Zietkiewicz E, Yotova V, Jarnik M, Korab-Laskowska M, Kidd K K, Modiano D, Scozzari R, Stoneking M, Tishkoff S, Batzer M, Labuda D
Centre de Recherche de l'Hôpital Sainte-Justine, Centre de Cancérologie Charles Bruneau, Département de Pédiatrie, Université de Montréal, Montréal, Québec, H3T-1C5 Canada.
J Mol Evol. 1998 Aug;47(2):146-55. doi: 10.1007/pl00006371.
Neutral DNA polymorphisms from an 8-kb segment of the dystrophin gene, previously ascertained in a worldwide sample (n = 250 chromosomes), were used to characterize the population ancestral to the present-day human groups. The ancestral state of each polymorphic site was determined by comparing human variants with their orthologous sites in the great apes. The "age before fixation" of the underlying mutations was estimated from the frequencies of the new alleles and analyzed in the context of these polymorphisms' distribution among 13 populations from Africa, Europe, Asia, New Guinea, and the Americas (n = 860 chromosomes in total). Seventeen polymorphisms older tan 100,000-200,000 years, which contributed approximately 90% to the overall nucleotide diversity, were common to all human groups. Polymorphisms endemic to human groups or continentally restricted were younger than 100,000-200,000 years. Africans (six populations) with 13 such sites stood out from the rest of the world (seven populations), where only 2 population-specific variants were observed. The similarity of the frequencies of the old polymorphisms in Africans and non-Africans suggested a similar profile of genetic variability in the population before the modern human's divergence. This ancestral population was characterized by an effective size of about 10,000 as estimated from the nucleotide diversity; this size may describe the number of breeding individuals over a long time during the Middle Pleistocene or reflect a speciation bottleneck from an initially larger population at the end of this period.
肌营养不良蛋白基因8kb片段中的中性DNA多态性，此前在一个全球样本（n = 250条染色体）中已确定，被用于刻画当今人类群体的祖先群体特征。通过将人类变体与其在大猩猩中的直系同源位点进行比较，确定每个多态性位点的祖先状态。根据新等位基因的频率估计潜在突变的“固定前年龄”，并结合这些多态性在来自非洲、欧洲、亚洲、新几内亚和美洲的13个群体中的分布情况进行分析（总共n = 860条染色体）。17个年龄超过10万至20万年的多态性，它们对总体核苷酸多样性的贡献约为90%，在所有人类群体中都很常见。人类群体特有的或在大陆范围内受限的多态性年龄小于10万至20万年。拥有13个此类位点的非洲人（6个群体）与世界其他地区（7个群体）不同，在世界其他地区仅观察到2个群体特异性变体。非洲人和非非洲人古老多态性频率的相似性表明，在现代人类分化之前，该群体的遗传变异情况相似。根据核苷酸多样性估计，这个祖先群体的有效大小约为10000；这个大小可能描述了中更新世期间很长一段时间内的繁殖个体数量，或者反映了该时期末从最初较大群体形成物种时的瓶颈效应。
