Evidence of high genetic diversity and significant population structuring in Vachellia tortilis (Forsk.) Galasso & Banfi population in Kenya

• Published in: Annals of forest science. Vol. 76; no. 2
• Main Authors: Omondi, Stephen F., Machua, Joseph, Muturi, Gabriel M., Gicheru, John M., Hanaoka, So
• Format: Journal Article
• Language: English
• Published: Paris Springer Paris 01.06.2019; Springer Nature B.V; Springer Nature (since 2011)/EDP Science (until 2010)
• Subjects: Biodiversity; Biomedical and Life Sciences; Breeding; Clusters; Conservation; Demographics; Deoxyribonucleic acid; Dispersal; DNA; Environment; Fodder; Forestry; Forestry Management; Gene flow; Genetic diversity; Genetic markers; Genetic resources; Genetics; Leaves; Life Sciences; Markers; Microsatellites; Migrants; Natural populations; Population; Population differentiation; Population genetics; Population structure; Populations; Research Paper; Resource management; Species; Species diversity; Tissues; Tree Biology; Trees; Wildlife conservation; Wood Science & Technology; Kenya; Gene flow; Genetic structure; Habitat disturbances; Nuclear microsatellites; Conservation strategy; Vachellia tortilis
• ISSN: 1286-4560; 1297-966X
• DOI: 10.1007/s13595-019-0834-y

Key message High genetic diversity and significant population structure of Vachellia tortilis population in Kenya has been determined using nuclear microsatellite markers. Despite wide distribution and long-distance gene dispersal of the species, geographic barriers affect its gene flow patterns. The Gregorian Rift Valley that cuts across the country is suggested to have differentiated the populations into eastern and western clusters. Context Vachellia tortilis is an important dryland tree species valued for fuelwood and fodder production; however, no strategy has been put in place for sustainable management of the species genetic resources. Furthermore, there is inadequate information on the species population genetics to aid the development of such strategies. Aims We evaluated the amount and structure of neutral genetic diversity of V. tortilis population in Kenya and provided recommendations necessary for improvement and conservation of the species genetic resources. We hypothesized that the current genetic diversity of V. tortilis is high because of its demographic history and that no population structuring was expected to occur due to the presumed long-distance and effective gene flow patterns within the species. Methods Leaf tissues were collected from 15 putative natural populations of V. tortilis covering the whole distribution range in Kenya. DNA was isolated from the leaf tissues and analyzed using microsatellite markers. In total, 450 trees were genotyped using ten polymorphic nuclear microsatellite loci, and genetic diversity and population structure parameters were determined. Results We found high levels of genetic diversity within the populations with a mean gene diversity at 0.85. However, significant population differentiation was evident ( F ST = 0.026, P = 0.007; R ST = 0.032, P = 0.004) despite a large number of migrants per generation ( N m = 5.3). Population structure detected suggests the presence of two clusters, although many individuals showed mixed ancestry. The groups reflect the influence of geographic patterns and historical population gene flow. Conclusion There exists high genetic diversity in V. tortilis in Kenya with significant population structuring into two clusters. We recommend the consideration of the two distinct groups in the development of the species improvement, breeding, and conservation programs. Such programs should ensure maintenance of the majority of the extant genetic diversity.