With Christopher Parkinson, I explored evolutionary relationships at various taxonomic levels within they rodent family Sciuridae, one of the largest and most widely dispersed families of mammals. The broad-scale analysis (114 species in 21 genera) revealed substantial conflicts with taxonomic assignments at the subfamily, tribe, genus and species levels. The fine-scale analysis focused on African ground squirrels of the genus Xerus. Relationships among Xerus species suggest that the genus originated in northern Africa, dispersed to southern Africa through an ‘arid corridor’ running from the Horn of Africa to the Cape region, and subsequently diverged into the two southern African species (X. inauris and X. princeps). Xerus inauris includes three major clades, which probably diverged because of climate-driven allopatric fragmentation.
Herron, M. D., J. M. Waterman, and C. L. Parkinson. 2005. Phylogeny and historical biogeography of African ground squirrels: the role of climate change in the evolution of Xerus. Molecular Ecology 14(9):2773-2788. (pdf)
Herron, M. D., T. A. Castoe, and C. L. Parkinson. 2004. Sciurid phylogeny and the paraphyly of Holarctic ground squirrels (Spermophilus). Molecular Phylogenetics and Evolution 31(3):1015-1030. (pdf)