Thursday, 7 March 2013

Y chromosomes of Bulgarians (Karachanak et al. 2013)

Bulgaria had been something of a blank area in studies of uniparental markers, so it's nice to finally see a comprehensive Y-chromosome study of the country.
The dates in the paper are based on the "evolutionary mutation rate". I suspect that ancient DNA will be the final arbiter in this issue, because, for example, a Mesolithic TMRCA of E-V13 in Bulgaria implies that we'll find a lot of it in Neolithic contexts, whereas a Bronze Age one implies that we'll find a little if any of it, and a discontinuity across time.
Of interest is the occurrence of some E*(xM35, M2) in this sample in Burgas, Varna, and Plovdiv. It would be interesting to trace the ancestry of the bearers of these Y-chromosomes. I know that there still exists a minority-within-a-minority of Black Muslims in Greek Thrace, and it's not inconceivable that these Y-chromosomes may represent the legacy of a similar population; in any case, their haplotypes can be found in Table S5 for anyone wanting to investigate.
SNP Diversity within R seems substantial, and as always, it is difficult to say much, since this may be a consequence of either (i) a plausible role of the Balkans as a staging point of the likely invasion of Europe in late prehistory, or (ii) back-migration of derived R-bearers into the Balkans, be them Slavs or Goths or "eastern" folks of various stripes during history. Once again, I suspect that ancient DNA might solve this riddle, or, alternatively, routine high-coverage sequencing of the Y chromosome that might inform us, e.g., about the TMRCA of a Bulgarian and a German R-U152 or a Bulgarian and Polish R-M458.
PLoS ONE 8(3): e56779. doi:10.1371/journal.pone.0056779
Y-Chromosome Diversity in Modern Bulgarians: New Clues about Their Ancestry
Sena Karachanak et al

To better define the structure and origin of the Bulgarian paternal gene pool, we have examined the Y-chromosome variation in 808 Bulgarian males. The analysis was performed by high-resolution genotyping of biallelic markers and by analyzing the STR variation within the most informative haplogroups. We found that the Y-chromosome gene pool in modern Bulgarians is primarily represented by Western Eurasian haplogroups with ~ 40% belonging to haplogroups E-V13 and I-M423, and 20% to R-M17. Haplogroups common in the Middle East (J and G) and in South Western Asia (R-L23*) occur at frequencies of 19% and 5%, respectively. Haplogroups C, N and Q, distinctive for Altaic and Central Asian Turkic-speaking populations, occur at the negligible frequency of only 1.5%. Principal Component analyses group Bulgarians with European populations, apart from Central Asian Turkic-speaking groups and South Western Asia populations. Within the country, the genetic variation is structured in Western, Central and Eastern Bulgaria indicating that the Balkan Mountains have been permeable to human movements. The lineage analysis provided the following interesting results: (i) R-L23* is present in Eastern Bulgaria since the post glacial period; (ii) haplogroup E-V13 has a Mesolithic age in Bulgaria from where it expanded after the arrival of farming; (iii) haplogroup J-M241 probably reflects the Neolithic westward expansion of farmers from the earliest sites along the Black Sea. On the whole, in light of the most recent historical studies, which indicate a substantial proto-Bulgarian input to the contemporary Bulgarian people, our data suggest that a common paternal ancestry between the proto-Bulgarians and the Altaic and Central Asian Turkic-speaking populations either did not exist or was negligible.

No comments:

Post a Comment