Institute of Forensic Medicine, West China School of Basic Science & Forensic Medicine, Sichuan University, Chengdu 610041, China.
Forensic Identification Center, Public Security Bureau of Tibet Tibetan Autonomous Region, Lhasa, Tibet Tibetan Autonomous Region, 850000, China.
Forensic Sci Int Genet. 2020 Jul;47:102303. doi: 10.1016/j.fsigen.2020.102303. Epub 2020 Apr 22.
As a single maternally inherited locus, human mitochondrial DNA (mtDNA) is geographically arranged and plays a key role in forensic applications. Hlai population has been evidenced as the most typical and unmixed representative of the Tai-Kadai-speaking populations via genome-wide analyses. However, forensic features and maternal diversity of the complete mitogenomes in this Tai-Kadai ancestrally related population are scarce. Thus, we sequenced the complete mitogenomes in 127 Hainan Hlais and found 109 distinct haplotypes belonging to 43 terminal haplogroups resulting in the haplotype diversity of 0.9970. Our results of comprehensive population comparisons showed that Hlai islanders had a close genetic affinity with Tai-Kadai-speaking populations from Southeast Asia, which is consistent with the back-migration of Chinese Neolithic farmers into this region via the inland route. Besides, maternally genetic evidence further revealed a close genetic relationship between Tai-Kadai-speaking and Austronesian-speaking populations when only East Asian dataset was considered, which is consistent with the common origin from Yangtze rice farmers and then spread southward along the inland and coastal routes, respectively. In the reconstructed phylogenetic tree and median-joining networks, the vast majority of Hlais were clustered in exclusive clades, which demonstrated that Hlai people probably had undergone founder effect or genetic bottleneck in their history, and remained genetically isolated for a long time. Collectively, Hainan Hlai did not exhibit detectable maternal gene flow from surrounding or incoming populations. Mitogenome information generated in this study is a contribution in mitigating the underrepresentation of Chinese data in forensic mitogenetics and will assist geography-, metapopulation-, as well as phylogeny-based queries.
作为一个单一的母系遗传基因座，人类线粒体 DNA（mtDNA）具有地理排列，在法医应用中起着关键作用。通过全基因组分析，已证实 Hlai 群体是泰语族中最典型和未混合的代表。然而，在这个与泰语族有关的群体中，完整线粒体基因组的法医特征和母系多样性却很少。因此，我们对 127 名海南 Hlai 进行了完整线粒体基因组测序，发现了 109 个独特的单倍型，属于 43 个末端单倍群，导致单倍型多样性为 0.9970。我们的综合人群比较结果表明，Hlai 岛民与东南亚的泰语族人群具有密切的遗传亲和力，这与中国新石器时代农民通过内陆路线向该地区的回迁一致。此外，当仅考虑东亚数据集时，母系遗传证据进一步表明，泰语族和南岛语族人群之间存在密切的遗传关系，这与从长江稻农起源，然后分别沿着内陆和沿海路线向南传播的说法一致。在重建的系统发育树和中位数连接网络中，绝大多数 Hlai 被聚类在独特的分支中，这表明 Hlai 人可能在其历史上经历了奠基者效应或遗传瓶颈，并且长期保持遗传隔离。总的来说，海南 Hlai 没有表现出可检测到的来自周围或迁入人群的母系基因流。本研究中产生的线粒体基因组信息有助于减轻中国数据在法医线粒体遗传学中的代表性不足，并将有助于地理、复合种群以及系统发育查询。
