Small terrestrial mammals of southern Ethiopia: DNA barcoding sheds light on a neglected centre of montane endemism

Abstract

Abstract The Ethiopian Highlands (EH) represent one of the most outstanding centres of endemism in Africa. There is an important biogeographical structure of EH, driven by the presence of the Great Rift Valley (GRV) and deep river valleys, promoting diversification of biota. Here we focused on small mammals of the Wolaita and Gamo zones in the southern part of EH, eastward of GRV. We DNA-barcoded all taxa and combined the new data with previous sequences from other parts of EH and elsewhere. Based on the phylogeographic patterns, we assess the role of GRV in southern Ethiopia as a barrier to gene flow (in montane taxa) or as a corridor facilitating gene flow (in lowland taxa from savanna). We show that the bottom of GRV is inhabited by a unique mix of taxa from the Sudanian and Somali-Masai savannas. The mountains are inhabited (i) by species widely distributed on both sides of GRV, (ii) by species restricted to remnant forests of south-western EH, and (iii) by specialists of Afroalpine habitats, including one possibly new species of Lophuromys . The high diversity of indigenous ecosystems is significantly threatened by an increasing human population and by invasive commensal mammals, mainly the black rat Rattus rattus .