Relaxed Selection During a Recent Human Expansion

• DOI: 10.1534/genetics.117.300551
• Publication Date: 2017-11-29T15:45:39Z
• Authors: Stephan Peischl; Isabelle Dupanloup; Adrien Foucal; Michèle Jomphe; Vanessa Bruat; Jean-Christophe G...; Alexandre Gouy; K J Gilbert; Elias Gbeha; Lars Bosshard; Elodie Hip-Ki; Mawussé Agbessi; Alan Hodgkinson; Hélène Vézina; Philip Awadalla; Laurent Excoffier
• Keywords: Founder effect; Genetic drift

Humans have colonized the planet through a series of range expansions, which deeply impacted genetic diversity in newly settled areas and potentially increased frequency deleterious mutations on expanding wave fronts. To test this prediction, we studied genomic French Canadians who Quebec 17th century. We used historical information records from ∼4000 ascending genealogies to select individuals whose ancestors lived mostly colonizing front remained core settlement. Comparison exomic reveals that: (i) both new low-frequency variants are significantly more than individuals, (ii) equally at higher frequencies (iii) two times likely be homozygous for rare very present Europeans. These differences emerged past six nine generations cannot explained by differential inbreeding, but consistent with relaxed selection mainly due rates drift front. Demographic inference modeling evolution suggest lower effective size front, lead an estimation coefficients that increase conservation scores. Even though expansions had relatively limited impact overall fitness Canadians, they could explain prevalence recessive diseases recently regions Quebec.