Patterns of Niche Overlap Among Broadly Sympatric Versus Narrowly Sympatric Kalahari Lizards (Scincidae: Mabuya)

Two semiarboreal skinks (Mabuya) are narrowly sympatric in the Kalahari desert, whereas two terrestrial species are broadly sympatric both with one another and with the semiarboreal species. We attempt to discern reasons for these differing distributional patterns. The narrow zone of sympatry of the semiarboreal species is partially congruent with zones of habitat change (rainfall and vegetation), suggesting that the narrow zone probably reflects adaptations of these species of geographic discontinuities of the physical environment. However, the near identity of niches (position on sandridges, microhabitats, body temperatures, times of activity, as well as types and sizes of prey) of the semiarboreal species relative to other species pairs also suggest that intense competition could restrict the zone of sympatry.