ASSESSMENT OF GENETIC DIVERSITY WITHIN AND BETWEEN POPULATIONS OF DIOSCOREA ABYSSINICA HOCHST. EX KUNTH OF NORTHERN BENIN USING AFLP (AMPLIFIED FRAGMENT LENGTH POLYMORPHISM) MARKERS

Cultivated yams belonging to D. cayenensis – D. rotundata complex (also referred as to guinea yams) are known to be domesticated from some related wild species among which, Dioscorea abyssinica which naturally occurs in the savannahs of northern Benin. To select site for in situ conservation of the natural populations of this species, AFLP was used to assess the existing genetic diversity and its structuring within and between populations of Pendjari and Oueme Superieur (two natural reserves of the northern Benin). AFLP revealed high genetic diversity within and between both analysed populations. These populations appeared genetically distinct and therefore, represent two different genetic entities that should be separately and equally conserved. Within population, the genetic diversity is uniformly distributed indicating the possibility of focussing conservation activities only on the core zone of the reserves without fear. By combining the genetic diversity data with existing ecological information and taking into account the relative position of the preselected natural reserves, Pendjari and Oueme Superieur have been selected for the in situ conservation of Dioscorea abyssinica in Benin. Les ignames cultivees du complexe Doscorea cayenensis-Dioscorea rotundata sont issues de domestication ancienne ou recente d’especes sauvages apparentees parmi lesquelles Dioscorea abyssinica qui existe en populations naturelles dans les savanes du Nord Benin (au dela du 9eme parallele). Dans le but d’identifier des sites pour laconservation in situ des populations naturelles de cette espece, la technique d’analyse moleculaire AFLP a ete utilisee pour evaluer la diversite genetique au sein et entre populations de Dioscorea abyssinica de deux sites preselectionnes que sont le Parc national de la Pendjari et la Foret classee de l’Oueme Superieur. L’AFLP a revele une importante diversite genetique intra et inter populations. Les deux populations analysees sont apparues genetiquement distantes et constituent donc deux entites differentes a conserver separement. Aucune compartimentation genetique n’est observee au sein des populations analysees et par consequent les efforts de conservation in situ pourraient etre uniquement concentrees au coeur des reserves. Le resultat des analyses genetiques associe aux donnees ecologiques existantes a conduit au choix du parc national de la Pendjarai et de la foret classee de l’Oueme Superieur pour la conservation in situ de Dioscorea abyssinica au Benin