Intraspecific differentiation and phylogeography of the Damaraland mole-rat Fukomys damarensis reveals rapid colonization of arid savannahs during the late Pleistocene

Abstract

The Damaraland mole-rat (Fukomys damarensis) is a cooperatively breeding rodent primarily inhabiting sandy soils of southern Africa. It has the largest distribution of all the species in the genus Fukomys, from northwestern South Africa to Zambia, and from central Namibia across to western Zimbabwe. To the north of the Zambezi River in Zambia, it is replaced by its sister species Micklem’s mole-rat (Fukomys micklemi). Despite a long history of studying the species, phylogeography of F. damarensis remains poorly understood. We analysed its intraspecific genetic structure and past population trends using mitochondrial cytochrome b sequences (published as well as acquired from museum and newly collected specimens). Also, we explored major axes of soil and climate variation among localities inhabited by this species. For comparison, we performed the same series of analyses also for F. micklemi. Within F. damarensis, we identified three major matrilineages. They were all found together in the Upper Zambezi – Okavango Delta region, where their habitat characteristics overlap widely with those of F. micklemi. However, one of the matrilineages likely underwent rapid expansion southwards to the sandy soils of Botswana, Namibia and northwestern South Africa. The expansion was tentatively dated to the second half of the last glacial, a period of increasing aridity and formation of sandy soils. This is in sharp contrast to F. micklemi, whose population had been much more stable over the last glacial cycle.