A Re-Appraisal of Palaeoenvironmental History in Central Africa: Evidence for a Major Fluvial Refuge in the Zaire Basin

Pleistocene refuge theory has been strengthened in the Neotropics by much prominent and recent work. In contrast, models developed in the 1960s for Central African tropics are still retained to-day. Because these were based on knowledge of highland palaeoenvironments and biogeography, and on an almost blank page for lowland forests of the Central Zaire Basin, the discrimination between lowland and montane faunas remained imprecise, and their relative histories somewhat confused. Results of a 5-year study on primate distribution and systematics in the Zaire Basin do not support the previously proposed diversity gradients, and show that the so-called East Central major refuge was drawn from the addition of allopatric faunas. We point out the high specific richness and endemism of lowland forests on both sides of the Zaire River, and suggest the existence of a quaternary Major Fluvial Refuge. The validity of the palaeoenvironmental history currently proposed for Central Africa, especially the extent of lowering of montane forest and the degree of persistence of lowland forest, is questioned.