Past, present, and future distribution of Afromontane rodents (Muridae: Otomys) reflect climate-change predicted biome changes

Abstract

Climate change constitutes a potential threat to montane biodiversity, particularly in low-altitude, tropical mountains; however, few data exist for the Afromontane taxa. In South Africa, the temperate grassland and fynbos biomes are mostly associated with the Great Escarpment and the high-lying central plateau. Varying contractions of the grassland and fynbos biomes are predicted under different climate scenarios by 2050. Animal taxa adapted to these biomes should suffer similar range declines and can be used to independently test the vegetation models. We constructed MaxEnt models from 271 unique locality records for three species of montane and submontane vlei rats that are closely associated with grassland (Otomys auratus, Wroughton 1906), mesic savanna (Otomys angoniensis, Wroughton 1906), and fynbos (Otomys irroratus, Brants 1827) biomes in South Africa. Projected range shifts under the A2 emission scenario of the Intergovernmental Panel on Climate Change showed increases (O. angoniensis) and decreases (O. auratus) that closely mirrored those expected for the savanna and grassland biomes, respectively. Comparison of historical (from 90 years ago) and current occurrence data from a zone of sympatry in the tropical Soutpansberg Mountains (at 1250 m asl) showed complete replacement of the grassland-adapted rodent species (O. auratus) by the savanna-adapted species (O. angoniensis) due to historically documented changes from a grassland-dominated to thicket-dominated landscape.