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Genetic variation in African populations: A multi-locus approach to understanding selection and demography in humans.

机译：非洲人口的遗传变异：了解人类选择和人口统计学的多场所方法。

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摘要

Mutation, recombination, selection, and demographic processes (such as gene flow and genetic drift) have shaped genetic variation, but the relative impact of these evolutionary forces remains poorly understood. This problem motivates this study which examines three regions of the genome---beta-globin, the Y-chromosome, and mtDNA---in a two part approach to assess the relative impact of evolutionary forces on human genetic variation in Africa. The first approach characterizes levels of nucleotide variability and linkage disequilibrium across the beta-globin gene and recombinational hotspot in a sample of malarial-resistance alleles (HbC and HbS). Results suggest that the age of the HbC allele is 5,000 years and selection coefficients are 0.04-0.09 and, recombination is observed within 1-kb of the selected site on >1/3 of the chromosomes sampled ( Appendix A). A long-standing question regarding the HbS allele is whether it originated multiple times via recurrent mutation or whether it arose once and was transferred to different haplotypic backgrounds through recombination. These results indicate that recombination played a critical role in generating haplotypic diversity at beta-globin and can explain the origins of the Bantu and Senegalese HbS haplotypes (Appendix B). The second approach examines Y-chromosome and mtDNA variation to disentangle the relative effects of demographic forces. A detailed characterization of the Y-chromosome and mtDNA in >1000 individuals from ∼40 populations reveals that patterns of variation from these paternally- and maternally-inherited loci are remarkably different, suggesting that sex-specific demographic processes have influenced African genetic variation, particularly among agriculturalists (Appendix C). Hunter-gatherer populations carry a suite of Y-chromosomes that differ from those of agricultural populations. The examination of Y-SNP and Y-STR variation in eight hunter-gatherer populations reveals the presence of a very old, >50-kya, derived lineage (B2b) shared among these populations, which is absent in agricultural populations, suggesting that hunter-gatherer populations share an ancient common ancestry (Appendix D). Finally, the Y-chromosome results are placed into a broader evolutionary context in a phylogeographic summary as it relates to archeological and linguistic variation in Africa (Appendix E). Together these results underscore the vastly different effects that various evolutionary forces have had on shaping human genetic variation in Africa.
机译：突变，重组，选择和人口统计过程（例如基因流和遗传漂移）已经塑造了遗传变异，但是对这些进化力的相对影响仍然知之甚少。这个问题激发了这项研究的动机，该研究以两部分方法来评估基因组的三个区域-β-球蛋白，Y染色体和mtDNA-来评估进化力对非洲人类遗传变异的相对影响。第一种方法表征了抗疟疾等位基因（HbC和HbS）样本中整个β-珠蛋白基因和重组热点的核苷酸变异性和连锁不平衡水平。结果表明，HbC等位基因的年龄小于5,000岁，选择系数为0.04-0.09，并且在大于1/3的染色体样本中的选定位点的1kb内观察到重组（附录A）。关于HbS等位基因的一个长期存在的问题是它是否是通过重复突变多次起源或是否起源一次并通过重组转移到不同的单倍型背景。这些结果表明，重组在产生β球蛋白的单倍型多样性中起关键作用，并且可以解释班图人和塞内加尔人HbS单倍型的起源（附录B）。第二种方法检查Y染色体和mtDNA的变异，以消除人口统计学力量的相对影响。对来自〜40个人口的1000多个个体中Y染色体和mtDNA的详细表征显示，这些父本和母本遗传的基因座的变异模式显着不同，这表明性别特定的人口统计过程已经影响了非洲的遗传变异，特别是在农业工作者中（附录C）。猎人-采集者种群携带一套与农业种群不同的Y染色体。对8个猎人-采集者种群中Y-SNP和Y-STR变异的检查表明，这些种群中存在非常古老的> 50-kya派生谱系（B2b），而在农业种群中则不存在，这表明猎人-采集者群体具有古老的共同血统（附录D）。最后，Y染色体结果在系统地理学概述中被置于更广泛的进化背景下，因为它与非洲的考古和语言变异有关（附录E）。这些结果共同强调了各种进化力量对塑造非洲人类遗传变异的巨大影响。

著录项

  • 作者

    Wood, Elizabeth T.;

  • 作者单位

    The University of Arizona.;

  • 授予单位 The University of Arizona.;
  • 学科 Anthropology Physical.;Biology Genetics.
  • 学位 Ph.D.
  • 年度 2006
  • 页码 122 p.
  • 总页数 122
  • 原文格式 PDF
  • 正文语种 eng
  • 中图分类 人类学;遗传学;
  • 关键词

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