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 m ay be predicted that there has been very little male gene flow across ethni c boundaries. To test this finding, we have analyzed DNA samples of individ uals 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 haplot ypes were constructed on the basis of one RFLP locus and five microsatellit e loci. The haplotype distribution among the groups showed that different e thnic groups harbor nearly disjoint sets of haplotypes. This indicates that there has been virtually no male gene flow among ethnic groups. Analysis o f molecular variance revealed that there was significant haplotypic variati on between castes and tribes, but nonsignificant variation among ranked cas te clusters. Haplotypic variation attributable to differences in geographic al regions of habitat was also nonsignificant.