SIMILARITY IN HABITAT ADAPTATIONS OF ARCTIC AND AFRICAN UNGULATES: EVOLUTIONARY CONVERGENCE OR ECOLOGICAL DIVERGENCE?

Abstract

Caribout (Rangifer tarandus) and muskoxen (Ovibos moschatus) partition habitat use in the Arctic differently in relation to the morphological, physiological, and behavioral attributes. Adaptations to Arctic habitats by caribou result in an energy-costly lifestyle in contrast to the energy-conservative adaptations of muskoxen. In southern Africa, impala (Aepyceros melampus melampus) and blesbok (Damaliscus dorcas phillipsi) show parallel adaptations, with impala more closely mirroring caribou, and those adaptations of blesbok resembling muskoxen. Comparative abilities of these ungulates to adapt to habitat parameters derive from their morphological, physiological, and behavioral capacities. Habitat constraints determine energy-nutritive requirements, forage digestibility, forage selection and intake rates, locomotive efficiency, thermal regulation, water requirements, avoidance of predation, and insect harassment and parasitism. Although overlap occurs, or has occurred, in distribution of these geographically paired ungulate species in both the Arctic and southern Africa, partitioning of habitat use ahs been dependent on species-specific selection of microhabitat components.