Genetic population structure across Brittany and the downstream Loire basin provides new insights on the demographic history of Western Europe - Université de Bretagne Occidentale Access content directly
Special Issue Year : 2022

Genetic population structure across Brittany and the downstream Loire basin provides new insights on the demographic history of Western Europe

Michael Blum
  • Function : Author
Aude Saint Pierre
  • Function : Author
Emma Svensson
  • Function : Author
Charlotte Berthellier
  • Function : Author
Christine Fruchet
  • Function : Author
Elisabeth Quellery
  • Function : Author
Fernando Racimo
  • Function : Author
Jade Violleau
  • Function : Author
Eske Willerslev
  • Function : Author
Mael Jézéquel
  • Function : Author
Daniel Le-Bris
  • Function : Author
Clément Nicolas
  • Function : Author
Marcel Goldberg
  • Function : Author
Marie Zins
  • Function : Author
Hervé Le-Marec
  • Function : Author
Mattias Jakobsson
  • Function : Author
Pierre Darlu
  • Function : Author
  • PersonId : 1103099
  • IdRef : 032654952
Jean-François Deleuze
  • Function : Author
Richard Redon
  • Function : Author
Christian Dina
  • Function : Author

Abstract

European genetic ancestry originates from three main ancestral populations - Western hunter-gatherers, early European farmers and Yamnaya Eurasian herders - whose edges geographically met in present-day France. Despite its central role to our understanding of how the ancestral populations interacted and gave rise to modern population structure, the population history of France has remained largely understudied. Here, we analysed 856 high-coverage whole-genome sequences along with genome-wide genotyping data of 3,234 present-day individuals from the northern half of France and merged them with publicly available present-day and ancient Europe-wide genotype datasets. We also analysed, for the first time, the whole-genome sequences of six medieval individuals (300-1100 CE) from Western France to gain insights into the genetic impact of what is commonly known as the Migration Period in Europe. We found extensive fine-scale population structure across Brittany and the downstream Loire basin, emphasizing the need for investigating local populations to better understand the distribution of rare and putatively deleterious variants across space. Overall, we observed an increased population differentiation between the northern and southern sides of the river Loire, which are characterised by different proportions of steppe vs. Neolithic-related ancestry. Samples from Western Brittany carry the largest levels of steppe ancestry and show high levels of allele sharing with individuals associated with the Bell Beaker complex, levels that are only comparable with those found in populations lying on the northwestern edges of Europe. Together, our results imply that present-day individuals from Western Brittany retain substantial legacy of the genetic changes that occurred in Northwestern Europe following the arrival of the Bell Beaker people c. 2500 BCE. Such genetic legacy may explain the sharing of disease-related alleles with other present-day populations from Western Britain and Ireland.

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hal-04045175 , version 1 (24-03-2023)

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Isabel Alves, Joanna Giemza, Michael Blum, Carolina Bernhardsson, Stéphanie Chatel, et al.. Genetic population structure across Brittany and the downstream Loire basin provides new insights on the demographic history of Western Europe. 2022, ⟨10.1101/2022.02.03.478491⟩. ⟨hal-04045175⟩
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