Phylogeographic analysis of mtDNA variation in four ethnic populations from Yunnan Province: new data and a reappraisal.

Two sets of mitochondrial DNA (mtDNA) hypervariable segment I (HVS-I) data from four ethnic populations (Tibetan, Va, Dai, and Lahu) from Yunnan Province, China, were analyzed here by using phylogeographic methods. The results suggest that more attention should be paid to sampling methodology when addressing the genetic relationship and affinity among ethnic populations. Comparison of related data from different labs may serve as a check for the credibility of the data and will help discern the origin of the ethnic populations. Generally, Tibetan populations have more north-prevalent haplogroups (clades of the mtDNA phylogeny), while Dai and Lahu populations have high frequencies of south-prevalent haplogroups. The Vas, although autochthonous according to historical records, show signs of gene admixtures from northern and southern populations, for they harbor high frequencies of the south-prevalent haplogroup F and the north-prevalent haplogroup D as well as other northern mtDNA lineages such as M9 and G2a. The consanguineous marriage customs of the Lahu, together with possible genetic drift during this group's historical migration, left a conspicuous genetic imprint on its current gene pool.