Multilocus phylogeny of East African gerbils (Rodentia, Gerbilliscus) illuminates the history of the Somali‐Masai savanna

Abstract

AbstractAimThe rodent genus Gerbilliscus is widespread in savannas throughout sub‐Saharan Africa. The eastern clade comprises four species with distributions centred in the Somali‐Masai biogeographical region of East Africa. We investigated the genetic diversity of the group with a view to illuminating the historical (Plio‐Pleistocene) processes that formed contemporary biota of the understudied Somali‐Masai region.LocationSomali‐Masai savanna, East Africa.MethodsWe performed multilocus genetic analyses of 240 samples from 112 localities, combining genotyping of recently collected samples (N = 145), 454‐pyrosequencing of museum material (N = 34) and published sequences (N = 61). We used Bayesian and maximum likelihood approaches for phylogenetic reconstructions, and coalescent‐based methods to delimit species. We also estimated divergence times and modelled recent and past distributions to reconstruct the major evolutionary influences in the Somali‐Masai region during the Plio‐Pleistocene.ResultsGenetic analyses provided evidence for six lineages, possibly corresponding to distinct species. The two main species groups (with two and four putative species, respectively) have overlapping distributions, but species within each group are distributed parapatrically. The origin of the eastern clade dates back to the Pliocene, while individual species diverged in the Pleistocene. The distribution of genetic diversity and ecological niche modelling point to the importance of the Rift Valley and the presence of unsuitable xeric habitats in the allopatric diversification of Gerbilliscus in the Somali‐Masai savanna within the last 5 Myr.ConclusionsThis is the first detailed phylo(bio‐)geographical study of animals with predominant distribution in the Somali‐Masai region. It revealed currently underestimated diversity of eastern clade of Gerbilliscus and proposed a scenario of its evolution during Plio‐Pleistocene. Conspicuous genetic structure of these taxa can be now used to test detailed phylogeographical hypotheses related to Plio‐Pleistocene history of gerbils and, to some extent, also biota of Somali‐Masai bioregion in general.