A Molecular Phylogeny of Stylodipus (Dipodidae, Mammalia): A Small Genus with a Complex History

A range-wide phylogenetic/phylogeographic study of the three-toed jerboas of the genus Stylodipus is conducted using the mitochondrial cytb gene and fragments of several nuclear genes. The genus has been believed to include three species: S. telum (W Central Asia, SE Europe), S. andrewsi (E Central Asia), and S. sungorus (Dzungar basin). Our data support the dichotomy between S. andrewsi and the other taxa forming S. telum species group. Within the latter, both mtDNA and nuclear loci indicate a species-level divergence between S. telum and the S. t. birulae lineage (Zaisan depression, NE Kazakhstan), previously considered a subspecies of S. telum and here elevated to full species. S. sungorus is recovered as a close sister group to S. birulae on the basis of nuclear data but clustered with S. telum in the mitochondrial tree. The latter taxon is the most variable and includes two closely related eastern and western sublineages, separated by the Volga-Ural sands and joined by a more divergent S. t. karelini lineage (E Kazakhstan). The observed mitonuclear discordance is hypothesized to occur due to mtDNA introgression resulting from hybridization between S. sungorus and S. t. karelini, which highlights the important role of reticulations in the evolution of Dipodidae.