title: Evolution and Phylogenetic Diversity of Yam Species (Dioscorea spp.): Implication for Conservation and Agricultural Practices.
abstract: Yams (Dioscorea spp.) consist of approximately 600 species. Presently, these species are threatened by genetic erosion due to many factors such as pest attacks and farming practices. In parallel, complex taxonomic boundaries in this genus makes it more challenging to properly address the genetic diversity of yam and manage its germplasm. As a first step toward evaluating and preserving the genetic diversity yam species, we use a phylogenetic diversity (PD) approach that has the advantage to investigate phylogenetic relationships and test hypotheses of species monophyly while alleviating to the problem of ploidy variation within and among species. The Bayesian phylogenetic analysis of 62 accessions from 7 species from three regions of Cameroon showed that most Dioscorea sections were monophyletic, but species within sections were generally non-monophyletic. The wild species D. praehensilis and cultivated D. cayenensis were the species with the highest PD. At the opposite, D. esculenta has a low PD and future studies should focus on this species to properly address its conservation status. We also show that wild species show a stronger genetic structure than cultivated species, which potentially reflects the management of the yam germplasm by farmers. These findings show that phylogenetic diversity is a promising approach for an initial investigation of genetic diversity in a crop consisting of closely related species.
authors.affiliation: Laboratory of Plant Physiology, Higher Teacher's Training College, University of Yaoundé 1, P. O. Box 47, Yaounde, Cameroon.|Institute of Agricultural Research for Development-CEREFEN, BP 167, Meyomessala, Cameroon.
authors.forename: Marie Florence Sandrine
authors.initials: MF
authors.lastname: Ngo Ngwe
authors.affiliation: Laboratory of Plant Physiology, Higher Teacher's Training College, University of Yaoundé 1, P. O. Box 47, Yaounde, Cameroon.
authors.forename: Denis Ndoumou
authors.initials: DN
authors.lastname: Omokolo
authors.affiliation: Institut de recherche en biologie végétale, Montreal Botanical Garden and Université de Montréal, 4101 Sherbrooke East, Montréal, QC, H1X 2B2, Canada.
authors.forename: Simon
authors.initials: S
authors.lastname: Joly
mesh_terms: D000383:Agriculture; D001499:Bayes Theorem; D005075:Biological Evolution; D002163:Cameroon; D018556:Crops, Agricultural; D027742:Dioscorea / Q000235:genetics / Q000502:physiology*; D005819:Genetic Markers; D014644:Genetic Variation; D010802:Phylogeny
chemical_list: D005819:Genetic Markers