Genetic differentiation in Khaya Ivorensis A. Chev., a threaten tree of evergreen African rainforests

Bouka-Dipelet Ulrich Gael, Doumenge Charles, Ekué Marius Rodrigue Mensah, Duminil Jérôme, Florence Jacques, Degen Bernd, Loumeto Jean-Joël, McKey Doyle B., Hardy Olivier J.. 2024. Genetic differentiation in Khaya Ivorensis A. Chev., a threaten tree of evergreen African rainforests. Tree Genetics and Genomes, 20:41, 14 p.

Url - jeu de données - Entrepôt autre : https://doi.org/10.5281/zenodo.7901654

Résumé : Phylogeographic studies on widespread rainforest species from West and Central Africa often reveal genetic discontinuities. These discontinuities can originate from past barriers to gene flow resulting from long-lasting population fragmentation during glacial periods, according to the forest refuge hypothesis. This study 69 nuclear SNPs, 13 plastid SNPs, and 24 mitochondrial SNPs to characterized the distribution of genetic diversity in 377 individuals of the widespread tropical tree Khaya ivorensis, in western and central African evergreen forests. Two very well-differentiated nuclear genetic clusters (FST = 0.28) are located respectively in West and Central Africa. The gradual transition of allele frequencies between the clusters across a broad geographic area going from Cameroon to Nigeria accords with the recognition of a single species, although we show an incipient divergence that could eventually lead to the separation of two taxa. The two clusters have similar genetic diversity at nuclear SNPs. However, the cytoplasmic data revealed high haplotypic diversity and numerous endemic haplotypes in Central Africa, and only one widespread haplotype in West Africa, suggesting an ancient colonization of West Africa from Central Africa. The genetic diversity inside and outside putative forest refugia (Anhuf et al., Palaeogeogr Palaeoclimatol Palaeoecol 239:510–527, 2006) does not differ significantly in either genetic cluster. Hence, we cannot confirm that forest refugia played a particular role in the pattern of distribution of genetic diversity in K. ivorensis. Owing to the high haplotypic diversity of their populations, Central Africa, especially Gabon, constitutes a priority area for the conservation of the genetic diversity of K. ivorensis.

Mots-clés Agrovoc : variation génétique, forêt tropicale humide, génétique des populations, biodiversité, Khaya, forêt tropicale, génétique mitochondriale

Mots-clés géographiques Agrovoc : Cameroun, Afrique centrale, Gabon, Afrique occidentale, Afrique, Nigéria, République centrafricaine, Bénin

Mots-clés libres : Khaya ivorensis, Phylogeography, Species delimitation, Population genetics, Forest refugia, Phytogeographic barriers

Agences de financement européennes : European Commission

Agences de financement hors UE : Ambassade de France au Congo, International Foundation for Science, Conservation Action Research Network, Centre de Coopération Internationale en Recherche Agronomique pour le Développement, German Federal Ministry of Food and Agriculture, International Tropical Timber Organization, Prince Albert II of Monaco Foundation, Agence Nationale de la Recherche

Projets sur financement : (JPN) ITTO, (FRA) Plateforme d'Innovation "Forêt-Bois-Fibre-Biomasse du Futur"

Auteurs et affiliations

• Bouka-Dipelet Ulrich Gael, CIRAD-ES-UPR Forêts et sociétés (FRA) - auteur correspondant
• Doumenge Charles, CIRAD-ES-UPR Forêts et sociétés (FRA)
• Ekué Marius Rodrigue Mensah, Bioversity International (CMR)
• Duminil Jérôme, IRD (FRA)
• Florence Jacques, MNHN (FRA)
• Degen Bernd, Thünen Institute of Forest Genetics (DEU)
• Loumeto Jean-Joël, UMNG (COG)
• McKey Doyle B., CNRS (FRA)
• Hardy Olivier J., ULB (BEL)

Source : Cirad-Agritrop (https://agritrop.cirad.fr/611715/)

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