High-resolution mtDNA evidence for the late-glacial resettlement of Europe from an Iberian refugium

Abstract

The advent of complete mitochondrial DNA (mtDNA) sequence data has ushered in a new phase of human evolutionary studies. Even quite limited volumes of complete mtDNA sequence data can now be used to identify the critical polymorphisms that define sub-clades within an mtDNA haplogroup, providing a springboard for large-scale high-resolution screening of human mtDNAs. This strategy has in the past been applied to mtDNA haplogroup V, which represents <5% of European mtDNAs. Here we adopted a similar approach to haplogroup H, by far the most common European haplogroup, which at lower resolution displayed a rather uninformative frequency distribution within Europe. Using polymorphism information derived from the growing complete mtDNA sequence database, we sequenced 1580 base pairs of targeted coding-region segments of the mtDNA genome in 649 individuals harboring mtDNA haplogroup H from populations throughout Europe, the Caucasus, and the Near East. The enhanced genealogical resolution clearly shows that sub-clades of haplogroup H have highly distinctive geographical distributions. The patterns of frequency and diversity suggest that haplogroup H entered Europe from the Near East ∼20,000–25,000 years ago, around the time of the Last Glacial Maximum (LGM), and some sub-clades re-expanded from an Iberian refugium when the glaciers retreated ∼15,000 years ago. This shows that a large fraction of the maternal ancestry of modern Europeans traces back to the expansion of hunter-gatherer populations at the end of the last Ice Age.

Using mitochondrial DNA to test the hypothesis of a European post-glacial human recolonization from the Franco-Cantabrian refuge

“…Although a mtDNA analysis in ancient Basque populations questioned that interpretation (Izagirre and de la Rua, 1999), the posterior molecular dissection of mtDNA haplogroup H, the dominant lineage in Europe, identified two subhaplogroups (namely H1 and H3) that displayed frequency distributions and coalescence ages very similar to those previously reported for haplogroup V (Achilli et al, 2004). As these patterns were confirmed by several independent studies (Loogvali et al, 2004;Pereira et al, 2005;Alvarez-Iglesias et al, 2009), this human refuge theory to explain the post-glacial resettlement of Europe has gained almost unanimous support. However, in our opinion, the issue is not yet satisfactorily settled.…”

Linking the sub-Saharan and West Eurasian gene pools: maternal and paternal heritage of the Tuareg nomads from the African Sahel

“…A major proportion (94%) could be allocated to haplogroups H1, H3 and V, West Eurasian lineages of Iberian origin that spread to Europe 7,10,17,26,29,36 and most probably North Africa 30,31 with the improvement of the climatic conditions after the retreat of the ice sheets 15 000-13 000 years ago. Both H1 and H3 commonly display rather low diversity in the D-loop region, but the Tuareg haplotypes belonging to haplogroup V have a specific diagnostic mutation -the transition at position 16 234.…”

“…The geographic location used is the centre of the distribution area, from where the individual samples of each population were collected. Comparative data for H1 and H3 were taken from Finnila et al, 27 Herrnstadt et al, 28 Pereira et al, 29 Cherni et al 30 and Ennafaa et al; 31 and those for haplogroup V from Torroni et al, 10 Pereira et al, 32 Behar et al 33 and Cherni et al 30 …”

Ancient mitochondrial lineages support the prehistoric maternal root of Basques in Northern Iberian Peninsula

“…5,6 Based on genetic data of current populations, the Franco-Cantabrian region (south-western Europe) appears as a keystone in the post-glacial settlement of the European continent. 1,[7][8][9] Even though human remains of pre-Neolithic period are very scarce, archaeological data from this region, such as abundant cultural records of Palaeolithic hunter-gatherer human groups living during the Last Glacial Maximum, suggest that this was the most densely populated European region along the Upper Palaeolithic. 10 The Cave of Santimamiñe is located at the oriental side of the Oka river basin and very close to its estuary, o10 km from the current shore of Cantabrian sea, within the area of settlement of the FrancoCantabrian refuge ( Figure 1).…”