Inferring the population structure and admixture history of three Hmong-Mien-speaking Miao tribes from southwest China based on genome-wide SNP genotyping

Background: Hmong-Mien speaking Miao, also called Hmong, is the sixth largest ethnic group in mainland China. However, the fine-scale genetic profiles and population history of Miao populations in southwest China, especially in Guizhou province, remain uncharacterised due to a scarcity of samples of genome-wide data from different tribes. Aim: To further investigate the population substructure and admixture history of the Guizhou Miao minority. Subjects and methods: We collected 29 samples from three Miao tribes of Guizhou province in southwest China and genotyped about 700,000 genome-wide SNPs of each sample. We analysed newly generated data in together with published modern/ancient East Asian populations datasets via a series of population genetic methods, including principal component analysis (PCA), ADMIXTURE, Fst, TreeMix, f-statistics, qpWave, and qpAdm. Results: PCA and ADMIXTURE results showed that the three studied Guizhou Miao groups consistently fell on the Hmong-Mien-related genetic cline and were relatively genetically homogeneous, displaying a genetic affinity with neighbouring Tai-Kadai speaking populations such as Dong. These results were further confirmed by the observed genetic clade in Fst, TreeMix, outgroup-f3-statistics, and f4-statistics. Furthermore, f4-based allele sharing patterns illustrated that compared with Hunan Miao in central China, Guizhou Miao shared more alleles with Hmong-Mien-speaking Vietnam Hmong and Tai-Kadai-speaking CoLao, Dong, while exhibiting less northeast Asian-related ancestry. Admixture-f3 and f4-statistics revealed the North-South admixture pattern for the studied Guizhou Miao. A qpAdm-based two-way admixture model further revealed that the studied Guizhou Miao harboured 44%-55.4% indigenous Austronesian-speaking Atayal-related ancestry and 44.6%-56% Late Neolithic Yellow River farmer-related ancestry. Conclusions: The population structure within Hmong-Mien-related populations showed a geographic correlation. Hmong-Mien speaking Hunan Miao, Guizhou Miao, and Vietnam Hmong presented close genetic relationships although they dwelt in different regions, suggesting the preservation of the original Hmong-related genetic diversity. The results based on genome-wide SNPs data generally matched the migration history for the Miao population. Our study contributes to a better knowledge of Miao populations and the population structure in southwest China