title: Past and present dynamics of sorghum and pearl millet diversity in Mount Kenya region.
abstract: Crop populations in smallholder farming systems are shaped by the interaction of biological, ecological, and social processes, occurring on different spatiotemporal scales. Understanding these dynamics is fundamental for the conservation of crop genetic resources. In this study, we investigated the processes involved in sorghum and pearl millet diversity dynamics on Mount Kenya. Surveys were conducted in ten sites distributed along two elevation transects and occupied by six ethnolinguistic groups. Varieties of both species grown in each site were inventoried and characterized using SSR markers. Genetic diversity was analyzed using both individual- and population-based approaches. Surveys of seed lot sources allowed characterizing seed-mediated gene flow. Past sorghum diffusion dynamics were explored by comparing Mount Kenya sorghum diversity with that of the African continent. The absence of structure in pearl millet genetic diversity indicated common ancestry and/or important pollen- and seed-mediated gene flow. On the contrary, sorghum varietal and genetic diversity showed geographic patterns, pointing to different ancestry of varieties, limited pollen-mediated gene flow, and geographic patterns in seed-mediated gene flow. Social and ecological processes involved in shaping seed-mediated gene flow are further discussed.
authors.affiliation: UMR AGAP CIRAD Montpellier France; Present address: UPR GREEN CIRAD 34398 Montpellier France.
authors.forename: Vanesse
authors.initials: V
authors.lastname: Labeyrie
authors.affiliation: UMR AGAP CIRAD Montpellier France.
authors.forename: Monique
authors.initials: M
authors.lastname: Deu
authors.affiliation: Ecologie, Systématique et Evolution UMR 8079 CNRS Université Paris-Sud Orsay France; Present address: UMR 1065 Santé et Agroécologie du Vignoble INRA 33140 Villenave d'Ornon France.
authors.forename: Yann
authors.initials: Y
authors.lastname: Dussert
authors.affiliation: KALRO Embu Kenya.
authors.forename: Bernard
authors.initials: B
authors.lastname: Rono
authors.affiliation: Ecologie, Systématique et Evolution UMR 8079 CNRS Université Paris-Sud Orsay France; Department of Biologie UVSQ Versailles France.
authors.forename: Françoise
authors.initials: F
authors.lastname: Lamy
authors.affiliation: KALRO Embu Kenya; Present address: CIMMYT 00621 Nairobi Kenya.
authors.forename: Charles
authors.initials: C
authors.lastname: Marangu
authors.affiliation: ICRISAT Nairobi Kenya; Present address: ABCIC P.O. Box 100882-00101 Nairobi Kenya.
authors.forename: Dan
authors.initials: D
authors.lastname: Kiambi
authors.affiliation: UMR AGAP CIRAD Montpellier France.
authors.forename: Caroline
authors.initials: C
authors.lastname: Calatayud
authors.affiliation: UMR AGAP CIRAD Montpellier France.
authors.forename: Geo
authors.initials: G
authors.lastname: Coppens d'Eeckenbrugge
authors.affiliation: Ecologie, Systématique et Evolution UMR 8079 CNRS Université Paris-Sud Orsay France; Sorbonne Universités, UPMC Univ Paris 06, IFD Paris Cedex 05 France.
authors.forename: Thierry
authors.initials: T
authors.lastname: Robert
authors.affiliation: UMR AGAP CIRAD Montpellier France.
authors.forename: Christian
authors.initials: C
authors.lastname: Leclerc
keywords: crop diversity; farmers’ seed systems; gene flow; population genetics; social organization