Molecular systematics and biogeographic history of the African climbing-mouse complex (Dendromus).

Climbing mice in the genus Dendromus (sensu lato) are widely distributed in Africa, south of the Saharan Desert. The 17 currently recognized species in the genus range from widespread taxa to single-mountain endemics, and there is considerable variation across species with respect to habitats occupied. These habitats range from arid grasslands and savannahs to sub-alpine and alpine vegetation. Using the most comprehensive geographic and genetic survey to date and after reviewing many type specimens, we assess the systematics and biogeography of Dendromus. Given the structure of our molecular phylogenetic hypotheses, in which we recover six major clades, we propose the recognition of three genera within the Dendromus group (sensu lato): in addition to Dendromus (26 lineages), we suggest the retention of Megadendromus (monotypic) and the resurrection of the genus Poemys (six lineages). From our model-based molecular phylogenetic results and morphological comparisons, we suggest that six formerly synonymized taxa should be resurrected, and we highlight 14 previously undescribed lineages. We also constructed time-calibrations on our phylogeny, and performed ancestral area reconstructions using BioGeoBEARS. Based on fossil evidence, Dendromus appears to have had a widespread African distribution dating back to the Late Miocene (8-10 Ma), and our basal ancestral area reconstruction (Ethiopians Highlands + Eastern African Mountains + Zambezian region) supports this. Divergence of the six major clades we recover (Poemys, Megadendromus and four within Dendromus) occurred prior to or at the Miocene-Pliocene boundary 5.3 Ma. Biogeographically, Megadendromus is restricted to the Ethiopian Highlands. The ancestral area for Poemys is reconstructed as the Zambezian region, with species distributions ranging from South Africa to Western Africa. The ancestral area for Dendromus is reconstructed as the Ethiopian Highlands, with the ancestral areas of the four major clades being reconstructed as Ethiopian Highlands, Albertine Rift, South Africa or Western Africa. None of the four Dendromus clades are reciprocally monophyletic with respect to distributional area.