Mitochondrial DNA variation and language replacements in the Caucasus

Abstract

Sequences of the ¢rst hypervariable segment of the mitochondrial DNA (mtDNA) control region were obtained from 353 individuals representing nine groups and four major linguistic families (IndoEuropean, Altaic and North and South Caucasian) of the Caucasus region. The diversity within and between Caucasus populations exceeded the diversity within Europe, but was less than that in the Near East. Caucasus populations occupy an intermediate position between European and Near Eastern populations in tree and principal coordinate analyses, suggesting that they are either ancestral to European populations or derived via admixture from European and Near Eastern populations. The genetic relationships among Caucasus populations re£ect geographical rather than linguistic relationships. In particular, the Indo-European-speaking Armenians and Altaic-speaking Azerbaijanians are most closely related to their nearest geographical neighbours in the Caucasus, not their linguistic neighbours (i.e. other Indo-European or Altaic populations). The mtDNA evidence thus suggests that the Armenian and Azerbaijanian languages represent instances of language replacement that had little impact on the mtDNA gene pool.

High-throughput sequencing of complete human mtDNA genomes from the Caucasus and West Asia: high diversity and demographic inferences

“…The clustering of groups on the basis of geographic rather than linguistic relationships is in keeping with previous studies of genetic diversity among Caucasian populations. 10,11 However, the complete mtDNA genome sequences do reveal some additional genetic similarity between the two Turkic-speaking groups (Azeri and Turks) that was not evident in previous studies. Presumably, the sharing of some Central Asian mtDNA haplogroups by Azeri and Turks (Table 3) accounts for this signal of genetic similarity between the Azeri and the Turks.…”

“…mtDNA studies reveal a high level of diversity, exceeding that within all of Europe and only slightly lower than West Asian mtDNA diversity, which might indicate an old age of human populations from this region. 10 Overall, the Caucasus groups showed greater similarity with West Asian than with European groups for both genetic systems, although this similarity was much more pronounced for the Y chromosome than for mtDNA, suggesting that recent male-mediated migrations from West Asia have influenced the genetic structure of Caucasus populations. 11 Previous studies of complete mtDNA genome sequences have in general first obtained HV1 sequences (and sometimes, genotyped some haplogroup-defining SNPs), and then selected particular individuals of interest for complete mtDNA genome sequencing.…”

“…[6][7][8][9][10][11][12][13][14][15] These studies were mostly based on sequences of the first hypervariable segment of the noncoding mtDNA control region (HV1) and Y chromosome binary marker variation in various groups from this region. mtDNA studies reveal a high level of diversity, exceeding that within all of Europe and only slightly lower than West Asian mtDNA diversity, which might indicate an old age of human populations from this region.…”

Neolithic patrilineal signals indicate that the Armenian plateau was repopulated by agriculturalists

“…16,17 In the efforts to gain a comprehensive understanding of the impact that complex historical migrations and events have had upon the genetic structure of populations, the human Y-chromosome has emerged as a highly effective tool. 18 Prior examinations of the paternal lineages within Armenia have revealed population-expansion times corresponding to the Neolithic emergence of agriculture, 19 as well as genetic affinities toward both Near Eastern and European populations; 20,21 results that are largely corroborated by mitochondrial DNA 22 and Alu insertion (PAI) studies. 23 It should be noted, however, that the above-mentioned patrilineal studies are hindered by their utilization of a limited set of Y-chromosomal markers that severely restricted their ability to define phylogenetic relationships.…”

The key role of patrilineal inheritance in shaping the genetic variation of Dagestan highlanders

“…[9][10][11] Others suggest that the genetic legacy of the Caucasus region is mainly because of the people who crossed or invaded this territory in historic times. 12 A large amount of genetic data on the Caucasian populations, based on classical markers, 9,[13][14][15] Alu insertion polymorphisms, 10 mitochondrial DNA 10,16 and the non-recombining portion of the Y chromosome (NRY) 17 have shown that neither geography nor linguistics have had a strong influence on the genetic structure of these ethnic groups and that genetic drift appears to be the main factor acting in the region. Furthermore, Y chromosomes of highland Dagestan ethnic groups appear to have undergone genetic drift independently of the population history of mitochondrial and autosomal loci, suggesting that social rules, and not simply geographic isolation, are the causal agents for the high NRY diversity observed among highlanders.…”