Species living in East African montane forests have highly fragmented distributions.
Plio-Pleistocene climatic cycles, however, may have allowed temporary contact between forest blocks, thereby allowing gene flow. Our aim was to reconstruct the colonization history of Praomys delectorum, a rodent species adapted to montane forests. We tested two alternative scenarios: (1) the occurrence of a series of vicariance events related to Quaternary climatic changes; and (2) colonization from a single origin through successive dispersal events. Analyses were based on large-scale sampling covering the complete range of the species distribution. Using the combination of genetic and morphological approaches we found out, that populations of P. delectorum are genetically differentiated along the north–south axis of the distribution range, consistent with postulated vicariance events. The oldest vicariance event, which separated the species into three main genetic groups, dates to the beginning of the Pleistocene. Further fragmentation within the three main lineages is consistent with successive vicariance events, probably linked to Pleistocene climatic cycles. Morphological variation between geographically structured populations may indicate local environmental adaptations.
Obtained results help to understand the evolutionary processes in unique ecosystem of eastern Afromontane forests and to define the conservation priorities in this important but endangered area of world biodiversity.