Honeybees, Apis mellifera Linnaeus (Hymenoptera : Apidae), of the Drakensberg mountains in relation to neighbouring populations

Multivariate morphometric analyses were performed on measurements of nine characteristics of 4011 worker bees from natural populations of the Drakensberg mountains and surrounding areas in southern Africa between 28 and 34 S latitude and 25 and 31 E longitude. A discriminant function analysis yielded three morphoclusters: group 1 comprising an unnamed population at higher than 1500 m altitude in the mountains; group 2 consisting of bees considered to be A. m. scutellata x A. m. capensis hybrids, and group 3 consisting of A. m. scutellata surrounding the mountains at lower (less than 1500 m) altitudes. The bees of group 1 show size similarities to disjunct populations of other large Afromontane bees, A. m. monticola. Group 2 hybrid bees occur in an area of marked climatic variability and manifest significantly high variances in their morphometrics, pheromones and DNA characteristics. It is suggested that differences in swarming seasons among these populations effectively cause temporal reproductive isolation between the group 1 mountain bees and those A. m. scutellata below the escarpment.