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Genetic Diversity of Primates and The Future of Man

灵长类动物的遗传多样性和人类的未来

基本信息

批准号：
08404052
负责人：
TAKAHATA Naoyuki
金额：
$ 17.98万
依托单位：
The Graduate University for Advanced Studies
依托单位国家：
日本
项目类别：
Grant-in-Aid for Scientific Research (A).
财政年份：
1996
资助国家：
日本
起止时间：
1996 至 1999
项目状态：
已结题

项目摘要

(1) In, collaboration with Dr. Jan Klein in Max-Plank-Institut fur Biologie (Tubingen), the principal investigator (N. T.) has been co-authoring a popular science book for these four years. The book is entitled "Where do we come from? The molecular evidence for human descent" and is composed of 10 chapters. This year, the PI visited the MPI for three weeks to discuss the whole contents and write Chapter 6-10. The book covers several fields of biology, such as molecular biology, population genetics, anthropology, evolutionary genetics, and primatology. Many results obtained through this research project will be reproduced in the book. By the end of this calendar year, the book is planned to be distributed worldwide.(2) In general, neutral genes in the human population exhibit relatively shallow genealogies. The time scale of such genealogies is of the order of N generations, where N is the effective population size and estimated as 10,000 during the Pleistocene. A notable exception is t … More hose genes, which are linked to the Major Histocompatibility Complex (Mhc) loci. The genealogy at these linked neutral loci is much deeper than that of unlinked neutral genes. This, deep genealogy and high extent of nucleotide diversity result from linkage effects of balancing selection at Mhc loci. The nucleotide diversity of linked genes decreases, as the recombination rate between an Mhc locus and a linked neutral locus increases. Conversely, under an appropriate population genetics model, it is possible to estimate the recombination rate from the observed extent of the nucleotide diversity at a linked neutral locus. We have applied this principle to the human Mhc (HLA) region. The result shows that the recombination rate is generally 1 cM per 1 Mb, but it fluctuates considerably from locus to locus. In particular, the genomic region telomeric to the HLA-A locus is subjected to extremely infrequent recombination.(3) We have expanded our previous analysis about the demographic history of human lineages during the entire period of primate evolution. We have constructed aDNA sequence database comprising of 45 sets of orthologous nucleotide sequences among the human, the chimpanzee, and the gorilla. It is confirmed that the chimpanzee is the closest relative to the human. However, individual sets of genes can support this conclusion only weakly. This weak support mainly stems from the presence of phylogenetically incompatible sites in an individual set of DNA sequences. The major cause of such sequence incompatibility is not due to homoplasy, but due to intragenic recombination among ancestral sequences. The trichotomy problem among the human, the chimpanzee, and the gorilla, or more generally among relatively closely related species can properly be addressed only within this framework. Less

首席研究员（n.t.）与图宾根马克斯-普朗克生物研究所的简·克莱因博士（Dr. Jan Klein）合作，四年来一直在合著一本科普书籍。这本书的题目是《我们从哪里来？》《人类起源的分子证据》一书共分10章。今年，PI访问了MPI三周，讨论了整个内容，并撰写了第6-10章。这本书涵盖了生物学的几个领域，如分子生物学，人口遗传学，人类学，进化遗传学和灵长类学。通过这项研究项目获得的许多结果将在书中转载。到今年年底，这本书计划在全球发行。(2)一般来说，中性基因在人类群体中表现出相对较浅的谱系。这种谱系的时间尺度大约为N代，其中N为有效种群规模，估计更新世时期为10,000人。一个值得注意的例外是更多的这些基因，它们与主要组织相容性复合体（Mhc）位点相连。这些连接的中性基因位点的家谱比未连接的中性基因要深得多。这是因为在Mhc位点上平衡选择的连锁效应导致了深厚的谱系和高度的核苷酸多样性。随着Mhc位点与连锁中性位点之间的重组率增加，连锁基因的核苷酸多样性降低。相反，在适当的群体遗传学模型下，可以从观察到的连锁中性位点的核苷酸多样性程度来估计重组率。我们已经将这一原理应用于人类Mhc （HLA）区域。结果表明，重组率一般为1 cM / 1 Mb，但不同基因座间的重组率波动较大。特别是，HLA-A位点的基因组区域端粒受到极其罕见的重组。(3)我们扩展了先前对灵长类动物进化整个时期人类谱系的人口历史的分析。建立了人类、黑猩猩和大猩猩45组同源核苷酸序列的dna序列数据库。经证实，黑猩猩是与人类最近的亲戚。然而，单个基因组只能微弱地支持这一结论。这种微弱的支持主要源于在单个DNA序列中存在系统发育不相容的位点。这种序列不亲和性的主要原因不是由于同源性，而是由于祖先序列之间的基因内重组。人类、黑猩猩和大猩猩之间的三分法问题，或者更普遍地说，在相对密切相关的物种之间的三分法问题，只能在这个框架内得到适当的解决。少