Cladogenesis and endemism in Tanzanian mole-rats, genus Fukomys: (Rodentia: Bathyergidae): a role for tectonics? CHRIS G. FAULKES 1 *, GEORGIES F. MGODE 2 , STEVEN C. LE COMBER 1 and NIGEL C. BENNETT 3 1 Queen Mary University of London, School of Biological and Chemical Sciences, Mile End Road, London, E1 4NS, UK 2 Pest Management Centre, Sokoine University of Agriculture, PO Box 3110, Chuo Kikuu, Morogoro, Tanzania 3 Mammal Research Institute, Department of Zoology and Entomology, University of Pretoria, Pretoria 0002, South Africa Received 5 October 2009; accepted for publication 14 November 2009 African mole-rats of the family Bathyergidae are subterranean hystricomorph rodents found throughout sub- Saharan Africa, where the distributional ranges of the most speciose taxa are divided by the African Rift Valley. In particular, mole-rats of the genera Heliophobius and Fukomys are distributed widely, and their adaptive radiation appears to have been strongly influenced by the geological process of rifting. As a result, virtually all members of the genus Fukomys occur in locations west of the Rift Valley. However, a small number of isolated populations occur east of the Rift Valley in Tanzania, where Heliophobius is widespread and is the predominant bathyergid rodent. Phylogenetic analysis of mitochondrial cytochrome b sequences of previously unstudied Tanzanian mole-rats (genus Fukomys) and geographically adjacent populations strongly suggests that vicariance in the Western Rift Valley has subdivided populations of mole-rats and, together with climatic changes, played a role in the isolation of extralimital populations of Fukomys in Tanzania. Together with molecular clock-based estimates of divergence times, these results offer strong support for the hypothesis that the observed patterns of cladogenesis are consistent with tectonic activity in the ‘Mbeya triple junction’ and Rungwe volcanic province between Lakes Rukwa and Nyasa. © 2010 The Linnean Society of London, Biological Journal of the Linnean Society, 2010, 100, 337–352. ADDITIONAL KEYWORDS: African mole-rats – Eastern Arc Mountains – mitochondrial DNA – phylogeography – Rift Valley. INTRODUCTION Although much attention has been given to the inves- tigation of cladogenesis and speciation resulting from plate tectonics in the Great Rift Valley lakes of Africa, relatively little has been reported on such effects on terrestrial organisms. Classic studies of the cichlid fishes in Lakes Victoria, Nyasa and Tanganyika (e.g. Salzburger et al., 2005) have shown that the coloni- zation of these vast expanses of water from the surrounding river systems has led to explosive adap- tive radiations and remarkable levels of speciation and endemism. Although the Great Rift Valley began its formation about 50 Mya, major rifting occurred in the Miocene and continued through the Pliocene and Pleistocene, producing the great African lakes, mountains and volcanoes that characterize East Africa (for a recent review, see Chorowicz, 2005). Of particular relevance to this study are the Western and Southern Rift areas, including Lakes Tanganyika and Nyasa, respectively, and the intervening corridor of land between them connecting Zambia, Malawi and *Corresponding author. E-mail: c.g.faulkes@qmul.ac.uk Biological Journal of the Linnean Society, 2010, 100, 337–352. With 5 figures © 2010 The Linnean Society of London, Biological Journal of the Linnean Society, 2010, 100, 337–352 337 Downloaded from https://academic.oup.com/biolinnean/article-abstract/100/2/337/2450518 by guest on 05 June 2020