Barbieri Chiara, Hübner Alexander, Macholdt Enrico, Ni Shengyu, Lippold Sebastian, Schröder Roland, Mpoloka Sununguko Wata, Purps Josephine, Roewer Lutz, Stoneking Mark, Pakendorf Brigitte
Department of Evolutionary Genetics, Max Planck Institute for Evolutionary Anthropology, 04103, Leipzig, Germany.
Department of Linguistic and Cultural Evolution, Max Planck Institute for the Science of Human History, 07745, Jena, Germany.
Hum Genet. 2016 May;135(5):541-553. doi: 10.1007/s00439-016-1651-0. Epub 2016 Apr 4.
The recent availability of large-scale sequence data for the human Y chromosome has revolutionized analyses of and insights gained from this non-recombining, paternally inherited chromosome. However, the studies to date focus on Eurasian variation, and hence the diversity of early-diverging branches found in Africa has not been adequately documented. Here, we analyze over 900 kb of Y chromosome sequence obtained from 547 individuals from southern African Khoisan- and Bantu-speaking populations, identifying 232 new sequences from basal haplogroups A and B. We identify new clades in the phylogeny, an older age for the root, and substantially older ages for some individual haplogroups. Furthermore, while haplogroup B2a is traditionally associated with the spread of Bantu speakers, we find that it probably also existed in Khoisan groups before the arrival of Bantu speakers. Finally, there is pronounced variation in branch length between major haplogroups; in particular, haplogroups associated with Bantu speakers have significantly longer branches. Technical artifacts cannot explain this branch length variation, which instead likely reflects aspects of the demographic history of Bantu speakers, such as recent population expansion and an older average paternal age. The influence of demographic factors on branch length variation has broader implications both for the human Y phylogeny and for similar analyses of other species.
人类Y染色体大规模序列数据的近期可得性，彻底改变了对这条非重组、父系遗传染色体的分析及从中获得的见解。然而，迄今为止的研究聚焦于欧亚大陆的变异，因此非洲早期分化分支的多样性尚未得到充分记录。在这里，我们分析了从南部非洲讲科伊桑语和班图语的人群中547个个体获得的超过900 kb的Y染色体序列，从基础单倍群A和B中鉴定出232个新序列。我们在系统发育中识别出新的分支，确定了根的更古老年龄以及一些单个单倍群的更古老得多的年龄。此外，虽然传统上认为单倍群B2a与班图语使用者的扩散有关，但我们发现它可能在班图语使用者到来之前就已存在于科伊桑群体中。最后，主要单倍群之间的分支长度存在显著差异；特别是，与班图语使用者相关的单倍群具有明显更长的分支。技术假象无法解释这种分支长度差异，相反，它可能反映了班图语使用者人口历史的一些方面，例如近期的人口扩张和更高的平均父系年龄。人口因素对分支长度差异的影响，对人类Y染色体系统发育以及对其他物种的类似分析都具有更广泛的意义。
