title: Demographic history of the trace metal hyperaccumulator Noccaea caerulescens (J. Presl and C. Presl) F. K. Mey. in Western Europe.
abstract: Noccaea caerulescens (Brassicaceae) is a major pseudometallophyte model for the investigation of the genetics and evolution of metal hyperaccumulation in plants. We studied the population genetics and demographic history of this species to advance the understanding of among-population differences in metal hyperaccumulation and tolerance abilities. Sampling of seven to 30 plants was carried out in 62 sites in Western Europe. Genotyping was carried out using a combination of new chloroplast and nuclear neutral markers. A strong genetic structure was detected, allowing the definition of three genetic subunits. Subunits showed a good geographic coherence. Accordingly, distant metallicolous populations generally belonged to distinct subunits. Approximate Bayesian computation analysis of demographic scenarios among subunits further supported a primary isolation of populations from the southern Massif Central prior to last glacial maximum, whereas northern populations may have derived during postglacial recolonization events. Estimated divergence times among subunits were rather recent in comparison with the species history, but certainly before the establishment of anthropogenic metalliferous sites. Our results suggest that the large-scale genetic structure of N. caerulescens populations pre-existed to the local adaptation to metalliferous sites. The population structure of quantitative variation for metal-related adaptive traits must have established independently in isolated gene pools. However, features of the most divergent genetic unit (e.g. extreme levels of Cd accumulation observed in previous studies) question the putative relationships between adaptive evolution of metal-related traits and subunits isolation. Finally, admixture signals among distant metallicolous populations suggest a putative role of human activities in facilitating long-distance genetic exchanges.
authors.affiliation: Laboratoire Sols et Environnement UMR1120, Université de Lorraine, TSA 40602, Vandœuvre-lès-Nancy Cedex, F-54518, France.|Laboratoire Sols et Environnement UMR1120, INRA, Vandœuvre-lès-Nancy Cedex, F-54518, France.
authors.forename: Cédric
authors.initials: C
authors.lastname: Gonneau
authors.affiliation: Laboratoire d'Écologie Végétale et Biogéochimie, Université libre de Bruxelles, Campus de la Plaine - CP244, Boulevard du Triomphe, B-1050, Ixelles, Belgium.
authors.forename: Nausicaa
authors.initials: N
authors.lastname: Noret
authors.affiliation: Univ. Lille, CNRS, UMR 8198 - Evo-Eco-Paleo, F-59000, Lille, France.
authors.forename: Cécile
authors.initials: C
authors.lastname: Godé
authors.affiliation: Univ. Lille, CNRS, UMR 8198 - Evo-Eco-Paleo, F-59000, Lille, France.
authors.forename: Hélène
authors.initials: H
authors.lastname: Frérot
authors.affiliation: Laboratoire Sols et Environnement UMR1120, Université de Lorraine, TSA 40602, Vandœuvre-lès-Nancy Cedex, F-54518, France.|Laboratoire Sols et Environnement UMR1120, INRA, Vandœuvre-lès-Nancy Cedex, F-54518, France.
authors.forename: Catherine
authors.initials: C
authors.lastname: Sirguey
authors.affiliation: Laboratoire Sols et Environnement UMR1120, Université de Lorraine, TSA 40602, Vandœuvre-lès-Nancy Cedex, F-54518, France.|Laboratoire Sols et Environnement UMR1120, INRA, Vandœuvre-lès-Nancy Cedex, F-54518, France.
authors.forename: Thibault
authors.initials: T
authors.lastname: Sterckeman
authors.affiliation: Univ. Lille, CNRS, UMR 8198 - Evo-Eco-Paleo, F-59000, Lille, France.
authors.forename: Maxime
authors.initials: M
authors.lastname: Pauwels
mesh_terms: D000222:Adaptation, Physiological / Q000235:genetics; D001499:Bayes Theorem; D019607:Brassicaceae / Q000235:genetics* / Q000378:metabolism; D005060:Europe; D005828:Genetics, Population; D005838:Genotype; D008670:Metals / Q000378:metabolism*
chemical_list: D008670:Metals
keywords: Approximate Bayesian computation; chloroplast DNA; local adaptation; nuclear microsatellite; phylogeography; pseudometallophyte