Past climate changes explain the phylogeography of Vitellaria paradoxa over Africa

Allal François, Sanou Haby, Millet Laurent, Vaillant Alexandre, Camus-Kulandaivelu Létizia, Logossa Zénor Ablah, Lefèvre François, Bouvet Jean-Marc. 2011. Past climate changes explain the phylogeography of Vitellaria paradoxa over Africa. Heredity, 107 (2) : 174-186.

https://doi.org/10.1038/hdy.2011.5

Article de revue ; Article de revue à facteur d'impact

Version publiée - Anglais
Accès réservé aux personnels Cirad
Utilisation soumise à autorisation de l'auteur ou du Cirad.
document_560732.pdf
Télécharger (813kB)

Quartile : Q1, Sujet : ECOLOGY / Quartile : Q1, Sujet : GENETICS & HEREDITY / Quartile : Q2, Sujet : EVOLUTIONARY BIOLOGY

Résumé : The evolution of the savanna biome has been deeply marked by repeated contraction/expansion phases due to climate perturbations during the Quaternary period. In this study, we investigated the impact of the last glacial maximum (LGM) on the present genetic pattern of Vitellaria paradoxa (shea tree), a major African savanna tree. A range-wide sampling of the species enabled us to sample 374 individuals from 71 populations distributed throughout sub-Sahelian Africa. Trees were genotyped using 3 chloroplasts and 12 nuclear microsatellites, and were sequenced for 2 polymorphic chloroplast intergenic spacers. Analyses of genetic diversity and structure were based on frequency-based and Bayesian methods. Potential distributions of V. paradoxa at present, during the LGM and the last interglacial period, were examined using DIVA-GIS ecological niche modelling (ENM). Haplotypic and allelic richness varied significantly across the range according to chloroplast and nuclear microsatellites, which pointed to higher diversity in West Africa. A high but contrasted level of differentiation was revealed among populations with a clear phylogeographic signal, with both nuclear (FST¼0.21; RST¼0.28; RST4RST (permuted)) and chloroplast simple sequence repeats (SSRs) (GST¼0.81; NST¼0.90; NST4NST (permuted)). We identified a strong geographically related structure separating western and eastern populations, and a substructure in the eastern part of the area consistent with subspecies distinction. Using ENM, we deduced that perturbations during the LGM fragmented the potential eastern distribution of shea tree, but not its distribution in West Africa. Our main results suggest that climate variations are the major factor explaining the genetic pattern of V. paradoxa.

Mots-clés Agrovoc : Vitellaria paradoxa, changement climatique

Mots-clés géographiques Agrovoc : Afrique au sud du Sahara

Classification Agris : F40 - Écologie végétale
F30 - Génétique et amélioration des plantes
P40 - Météorologie et climatologie

Champ stratégique Cirad : Axe 1 (2005-2013) - Intensification écologique

Auteurs et affiliations