  We attempted to test biogeographic hypotheses proposed for the evolution of
tropical faunas using mitochondrial DNA sequences of selected African mammalian
taxa (Insectivora, Rodentia and Primates). 1/ we constructed a molecular
phylogeny of taxa in order to ascertain their monophyly and calibrate a
molecular clock; 2/ we analysed and compared the phylogeographic patterns of
five forest-dwelling taxa; 3/ we evaluated the evolutionary processes
potentially involved in the speciation of cercopithecine Primates. Phylogenetic
results confirm that gene history is not necessarily the same as organism
history. Phylogeographic analyses reveal distinct patterns for each model
species, suggesting differences in initial distributions or different responses
to the same events. They indicate a role of Plio-Pleistocene vicariance events
in the intra-specific diversification of small mammals. Thus, genetic
divergence would be much older than the last glacial cycles. In cercopithecine
Primates, speciation would have been predominantly allopatric and driven by
Miocene and Pliocene vicariance events. Altogether, results give support to the
refuge hypothesis, without excluding the riverine barrier nor the
paleogrographic ones. They emphasize the role of paleo-ecological changes in
generating diversity and of the main riverine barriers in shaping the present
distribution of that diversity.

Populations and Evolution