Allozyme variation in five populations of mopane, Colophospermum mopane (Fabaceae)

Ecological variants and morphological ecotypes are known in Colophospermum mopane which suggest phenotypic plasticity and possible genetic differentiation within the species. Five populations of C. mopane were studied to determine the levels of allozyme variation within and among them. Average heterozygosity values at 19 enzyme-coding loci in four populations varied little (H=1.2% to 2.1%) with a much higher value (6.1%) in the Messina population. Polymorphism levels were the same for all populations as measured by the average number of alleles per locus (1.2) and the percentage of polymorphic loci (15.8%). Pair-wise fixation index (FST=0.001 to 0.004), gene flow (Nem=39.840 to 159.840) and genetic distance (D=0.0002 to 0.0003) values indicate that four of the populations can be considered a single panmictic group, but that Messina is sufficiently diverged to regard it as a separate population. Results are discussed with specific reference to the conservation of the genetic integrity of C. mopane due to extensive exploitation by man.