Phylogeography of the human mitochondrial L1c haplogroup: Genetic signatures of the prehistory of Central Africa
Phylogeography of the human mitochondrial L1c haplogroup: Genetic signatures of the prehistory of Central Africa
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DOI：
10.1016/j.ympev.2006.09.014
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发表时间：
2007-05-01
影响因子：
4.1
通讯作者：
Calafell, Francesc
中科院分区：
文献类型：
--
作者：
Batini, Chiara;Coia, Valentina;Calafell, Francesc
在过去的二十年里，人类线粒体 DNA 的个体间变异得到了广泛的研究，其对于重建现存种群进化关系的有用性已得到证明。然而，一些线粒体谱系仍然需要结合使用更大和定制的数据集以及提高的分辨率水平来研究，以便阐明它们的起源和它们目前分布的过程。在这项研究中，我们使用来自撒哈拉以南非洲和非裔美国人群体的 455 名个体（从总共 2542 名个体中提取）获得的高变区 I 和 2 的序列数据，分析了人类线粒体 DNA L1c 单倍群的系统发育。我们提出对 L1c 系统发育进行重大修订，引入一个新的亚单倍群 (L1c4)、两个新的 L1c1 分支（L1c1b 和 L1c1c），并将之前的 L1c1a1 序列重新分配给我们称为 L1c5 的分支。新的系统发育包括具有不同进化历史的不同谱系。事实上，根据种群频率、内部变异和错配分布，我们认为L1c1b、L1c1c和L1c2起源于班图人祖先，而L1c1a、L1c4和L1c5在西方俾格米人中进化。 L1c 的群体结构无法与任何已知的线粒体甚至 Y 染色体单倍群相比较，并且挑战了当前的观点，即俾格米人的大多数线粒体 DNA 变异可能反映了与班图人的混合或类似形特征的持续存在。事实上，L1c 的独特之处在于它保留了班图人和西方俾格米人祖先共同的阶段特征，同时包含一些可以表明它们分歧的特定子分支。这使我们能够尝试对两个群体之间的进化关系进行基于系统发育的评估。考虑到对 L1c 及其分支最近共同祖先的时间估计以及考古和古气候学证据，我们建议班图人和西部俾格米人的祖先相距 60 至 30 kya。 (C) 2006 Elsevier Inc. 保留所有权利。
Interindividual variation of human mitochondrial DNA has been extensively studied over the last two decades, and its usefulness for reconstructing evolutionary relationships of extant populations has been proved. However, some mitochondrial lineages still need to be studied using a combination of larger and tailored datasets and increased level of resolution in order to shed light on their origin and on the processes underlying their present distribution. In this study, we analyze the phylogeny of the L1c haplogroup of human mitochondrial DNA using sequence data from hypervariable regions I and 2 obtained from 455 individuals (extracted from a total sampling of 2542 individuals) belonging to sub-Saharan African and African-American populations. We propose a substantial revision of L1c phylogeny, by introducing one new sub-haplogroup (L1c4), two new L1c1 clades (L1c1b and L1c1c), and by reassigning the previous L1c1a1 sequences to a clade which we termed L1c5. The new phylogeny encompasses distinct lineages with different evolutionary histories. In fact, based on population frequency, internal variation and mismatch distribution, we propose that L1c1b, L1c1c and L1c2 originated in Bantu ancestors, whereas L1c1a, L1c4 and L1c5 evolved among Western Pygmies. The population structure of L1c is not comparable to any known mitochondrial or, even, Y-chromosomal haplogroup, and challenges the current view that most of mtDNA variation in Pygmies might reflect admixture with Bantu or a persistence of plesiomorphic characters. In fact, the unique feature of the L1c is that it retains a signature of a phase common to the ancestors of the Bantu and Western Pygmies, while encompassing some specific sub-clades which can indicate their divergence. This allowed us to attempt a phylogenetically based assessment of the evolutionary relationships between the two groups. Taking into consideration estimates of the time to the most recent common ancestor of L1c and its clades together with archaeological and paleoclimatological evidence, we propose that the ancestors of Bantu and Western Pygmies separated between 60 and 30 kya. (C) 2006 Elsevier Inc. All rights reserved.