Population genetic structure in Indian Austroasiatic speakers: the role of landscape barriers and sex-specific admixture

Abstract

The geographic origin and time of dispersal of Austroasiatic (AA) speakers, presently settled in south and southeast Asia, remains disputed. Two rival hypotheses, both assuming a demic component to the language dispersal, have been proposed. The first of these places the origin of Austroasiatic speakers in southeast Asia with a later dispersal to south Asia during the Neolithic, whereas the second hypothesis advocates pre-Neolithic origins and dispersal of this language family from south Asia. To test the two alternative models, this study combines the analysis of uniparentally inherited markers with 610,000 common single nucleotide polymorphism loci from the nuclear genome. Indian AA speakers have high frequencies of Y chromosome haplogroup O2a; our results show that this haplogroup has significantly higher diversity and coalescent time (17–28 thousand years ago) in southeast Asia, strongly supporting the first of the two hypotheses. Nevertheless, the results of principal component and “structure-like” analyses on autosomal loci also show that the population history of AA speakers in India is more complex, being characterized by two ancestral components—one represented in the pattern of Y chromosomal and EDAR results and the other by mitochondrial DNA diversity and genomic structure. We propose © The Author 2010. Published by Oxford University Press on behalf of the Society for Molecular Biology and Evolution. All rights reserved. * Corresponding author: tk331@cam.ac.uk. . Supplementary Material Supplementary figures S1 to S6 and supplementary tables S1 to S10 are available at Molecular Biology and Evolution online (http://www.mbe.oxfordjournals.org/). Chaubey et al. Page 2 that AA speakers in India today are derived from dispersal from southeast Asia, followed by extensive sex-specific admixture with local Indian populations. Keywords Austroasiatic; mtDNA; Y chromosome; autosomes; admixture Europe PMC Funders Author Manuscripts