Relaxed Selection During a Recent Human Expansion

Genetics February 1, 2018 vol. 208 no. 2 763-777

Stephan Peischl, Isabelle Dupanloup, Adrien Foucal, Michèle Jomphe, Vanessa Bruat, Jean-Christophe Grenier, Alexandre Gouy, Kimberly J. Gilbert, Elias Gbeha, Lars Bosshard, Elodie Hip-Ki, Mawussé Agbessi, Alan Hodgkinson, Hélène Vézina, Philip Awadalla, Laurent Excoffier

Abstract

Humans have colonized the planet through a series of range expansions, which deeply impacted genetic diversity in newly settled areas and potentially increased the frequency of deleterious mutations on expanding wave fronts. To test this prediction, the authors of this study, including Isabelle Dupanloup Duperret, analyzed the genomic diversity of French Canadians who colonized Quebec in the 17th century. They found significant differences between individuals whose ancestors lived mostly on the colonizing wave front and individuals whose ancestors remained in the core of the settlement. Even though range expansions have had a relatively limited impact on the overall fitness of French Canadians, they could explain the higher prevalence of recessive genetic diseases in recently settled regions of Quebec.