April 22, 2010

Origin and dispersal of mtDNA haplogroup U5 (Malyarchuck et al. 2010)

From the conclusion:
Genetic data obtained in this study allows the suggestion that during the LGM period, central European territories probably represented the area of intermingling between human flow from refugial zones in the Balkans, the Mediterranean coastline and the Pyrenees, as U5a and U5b gene flows occurred from there. Based on dating analysis of the U5 subclusters, it seems very likely that, despite the archaeological evidence testifying to the presence of humans in eastern Europe during the Ice Age, this part of Eurasia might have only been re-populated by modern humans at the end of the LGM, i.e. later than central Europe. In addition, U5b gene flow from central to eastern Europe become much more intense after the LGM. In general, we believe that molecular genetic data, in addition to archaeological and fossil evidence, are of significant use for resolving key questions regarding the interaction of human communities and climate.
The presence of mtDNA U2 in Russia (Kostenki) 30 thousand years ago, and the discovery of plentiful U5 in pre-farming populations is consistent with the scenario proposed by the authors. Now, if we find a U5 type in eastern Europe of e.g., Kostenki-age, the authors' hypothesis will be rejected. But, so far, the late (but pre-farming) time frame proposed by the authors is consistent with all our ancient European mtDNA sample points.

The sequence of events, as they now appear, include the earliest appearance of U2 in the eastern European plain (and possibly U4), the later appearance of U5, and then the advent of farming via the Balkans and Central Europe which brought the full suite of present-day Caucasoid haplogroups into the region.

PLoS ONE doi:10.1371/journal.pone.0010285

The Peopling of Europe from the Mitochondrial Haplogroup U5 Perspective

Boris Malyarchuk et al.


It is generally accepted that the most ancient European mitochondrial haplogroup, U5, has evolved essentially in Europe. To resolve the phylogeny of this haplogroup, we completely sequenced 113 mitochondrial genomes (79 U5a and 34 U5b) of central and eastern Europeans (Czechs, Slovaks, Poles, Russians and Belorussians), and reconstructed a detailed phylogenetic tree, that incorporates previously published data. Molecular dating suggests that the coalescence time estimate for the U5 is ~25–30 thousand years (ky), and ~16–20 and ~20–24 ky for its subhaplogroups U5a and U5b, respectively. Phylogeographic analysis reveals that expansions of U5 subclusters started earlier in central and southern Europe, than in eastern Europe. In addition, during the Last Glacial Maximum central Europe (probably, the Carpathian Basin) apparently represented the area of intermingling between human flows from refugial zones in the Balkans, the Mediterranean coastline and the Pyrenees. Age estimations amounting for many U5 subclusters in eastern Europeans to ~15 ky ago and less are consistent with the view that during the Ice Age eastern Europe was an inhospitable place for modern humans.



Gioiello said...

"the Balkans, the Mediterranean coastline and the Pyrenees" don't mean "Greece", but perhaps the Italian Refugium during the Younger Dryas and all the maps we have of the Epigravettian. Two of these haplotypes are clearly born in Italy: U5b3 and U5a2.

Maju said...

Actually I could not find any kind of data from the Balcans and Ukraine in the paper and supplementary material (which I read yesterday but deemed not really too interesting after all). The region they call Mediterranean-West Europe is made up of Italy, Spain, France, Ireland, Tunisia and Morocco it seems.

Anyhow I was working a bit with the available data and seems to me that the full lineage might have originated in Central Europe (Middle Danube area) but the lack of data for many southern areas (also West Asia) makes this assessment a mere fancy exercise.

Some lineages would seem to have a more westerly or easterly distribution and the presence in Africa would suggest that U5b1b1 and U5b1d might have been in SW Europe already by Gravettian times, their cousin U5b1c seems very much Italian.

Other lineages instead seem more specific of Eastern Europe: U5b1a and many under U5a, which seems to have a more oriental distribution in general, with only limited presence in Africa.

Maju said...

Also I was kind of negatively surprised to find very little (near zero) info on U5b3 which is the only U5 sublineage that (according to PhyloTree) has a meaningful star-like structure and hence signaling a fast expansion, which could give us clues on the whole lineage. All I know is that this clade is found very specially in Sardinia but also seems to have at least Czech representatives as well (anyone with more data on this key but neglected subhaplogroup U5b3?)