Skeletal variation and taxonomic boundaries among mainland and island populations of the common treeshrew (Mammalia: Scandentia: Tupaiidae)

Treeshrews (order Scandentia) include 23 currently recognized species of small-bodied mammals from South and Southeast Asia. The taxonomy of the common treeshrew, Tupaia glis, which inhabits the Malay Peninsula south of the Isthmus of Kra, as well as a variety of offshore islands, has an extremely complicated history resulting from its wide distribution and subtly variable pelage. In our ongoing investigation of species boundaries in Tupaia, we compared island and mainland populations of T. glis using multivariate analyses. Specifically, we compared the skull and hand morphology of 13 island populations, most of which have been recognized as separate species or subspecies, to that of the mainland population. Island populations generally average smaller body size than those on the mainland, but none of the island populations are sufficiently distinct from the mainland population to warrant species recognition. This has important conservation implications for this widespread and morphologically variable species. It also highlights the potential role that ecogeographic explanations can play in understanding intraspecific variation, a role that should be considered in taxonomic studies and investigated further in T. glis and other treeshrews.