Native Rattus, Land Bridges, and the Australian Region

Abstract

A phylogenetic link between the Rattus fauna of Australia and New Guinea is indicated in two different lineages of this genus. Rattus sordidus is an Australian species and primarily is a grassland and swamp inhabitant that gained access to New Guinea and now is established there as two endemic subspecies. Rattus leucopus is a New Guinean species of the lowland tropical rain forests that also occupies comparable habitat in the Cape York Peninsula of northern Australia, where it occurs as two subspecies. Previous suggestions, that there is an evolutionary connection between R. leucopus and progenitor stock of R. fuscipes coractus of Australia, and with that of certain New Guinean species, including R. praetor , now are corroborated with craniometric evidence of phenetic similarity. The remaining species in Australia appear to have shared no immediate common ancestry with those of New Guinea and, among all Australian species, only R. leucopus appears to have colonized Australia from New Guinea. Our phylogenetic interpretation is supported by both phenetic analyses and by patterns of geographic distribution.