Extensive recent secondary contacts between four European white oak species

Thibault Leroy (1) , Camille Roux (2) , Laure Villate (1) , Catherine Bodénès (1) , Jonathan Romiguier (2) , Jorge A. P. Paiva (3, 4) , Carole Dossat (5) , Jean-Marc Aury (5) , Christophe Plomion (1) , Antoine Kremer (1)

1 BioGeCo - Biodiversité, Gènes & Communautés
2 DEE - Department of Ecology and Evolution [UNIL, Lausanne] = Département d'écologie et évolution
3 IBET - Instituto de Biologia Experimental e Tecnológica
4 PAN - Polska Akademia Nauk = Polish Academy of Sciences = Académie polonaise des sciences
5 LBGB - Laboratoire de Bioinformatique pour la Génomique et la Biodiversité

*Historical trajectories of tree species during the late Quaternary have been well reconstructed through genetic and palaeobotanical studies. However, many congeneric tree species are interfertile, and the timing and contribution of introgression to species divergence during their evolutionary history remains largely unknown. *We quantified past and current gene flow events between four morphologically divergent oak species (Quercus petraea, Q. robur, Q. pyrenaica, Q. pubescens), by two independent inference methods: diffusion approximation to the joint frequency spectrum (∂a∂i) and approximate Bayesian computation (ABC). For each pair of species, alternative scenarios of speciation allowing gene flow over different timescales were evaluated. *Analyses of 3524 single nucleotide polymorphisms (SNPs) randomly distributed in the genome, showed that these species evolved in complete isolation for most of their history, but recently came into secondary contact, probably facilitated by the most recent period of postglacial warming. *We demonstrated that: there was sufficient genetic differentiation before secondary contact for the accumulation of barriers to gene flow; and current European white oak genomes are a mosaic of genes that have crossed species boundaries and genes impermeable to gene flow.

Mots clés: genetical analysis; paleobotany; bayesian method; forest tree; sessile oak; pedunculate oak

Mots clés: quaternaire; analyse génétique; paléobotanique; calcul bayésien; interfertilité; flux de gènes; arbre forestier; quercus petraea; quercus pyrenaica; quercus robur; quercus pubescens; polymorphisme nucléotidique simple (SNP); congènere

Domaines: Sciences du Vivant [q-bio]

Thibault Leroy, Camille Roux, Laure Villate, Catherine Bodénès, Jonathan Romiguier, et al.. Extensive recent secondary contacts between four European white oak species. New Phytologist, 2017, 214 (2), pp.865-878. ⟨10.1111/nph.14413⟩. ⟨hal-01608621⟩