Erwan Pennarun „Meandering along the mtDNA phylogeny; causerie and digression about what it can tell us about human migrations”

On 7 October at 14:15 Erwan Pennarun will defend his doctoral thesis „Meandering along the mtDNA phylogeny; causerie and digression about what it can tell us about human migrations”.

Supervisor:
Professor Richard Villems, Institute of Molecular and Cell Biology
Senior Research Fellow of Modern Population Genetics, Mait Metspalu, Institute of Genomics

Oponent:
Associate Professor Rosa Fregel, PhD, Department of Genetics, University of La Laguna Ülikool, Tenerife, Spain

Summary:
Inscribed in our genomes, there is all the necessary information for the cellular machinery to build a human being. And then some. Using an ad hoc framework, it is possible to attempt to infer past human migrations by looking at the current variation present in these genomes. Mitochondrial DNA (mtDNA) and the Y chromosome have long been the poster child for doing it, chiefly thanks to their haploid and non-recombining nature, allowing to reconstruct their phylogeny in a more straightforward way than for the autosomes. These phylogenies have been shaped by evolutionary forces, amongst them migrations. Hence, by studying the former, it is theoretically possible to tackle questions germane to the latter.

One way to address our questions is to study the general composition of a specific population or several, and to place it into a broader perspective. For instance, we showed that, whilst the overall proportion of Eurasian and African specific lineages is almost identical in Ethiopian and Yemeni mtDNA gene pool, a finer level of resolution revealed marked differences in them. In the case of France, it is globally not dissimilar from its close neighbours, yet narrowing down the geographical focus exposes dissimilarities between the Basques living north of the Pyrénées from those south of them. And amongst the administrative departments of Brittany, Finistère displays tighter connections with Britain and Scandinavia. Much further east, in Central Asia, exploring various ethnic populations of the Afghan Hindu Kush gave support to the notion that Central Asia has been a long-standing cross-road of multiple waves of migrations, each leaving perceptible traces in the extant populations. As for another way of answering questions, we shifted our focus to some specific haplogroups, with a new examination of M1 and U6 phylogenies that confuted the previously purported concomitance of their spread. We also did not find strong evidence of connections between their spread and that of the Afro-Asiatic languages.