Rare uniparental lineages reveal external ancestries in the gene pool of the Italian linguistic enclave of Grecìa Salentina

Can language be a valuable predictor of genetic diversity even at the level of extremely circumscribed areas of linguistic diversity? We report on the analysis of mtDNA and NRY variation extracted from the whole-genome sequencing of 27 natives of Grecìa Salentina, a geographic area in southern Italy home to a historic Greek-speaking community. With respect to mtDNA, we found similarities with samples from Central Italy and Eastern Balkan, mainly because of the high haplogroups N, K and J1 frequencies. Detailed phylogeographic analyses of these haplogroups reveal instances of Grecìa Salentina-specific lineages. With respect to the NRY, we find similarities with other samples from southern Italy, Anatolia and the Middle East, because of the overwhelming frequency of haplogroup J2a. The new J2a lineages, many of which are specific to Grecìa Salentina, greatly expand the phylogeny of the haplogroup. Haplogroup R1a is also overrepresented, with a new lineage belonging to the GML6 subclade, which is common in the Western Balkans. All the above haplogroups were long recognized as markers of post-Neolithic East-to-West movements through the Balkan Peninsula by land or off its coasts by sea. We conclude that the peculiar component detected in the Grecìa Salentina gene pool is the result of past immigration. Specifically, there was a demic contribution of both sexes, which foreshadows the build-up of an entire community, and subsequent dilution in the surrounding gene pool by admixture occurred only to a limited extent. These results add a genomic dimension to our knowledge of the identity of the Greek-speaking community settled in Grecìa Salentina. To date, the peculiarity of the Grecìa Salentina population was only its linguistic identity, but we now show that it is also supported by a genetic component. The more general hypothesis of a connection between the demic and linguistic structure of the area can now be tested by comparing the genetics of Grecìa Salentina to those of other linguistic enclaves of Balkan origin in southern Italy.