X染色体上250多个非编码位点的单核苷酸多态性数据，我们发现非洲群体在约6万年前扩张，欧洲群体在约1.58万年前从非洲谱系中分离出来，因此经历了严重的群体规模瓶颈。我们估计，自群体规模扩张以来，非洲群体中约160个有益突变（选择系数s在0.05%至0.5%之间）在X染色体的常染色质部分固定下来，而在分化的欧洲谱系中约有60个突变（s约为0.5%）。
