Genetic structure and affinities among tribal populations of southern India: a study of 24 autosomal DNA markers

Abstract

SummaryWe describe the genetic structure and affinities of five Dravidian-speaking tribal populations inhabiting the Nilgiri hills of Tamil Nadu, in south India, using 24 autosomal DNA markers. Our goals were: (i) to examine what evolutionary forces have most significantly impacted south Indian tribal genetic variation, and (ii) to test whether the phenotypic similarities of some south Indian tribal groups to Africans represent a signature of close relationship to Africans or are due to convergence. All loci were polymorphic and average heterozygosities were substantial (range: 0.347-0.423). Genetic differentiation was high (G st = 6.7%) and genetic distances were not significantly correlated with geographic distances. Genetic drift therefore probably played a significant role in shaping the patterns of genetic variation observed in southern Indian tribal populations. Otherwise, analyses of population relationships showed that Indian populations are closely related to one another, regardless of phenotypic characteristics, and do not show particular affinities to Africans. We conclude that the phenotypic similarities of some Indian groups to Africans do not reflect a close relationship between these groups, but are better explained by convergence.

A Genomic Insight into Diversity Among Tribal and Nontribal Population Groups of Manipur, India

“…This diversity of mongoloid groups is evident in the present populations. Gene differentiation (Gst) is very high (9.8%) for the four populations compared with other Indian population groups studied, such as the Nilgiri hill tribes (6.8%; Vishwanathan et al 2004) and Andhra Pradesh populations (4.2%; Saraswathy et al 2008). Chakrabarti et al (2002) reported a Gst value as high as 9.9% where the populations selected were not only from diverse groups (Mizo, Rana Tharu, Katharia Tharu, Ho, and Toto) but also had different geographic (West Bengal and Himalayan regions) and linguistic affiliations (Tibeto-Burman and Indo-European).…”

Fine-scaled human genetic structure revealed by SNP microarrays

“…Our analyses also shed additional light on the genetic structure of Indian populations, which has been the subject of much research and debate (Bamshad et al 1998(Bamshad et al , 2001Basu et al 2003;Vishwanathan et al 2004;Watkins et al 2005Watkins et al , 2008Rosenberg et al 2006;Chaubey et al 2007). Our results show relatively larger genetic distances between the caste and tribal populations than among caste populations (Fig.…”

“…The origins of and relationships among Indian populations are the subjects of continuing debate (Bamshad et al 1998(Bamshad et al , 2001Basu et al 2003;Vishwanathan et al 2004;Watkins et al 2005;Rosenberg et al 2006;Chaubey et al 2007), but most previous genetic studies of these populations have been based on modest data sets. Indian populations are also used increasingly in linkage and case-control studies of genetic disease (Alcais et al 2007;Chambers et al 2008;Holliday et al 2008).…”

Association of ACE <i>DD</i> Genotype with Hypertension among the Tribal Populations of South India

“…The South Indian tribal communities represent a primitive, negroid, proto-australoid population ancestry, which are characterized by their unique cultural practices and endogamy [17][18][19][20][21].…”