Maternal genetic link of a south Dravidian tribe with native Iranians indicating bidirectional migration

A comprehensive review of HVS-I mitochondrial DNA variation of 19 Iranian populations

Iran is located along the Central Asian corridor, a natural artery that has served as a cross-continental route since the first anatomically modern human populations migrated out of Africa. We compiled and reanalyzed the HVS-I (hypervariable segment-I) of 3840 mitochondrial DNA (mtDNA) sequences from 19 Iranian populations and from 26 groups from adjacent countries to give a comprehensive review of the maternal genetic variation and investigate the impact of historical events and cultural factors on the maternal genetic structure of modern Iranians. We conclude that Iranians have a high level of genetic diversity. Thirty-six haplogroups were observed in Iran's populations, and most of them belong to widespread West-Eurasian haplogroups, such as H, HV, J, N, T, and U. In contrast, the predominant haplogroups observed in most of the adjacent countries studied here are H, M, D, R, U, and C haplogroups. Using principal component analysis, clustering, and genetic distance-based calculations, we estimated moderate genetic relationships between Iranian and other Eurasian groups. Further, analyses of molecular variance and comparing geographic and genetic structures indicate that mtDNA HVS-I sequence diversity does not exhibit any sharp geographic structure in the country. Barring a few from some culturally distinct and naturally separated minorities, most Iranian populations have a homogenous maternal genetic structure.

The maternal U1 haplogroup in the Koraga tribe as a correlate of their North Dravidian linguistic affinity

Introduction: The Koraga tribe are an isolated endogamous tribal group found in the southwest coastal region of India. The Koraga language shares inherited grammatical features with North Dravidian languages. To seek a possible genetic basis for this exceptionality and understand the maternal lineage pattern, we have aimed to reconstruct the inter-population and intra-population relationships of the Koraga tribal population by using mtDNA markers for the hypervariable regions along with a partial coding region sequence analysis. Methods and Results: Amongst the 96 individuals studied, we observe 11 haplogroups, of which a few are shared and others are unique to the clans Soppu, Oṇṭi and Kuṇṭu. In addition to several deep rooted Indian-specific lineages of macrohaplogroups M and U, we observe a high frequency of the U1 lineage (∼38%), unique to the Koraga. A Bayesian analysis of the U1 clade shows that the Koraga tribe share their maternal lineage with ancestral populations of the Caucasus at the cusp of the Last Glacial Maximum. Discussion: Our study suggests that the U1 lineage found in the Indian subcontinent represents a remnant of a post-glacial dispersal. The presence of West Asian U1 when viewed along with historical linguistics leads us to hypothesise that Koraga represents a mother tongue retained by a vanquished population group that fled southward at the demise of the Indus civilisation as opposed to a father tongue, associated with a particular paternal lineage.

The maternal ancestry of the Kavaratti islanders and the last glacial maximum aftermath

The prehistoric human settlement of the Lakshadweep islands remains a mystery for various reasons. Uncertainty about the existence of indigenous tribes in these islands and the lack of folklore records present major obstacles to the reconstruction of Lakshadweep ancestry. However, with extant population data, we seek to understand the maternal ancestry of the Kavaratti islanders. Mitochondrial control region variation analysis of 80 individuals from this island shows maternal links with the populations in the northwestern region of the South Asian mainland. The founder clade R30b2, observed in the Kavaratti islanders, is so far present only in the Scheduled Castes from the Punjab region, Jat Sikhs and Nairs. All other mainland populations carry basal R30 or R30a subclades. The presence of a specific Uralic U4 lineage in our samples, in addition to the Indo-European affinity observed in the phylogeny tree, substantiates a northwestern maternal ancestry of the Kavaratti islanders and implies an ancestral admixture with early humans in the Near East at the time of the last glacial maximum (LGM). Based on our Bayesian analysis, we furthermore propose that a group bearing mostly R30b2 during the LGM recovery, moved eastward and southward, where they received Indian-specific M haplogroups. Hence, the maternal ancestry of the Kavaratti islanders is evidently a consequence of the demographic changes in the northwestern region of the Indian subcontinent caused by the Last Glacial Maximum. The haplogroup distribution pattern and nucleotide sequence data produced in this study will enrich the forensic database of the Lakshadweep islands.

Mitochondrial DNA (CA)n dinucleotide repeat variations in Sinhalese and Vedda populations in Sri Lanka

Sinhalese and Vedda people are respectively the major ethnic group and the descendants of the probably earliest inhabitants of Sri Lanka, both believed to have a long history of settlement on the island. However, very little information is available on the origin and possible migration patterns of the two populations. Some studies have focused on (CA) dinucleotide repeat variations located in the mitochondrial hypervariable region 3 (HVS3) (base pairs 514-524) as a useful biomarker to understand migration patterns of different populations. Hence, here we analyze these repeat variations in these two ethnic groups to understand their historical roots and possible patterns of gene flow. Blood samples were collected from healthy, maternally unrelated individuals (N = 109) and mitochondrial D-loop was amplified and sequenced. The (CA)₄ dinucleotide repeat in hypervariable region 3 was detected in the majority of Vedda samples while the remaining samples were defined by a (CA)₅ cluster. In contrast, the (CA)₅ repeat was the most frequent among Sinhalese followed by (CA)₄ and (CA)₇ repeats. Haplogroup diversity of (CA)₄ variation indicated that the majority of Sinhalese individuals grouped into the M30 haplogroup while Vedda clustered into the R5a2b and U7a2 haplogroups. No significant differences in diversity measures were observed among the two populations. However, Multidimensional Scaling indicated a separate clustering for aboriginal Vedda and contemporary Sinhalese populations. Results from this study can be used together with mitochondrial DNA information from hypervariable regions 1 and 2 to perform anthropological and forensic investigations in the two populations studied.