Improved phylogenetic resolution and rapid diversification of Y-chromosome haplogroup K-M526 in Southeast Asia.

The highly structured distribution of Y-chromosome haplogroups suggests that current patterns of variation may be informative of past population processes. However, limited phylogenetic resolution, particularly of subclades within haplogroup K, has obscured the relationships of lineages that are common across Eurasia. Here we genotype 13 new highly informative single-nucleotide polymorphisms in a worldwide sample of 4413 males that carry the derived allele at M526, and reconstruct an NRY haplogroup tree with significantly higher resolution for the major clade within haplogroup K, K-M526. Although K-M526 was previously characterized by a single polytomy of eight major branches, the phylogenetic structure of haplogroup K-M526 is now resolved into four major subclades (K2a-d). The largest of these subclades, K2b, is divided into two clusters: K2b1 and K2b2. K2b1 combines the previously known haplogroups M, S, K-P60 and K-P79, whereas K2b2 comprises haplogroups P and its subhaplogroups Q and R. Interestingly, the monophyletic group formed by haplogroups R and Q, which make up the majority of paternal lineages in Europe, Central Asia and the Americas, represents the only subclade with K2b that is not geographically restricted to Southeast Asia and Oceania. Estimates of the interval times for the branching events between M9 and P295 point to an initial rapid diversification process of K-M526 that likely occurred in Southeast Asia, with subsequent westward expansions of the ancestors of haplogroups R and Q.