Genetic diversity and phylogeography of wild-sown and cultivated coconuts (Cocos nucifera L.)

Gunn Bee F., Crisp Michael, Baudouin Luc, Olsen Kenneth M.. 2011. Genetic diversity and phylogeography of wild-sown and cultivated coconuts (Cocos nucifera L.). In : IBC2011. XVIII International Botanical Congress, 23-30 July 2011, Melbourne, Australia. s.l. : s.n., Résumé, 600. International Botanical Congress. 18, Melbourne, Australie, 23 Juillet 2011/30 Juillet 2011.

Résumé : The coconut (Cocos nucifera L.) is a pantropical strand plant, colonizing sandy insular beaches in the humid tropics. Cocos is a monotypic genus in the Cocoseae tribe (18/ca. 200 spp.) within the Arecaceae family. Phylogenetic studies support its sister relationship to Syagrus, a Neotropical genus, sharing a common ancestor about 35 MYBP, though the crown group age of Cocos is about 11 MYBP. Fossil evidence indicates that members of the Cocos lineage were present in South America, India, New Zealand and Australia. Coconuts are adapted to drift-dispersal by ocean currents; however, human activities both historically and today have also aided its spread and impacted its phenotypic and genetic structure. Coconuts are traditionally classified as 'Talls' or 'Dwarfs' based on tree habit. Morphological examination reveal two predominant fruit types, attributed to Polynesian terminology: niu kafa are characterized by their elongated, triangular fruits with large proportion of fibrous husk and niu vai, whose fruits are rounded with large proportion of liquid endosperm. The niu kafa form is interpreted as the naturally evolved coconut, under natural selection for dissemination by sea currents whilst the niu vai form evolved from domestication under human selection for greater volume of delicious coconut water. Here we investigate the genetic diversity of coconuts, the impact of domestication, introgression and the taxonomic implications for this species. We used polymorphic microsatellite markers on 1322 coconut samples representing phenotypic and genetic variation worldwide to examine the geographical location of the center(s) of domestication and its progenitors. Bayesian analyses of population structure revealed two major subpopulations corresponding to the Pacific and Indo-Atlantic oceanic regions. Haplotype networks based on chloroplast and nuclear markers are used as a complementary dataset to examine the coconut's phylogeography. (Texte intégral)

Mots-clés Agrovoc : Cocos nucifera, variation génétique, phylogénie, distribution géographique

Mots-clés géographiques Agrovoc : Océanie, océan Pacifique, Amérique du Sud, Inde, Australie, Nouvelle-Zélande

Classification Agris : F70 - Taxonomie végétale et phytogéographie
F30 - Génétique et amélioration des plantes

Auteurs et affiliations

• Gunn Bee F., ANU (AUS)
• Crisp Michael, ANU (AUS)
• Baudouin Luc, CIRAD-BIOS-UMR AGAP (FRA)
• Olsen Kenneth M., Washington University (USA)

Source : Cirad - Agritrop (https://agritrop.cirad.fr/561976/)

Métriques

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