Human Y-chromosome variation in the Western Mediterranean area: Implications for the peopling of the region

Y-chromosome variation was analyzed in a sample of 1127 mates from the West ern Mediterranean area by surveying 16 biallelic and 4 multiallelic sites. Some populations from Northeastern Europe and the Middle East were also stu died for comparison. All Y-chromosome haplotypes were included in a parsimo nious genealogic tree consisting of 17 haplogroups, several of which displa yed distinct geographic specificities. One of the haplogroups, HG9.2, has s ome features that are compatible with a spread into Europe from the Near Ea st during the Neolithic period. However, the current distribution of this h aplogroup would suggest that the Neolithic gene pool had a major impact in the eastern and central part of the Mediterranean basin, but very limited c onsequences in Iberia and Northwestern Europe. Two other haplogroups, HG25. 2 and HG2.2, were found to have much more restricted geographic distributio ns. The first most likely originated in the Berbers within the last few tho usand years, and allows the detection of gene flow to Iberia and Southern E urope. The latter haplogroup is common only in Sardinia, which confirms the genetic peculiarity and isolation of the Sardinians. Overall, this study d emonstrates that the dissection of Y-chromosome variation into haplogroups with a more restricted geographic distribution can reveal important differe nces even between populations that live at short distances, and provides ne w clues to their past interactions. Human Immunology 62, 871-884 (2001). (C ) American Society for Histocompatibility and Immunogenetics, 2001. Publish ed by Elsevier Science Inc.