Genetic differentiation between upland and lowland populations shapes the Y-chromosomal landscape of West Asia.

Y-chromosomal variation in West Asian populations has so far been studied in less detail than in the neighboring Europe. Here, we analyzed 598 Y-chromosomes from two West Asian subregions-Transcaucasia and the Armenian plateau-using 40 Y-SNPs and 17 Y-STRs and combined them with previously published data from the region. The West Asian populations fell into two clusters: upland populations from the Anatolian, Armenian and Iranian plateaus, and lowland populations from the Levant, Mesopotamia and the Arabian Peninsula. This geographic subdivision corresponds with the linguistic difference between Indo-European and Turkic speakers, on the one hand, and Semitic speakers, on the other. This subdivision could be traced back to the Neolithic epoch, when upland populations from the Anatolian and Iranian plateaus carried similar haplogroup spectra but did not overlap with lowland populations from the Levant. We also found that the initial gene pool of the Armenian motherland population has been well preserved in most groups of the Armenian Diaspora. In view of the contribution of West Asians to the autosomal gene pool of the steppe Yamnaya archaeological culture, we sequenced a large portion of the Y-chromosome in haplogroup R1b samples from present-day East European steppe populations. The ancient Yamnaya samples are located on the "eastern" R-GG400 branch of haplogroup R1b-L23, showing that the paternal descendants of the Yamnaya still live in the Pontic steppe and that the ancient Yamnaya population was not an important source of paternal lineages in present-day West Europeans.

Assessment of patrilineal gene pool of the Iranian Azeris.

The Iranian Azeris are the largest ethno-linguistic minority in Iran who live mainly in the north-west part of the country. Located in the crossroad of ancient human migrations the Iranian Azeris bear the complicated historical influence of the region in their gene pool. Despite the importance of Iranian Azeris in reconstructing the historical event of the Middle-East, their (genetic) origin still remains heavily disputed. In this study we tried to evaluate the rates of genetic contribution of possible source populations (namely, indigenous Iranian, Caucasian, and Central Asian) in the gene pool of modern Iranian Azeris through paternally inherited Y-chromosomal 6 STR markers. The assessment of genetic distances reveals that the Iranian Azeris are mixed population with substantial North Caucasian genetic contribution being genetically much closer to their immediate neighboring ethnic groups. Based on the results of admixture analysis we can conclude that there are significant Caucasian and no visible Central Asian contribution to the gene pool of modern Iranian Azeris.

Patrilocality and recent migrations have little impact on shaping patterns of genetic structure of the Armenian population.

In general, genetic distances between human populations (also within one ethnic group) are larger for the Y chromosome markers than for the mtDNA. It is usually explained by higher rate of female versus male migration due to the cultural practice of patrilocality, when women move to their husbands' residence after marriage. Recently found a reversed picture for the genetic variation in some ethno-territorial groups confirm the strict role of cultural traditions in shaping patterns of populations' genetic structure. To test the role of patrilocality for the genetic structure of the Armenian population, we compared the Y chromosome and the mtDNA haplotype variations among and between geographical groups identified according to paternal (maternal) grandparental place of birth, from one side, and the populations currently living in the same geographical areas, from the other side. The results demonstrate that the Armenian population is regionally more structured for the Y chromosome than for the mtDNA. Additionally, in spite of expressed directivity of migration processes (caused by the phenomenon of patrilocality as well), the patterns of genetic variations for the populations of the same geographic areas remain without any significant changes during the last three generations.

Iranian Azeri's Y-Chromosomal Diversity in the Context of Turkish-Speaking Populations of the Middle East.

BACKGROUND: The main goal of this study was to conduct a comparative population genetic study of Turkish speaking Iranian Azeries as being the biggest ethno-linguistic community, based on the polymorph markers on Y chromosome. METHODS: One hundred Turkish-speaking Azeri males from north-west Iran (Tabriz, 2008-2009) were selected based on living 3 generations paternally in the same region and not having any relationship with each other. Samples were collected by mouth swabs, DNA extracted and multiplex PCR done, then 12 Single Nucleotide Polymorphisms (SNPs) and 6 Microsatellites (MS) were sequenced. Obtained data were statistically analyzed by Arlequin software. RESULTS: SNPs and Microsatellites typing were compared with neighboring Turkish-speaking populations (from Turkey and Azerbaijan) and Turkmens representing a possible source group who imposed the Turkish language during 11-15(th) centuries AD. Azeris demonstrated high level of gene diversity compatible with patterns registered in the neighboring Turkish-speaking populations, whereas the Turkmens displayed significantly lower level of genetic variation. This rate of genetic affiliation depends primarily on the geographic proximity. CONCLUSION: The imposition of Turkish language to this region was realized predominantly by the process of elite dominance, i.e. by the limited number of invaders who left only weak patrilineal genetic trace in modern populations of the region.

Armenian Y chromosome haplotypes reveal strong regional structure within a single ethno-national group.

Armenia has been little-studied genetically, even though it is situated in an important area with respect to theories of ancient Middle Eastern population expansion and the spread of Indo-European languages. We screened 734 Armenian males for 11 biallelic and 6 microsatellite Y chromosome markers, segregated them according to paternal grandparental region of birth within or close to Armenia, and compared them with data from other population samples. We found significant regional stratification, on a level greater than that found in some comparisons between different ethno-national identities. A diasporan Armenian sub-sample (collected in London) was not sufficient to describe this stratified haplotype distribution adequately, warning against the use of such samples as surrogates for the non-diasporan population in future studies. The haplotype distribution and pattern of genetic distances suggest a high degree of genetic isolation in the mountainous southern and eastern regions, while in the northern, central and western regions there has been greater admixture with populations from neighbouring Middle Eastern countries. Georgia, to the north of Armenia, also appears genetically more distinct, suggesting that in the past Trans-Caucasia may have acted as a genetic barrier. A Bayesian full-likelihood analysis of the Armenian sample yields a mean estimate for the start of population growth of 4.8 thousand years ago (95% credible interval: 2.0-11.1), consistent with the onset of Neolithic farming. The more isolated southern and eastern regions have high frequencies of a microsatellite defined cluster within haplogroup 1 that is centred on a modal haplotype one step removed from the Atlantic Modal Haplotype, the centre of a cluster found at high frequencies in England, Friesland and Atlantic populations, and which may represent a remnant paternal signal of a Paleolithic migration event.