Negligible Male Gene Flow Across Ethnic Boundaries in India, Revealed by Analysis of Y-Chromosomal DNA Polymorphisms

From the historically prevalent social structure of Indian populations it may be predicted that there has been very little male gene flow across ethnic boundaries. To test this finding, we have analyzed DNA samples of individuals belonging to 10 ethnic groups, speaking Indo-European or Austroasiatic languages and inhabiting the eastern and northern regions of India. Eight Y-chromosomal markers, two biallelic and six microsatellite, were studied. All populations were monomorphic for the deletion allele at the YAP (DYS287) locus and for the 119-bp allele at the DYS288 locus. Y-chromosomal haplotypes were constructed on the basis of one RFLP locus and five microsatellite loci. The haplotype distribution among the groups showed that different ethnic groups harbor nearly disjoint sets of haplotypes. This indicates that there has been virtually no male gene flow among ethnic groups. Analysis of molecular variance revealed that there was significant haplotypic variation between castes and tribes, but nonsignificant variation among ranked caste clusters. Haplotypic variation attributable to differences in geographical regions of habitat was also nonsignificant.