Phylogenetic relationships of elephant-shrews (Afrotheria, Macroscelididae)

Elephant-shrews or sengis (Macroscelidea, Afrotheria) are grouped into two subfamilies, Rhynchocyoninae with a single genus and four species, and Macroscelidinae represented by three genera and 13 species. Our current understanding of the evolutionary relationships within this group is largely based on a molecular phylogeny that suffers from incomplete species representation. We present the first complete phylogeny (with the exception of the recently described East African Rhynchocyon udzungwensis) for Macroscelidea based on mitochondrial and nuclear markers. Novel cytogenetic characters as well as previously described allozyme variation and various morphological features are evaluated and mapped to the molecular topology. Our analyses indicate that Elephantulus is paraphyletic, and that Petrodromus and Macroscelides should be subsumed in Elephantulus. A relaxed Bayesian dating approach supports the hypothesis that an arid-adapted Macroscelidinae lineage dispersed from east Africa at ∼11.5MYA via an African arid corridor to south-western Africa. The timing of speciation within the east African Rhynchocyoninae (8-10MYA) is coincidental with the diversification of some other forest specialists. In turn, divergence within the Macroscelidinae coincides with major aridification events across Africa.