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Title

Influence of Admixture and Paleolithic Range Contractions on Current European Diversity Gradients

Authors
Arenas, Miguel
François, Olivier
Published in Molecular Biology and Evolution. 2013, vol. 30, no. 1, p. 57-61
Abstract Cavalli-Sforza and Edwards (Analysis of human evolution. 1963. In: Geerts SJ, editor. Genetics today: Proceedings of the 11th International Congress of Genetics, The Hague, The Netherlands. New York: Pergamon. p. 923-993.) initiated the representation of genetic relationships among human populations with principal component (PC) analysis (PCA). Their study revealed the presence of a southeast-northwest (SE-NW) gradient of genetic variation in current European populations, which was interpreted as the result of the demic diffusion of early neolithic farmers during their expansion from the near east. However, this interpretation has been questioned, as PCA gradients can occur even when there is no expansion and because the first PC axis is often orthogonal to the expansion axis. Here, we revisit PCA patterns obtained under realistic scenarios of the settlement of Europe, focusing on the effects of various levels of admixture between paleolithic and neolithic populations, and of range contractions during the last glacial maximum (LGM). Using extensive simulations, we find that the first PC (PC1) gradients are orthogonal to the expansion axis, but only when the expansion is recent (neolithic). More ancient (paleolithic) expansions alter the orientation of the PC1 gradient due to a spatial homogenization of genetic diversity over time, and to the exact location of LGM refugia from which re-expansions proceeded. Overall we find that PC1 gradients consistently follow an SE-NW orientation if there is a large paleolithic contribution to the current European gene pool, and if the main refuge area during the last ice age was in the Iberian Peninsula. Our study suggests that an SE-NW PC1 gradient is compatible with little genetic impact of neolithic populations on the current European gene pool, and that range contractions have affected observed genetic patterns.
Keywords Range expansionRange contractionAdmixturePrincipal component analysisEuropean settlementLast glacial maximum
Identifiers
PMID: 22923464
Full text
Structures
Research groups TIGERS
Unité d'anthropologie
Envirospace Lab
Groupe Sanchez-Mazas
ISE Pôle Sciences
ISE Pôle Informatique environnementale
ISE Biodiversité
Groupe Currat
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ARENAS, Miguel et al. Influence of Admixture and Paleolithic Range Contractions on Current European Diversity Gradients. In: Molecular Biology and Evolution, 2013, vol. 30, n° 1, p. 57-61. https://archive-ouverte.unige.ch/unige:24758

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Deposited on : 2012-12-19

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