title: Ethnolinguistic structuring of sorghum genetic diversity in Africa and the role of local seed systems.
abstract: Sorghum is a drought-tolerant crop with a vital role in the livelihoods of millions of people in marginal areas. We examined genetic structure in this diverse crop in Africa. On the continent-wide scale, we identified three major sorghum populations (Central, Southern, and Northern) that are associated with the distribution of ethnolinguistic groups on the continent. The codistribution of the Central sorghum population and the Nilo-Saharan language family supports a proposed hypothesis about a close and causal relationship between the distribution of sorghum and languages in the region between the Chari and the Nile rivers. The Southern sorghum population is associated with the Bantu languages of the Niger-Congo language family, in agreement with the farming-language codispersal hypothesis as it has been related to the Bantu expansion. The Northern sorghum population is distributed across early Niger-Congo and Afro-Asiatic language family areas with dry agroclimatic conditions. At a finer geographic scale, the genetic substructure within the Central sorghum population is associated with language-group expansions within the Nilo-Saharan language family. A case study of the seed system of the Pari people, a Western-Nilotic ethnolinguistic group, provides a window into the social and cultural factors involved in generating and maintaining the continent-wide diversity patterns. The age-grade system, a cultural institution important for the expansive success of this ethnolinguistic group in the past, plays a central role in the management of sorghum landraces and continues to underpin the resilience of their traditional seed system.
authors.affiliation: Centre for Development and the Environment, University of Oslo, NO-0317 Oslo, Norway; Centre for Ecological and Evolutionary Synthesis, Department of Biosciences, University of Oslo, NO-0316 Oslo, Norway;
authors.forename: Ola T
authors.initials: OT
authors.lastname: Westengen
authors.affiliation: Ministry of Agriculture, Eastern Equatoria State, Torit, South Sudan;
authors.forename: Mark Atam
authors.initials: MA
authors.lastname: Okongo
authors.affiliation: College of Applied and Industrial Sciences, Juba University, Juba, South Sudan;
authors.forename: Leo
authors.initials: L
authors.lastname: Onek
authors.affiliation: Noragric, Norwegian University of Life Sciences, NO-1432 Aas, Norway;
authors.forename: Trygve
authors.initials: T
authors.lastname: Berg
authors.affiliation: International Crops Research Institute for the Semi-Arid Tropics, Patancheru 502 324, India; Department of Agronomy, Kansas State University, Manhattan, KS 66506; and UWA Institute of Agriculture, University of Western Australia, Crawley, WA 6009, Australia.
authors.forename: Hari
authors.initials: H
authors.lastname: Upadhyaya
authors.affiliation: Centre for Ecological and Evolutionary Synthesis, Department of Biosciences, University of Oslo, NO-0316 Oslo, Norway;
authors.forename: Siri
authors.initials: S
authors.lastname: Birkeland
authors.affiliation: Centre for Ecological and Evolutionary Synthesis, Department of Biosciences, University of Oslo, NO-0316 Oslo, Norway;
authors.forename: Siri Dharma
authors.initials: SD
authors.lastname: Kaur Khalsa
authors.affiliation: Centre for Development and the Environment, University of Oslo, NO-0317 Oslo, Norway;
authors.forename: Kristoffer H
authors.initials: KH
authors.lastname: Ring
authors.affiliation: Centre for Ecological and Evolutionary Synthesis, Department of Biosciences, University of Oslo, NO-0316 Oslo, Norway; n.c.stenseth@ibv.uio.no.
authors.forename: Nils C
authors.initials: NC
authors.lastname: Stenseth
authors.affiliation: Centre for Ecological and Evolutionary Synthesis, Department of Biosciences, University of Oslo, NO-0316 Oslo, Norway;
authors.forename: Anne K
authors.initials: AK
authors.lastname: Brysting
mesh_terms: D000349:Africa; D057231:Climate Change; D018556:Crops, Agricultural / Q000145:classification / Q000235:genetics*; D003466:Cultural Characteristics; D018744:DNA, Plant / Q000235:genetics; D017753:Ecosystem; D005006:Ethnicity; D014644:Genetic Variation; D006801:Humans; D007802:Language; D018895:Microsatellite Repeats; D008957:Models, Genetic; D012639:Seeds / Q000235:genetics; D045868:Sorghum / Q000145:classification / Q000235:genetics*
chemical_list: D018744:DNA, Plant
keywords: cultural selection; genetic resources; social–ecological adaptation