Genetic Diversity and Structure of Acacia senegal (L.) Willd. in Uganda

The study assessed the genetic variation and population structure of Acacia senegal in Uganda. Based on 129 mature individuals, representing eight populations, the genetic variation and population structure of Acacia senegal in Uganda was analysed at four microsatellite loci. All four loci were highly variable, with the number of alleles per locus ranging from 8-14 (mean = 10.5). Substantial levels of genetic diversity were found (mean expected heterozygosity, He = 0.479, range 0.245-0.846; Information Index, I = 0.927, range 0.646-1.206). Analysis of molecular variance demonstrated moderate genetic differentiation among populations [Fst = 0.100, p≤ 0.001], comparable to similar tropical species. Isolation by distance, based on Mantel Test showed a positive and significant correlation [Rxy = 0.197, p≤0.001]. Based on population assignment, pair-wise population comparisons and PCA, four populations emerged; one on the eastern and the other on the western side of lake Kyoga, suggesting isolation due to a water body barrier; two other populations emerged in Karamoja. The observed southern-northern flowering pattern across the species distribution range appears central to the species differentiation. The four populations, therefore, form the target for conservation and sustainable utilization of the species genetic variability in Uganda.