Evolutionary history and species diversity of A frican pouched mice ( R odentia: N esomyidae: S accostomus )

• Published in: Zoologica scripta 2016-11, Vol.45 (6), p.595-617
• Main Authors: Mikula, Ondřej, Šumbera, Radim, Aghová, Tatiana, Mbau, Judith S., Katakweba, Abdul S., Sabuni, Christopher A., Bryja, Josef
• Format: Article
• Language: English
• ISSN: 0300-3256; 1463-6409
• DOI: 10.1111/zsc.12179

We explore diversity of A frican pouched mice, genus S accostomus ( R odentia, N esomyidae), by sampling molecular and morphological variation across their continental‐scale distribution in southern and eastern A frican savannahs and woodlands. Both mitochondrial (cytochrome b) and nuclear DNA ( IRBP , RAG 1) as well as skull morphology confirm the distinction between two recognized species, S . campestris and S . mearnsi , with disjunct distribution in the Z ambezian and S omali– M aasai bioregions, respectively. Molecular dating suggests the divergence of these taxa occurred in the E arly P liocene, 3.9 Ma before present, whereas the deepest divergences within each of them are only as old as 2.0 Ma for S . mearnsi and 1.4 Ma for S . campestris . Based on cytochrome b phylogeny, we defined five clades (three within S . campestris , two in S . mearnsi ) whose species status was considered in the light of nuclear DNA markers and morphology. We conclude that S . campestris group consists of two subspecies S . campestris campestris ( P eters, 1846; comprising two cytochrome b clades) and S . campestris mashonae (de W inton, 1897) that are moderately differentiated, albeit distinct in IRBP and skull form. They likely hybridize to a limited extent along the K afue– Z ambezi R ivers. S accostomus mearnsi group consists of two species, S . mearnsi ( H eller, 1910) and S . umbriventer ( M iller, 1910), that are markedly differentiated in both nuclear markers and skull form and may possibly co‐occur in south‐western K enya and north‐eastern T anzania. Analysis of historical demography suggests both subspecies of S . campestris experienced population expansion dated to the L ast G lacial. In the present range of S . campestris group, the distribution modelling suggests a moderate fragmentation of suitable habitats during the last glacial cycle, whereas in the range of S . mearnsi group it predicts substantial shifts of its occurrence in the same period.