title: Most of the extant mtDNA boundaries in south and southwest Asia were likely shaped during the initial settlement of Eurasia by anatomically modern humans.
abstract: BACKGROUND
  Recent advances in the understanding of the maternal and paternal heritage of south and southwest Asian populations have highlighted their role in the colonization of Eurasia by anatomically modern humans. Further understanding requires a deeper insight into the topology of the branches of the Indian mtDNA phylogenetic tree, which should be contextualized within the phylogeography of the neighboring regional mtDNA variation. Accordingly, we have analyzed mtDNA control and coding region variation in 796 Indian (including both tribal and caste populations from different parts of India) and 436 Iranian mtDNAs. The results were integrated and analyzed together with published data from South, Southeast Asia and West Eurasia.
  
  
  RESULTS
  Four new Indian-specific haplogroup M sub-clades were defined. These, in combination with two previously described haplogroups, encompass approximately one third of the haplogroup M mtDNAs in India. Their phylogeography and spread among different linguistic phyla and social strata was investigated in detail. Furthermore, the analysis of the Iranian mtDNA pool revealed patterns of limited reciprocal gene flow between Iran and the Indian sub-continent and allowed the identification of different assemblies of shared mtDNA sub-clades.
  
  
  CONCLUSIONS
  Since the initial peopling of South and West Asia by anatomically modern humans, when this region may well have provided the initial settlers who colonized much of the rest of Eurasia, the gene flow in and out of India of the maternally transmitted mtDNA has been surprisingly limited. Specifically, our analysis of the mtDNA haplogroups, which are shared between Indian and Iranian populations and exhibit coalescence ages corresponding to around the early Upper Paleolithic, indicates that they are present in India largely as Indian-specific sub-lineages. In contrast, other ancient Indian-specific variants of M and R are very rare outside the sub-continent.
authors.affiliation: Institute of Molecular and Cell Biology, Tartu University, Tartu, Estonia. mait@ebc.ee
authors.forename: Mait
authors.initials: M
authors.lastname: Metspalu
authors.forename: Toomas
authors.initials: T
authors.lastname: Kivisild
authors.forename: Ene
authors.initials: E
authors.lastname: Metspalu
authors.forename: Jüri
authors.initials: J
authors.lastname: Parik
authors.forename: Georgi
authors.initials: G
authors.lastname: Hudjashov
authors.forename: Katrin
authors.initials: K
authors.lastname: Kaldma
authors.forename: Piia
authors.initials: P
authors.lastname: Serk
authors.forename: Monika
authors.initials: M
authors.lastname: Karmin
authors.forename: Doron M
authors.initials: DM
authors.lastname: Behar
authors.forename: M Thomas P
authors.initials: MT
authors.lastname: Gilbert
authors.forename: Phillip
authors.initials: P
authors.lastname: Endicott
authors.forename: Sarabjit
authors.initials: S
authors.lastname: Mastana
authors.forename: Surinder S
authors.initials: SS
authors.lastname: Papiha
authors.forename: Karl
authors.initials: K
authors.lastname: Skorecki
authors.forename: Antonio
authors.initials: A
authors.lastname: Torroni
authors.forename: Richard
authors.initials: R
authors.lastname: Villems
mesh_terms: D001208:Asia; D001211:Asia, Western; D004272:DNA, Mitochondrial / Q000235:genetics*; D004641:Emigration and Immigration; D005006:Ethnicity / Q000235:genetics; D019143:Evolution, Molecular; D005828:Genetics, Population / Q000379:methods; D006239:Haplotypes / Q000235:genetics; D006801:Humans; D007194:India; D007492:Iran
chemical_list: D004272:DNA, Mitochondrial