Dasyurids are the dominant terrestrial carnivores of Australia, occupying a diverse array of habitats such as aridlands, forest, and alpine heath. They are small to medium sized mammals, ranging from the tiny Pilbara ningaui (209 g) to the dog-sized Tasmanian devil (6-8 kg). With approximately 51 species in 17 genera, the family Dasyuridae constitutes one of three major lineages of Australasian marsupials. Attempts to understand the evolutionary relationships among dasyurids date from the early 20th century, but these efforts could only reveal the broadest outlines of phylogeny. In recent years, comparative study of molecular genetic variation among dasyurids has shed much light on relationships within the family, but a detailed and well-resolved branching order for genera has not been established. This lack of phylogenetic resolution has hampered efforts to understand the historical biogeography of dasyurids, particularly the origins of New Guinean endemics. In this study, DNA sequence variation in the mitochondrial cytochrome-b gene will be assayed for representatives of all dasyurid genera. Cytochrome-b, a key component in cellular energy production, is a relatively small (ca. 400 residues) and simple molecule. Patterns of DNA variation in cytochrome-b across the range of divergence times represented by dasyurids will allow construction of a simple model of how the gene evolves. The value of such a model for estimating phylogeny is a key issue in modern molecular systematics. The data and model together will provide an interesting means of comparing several current and conceptually distinct methods of phylogenetic inference. Final results should provide a clearer picture of dasyurid relationships, as well as a better understanding of cytochrome-b evolution and molecular phylogenetics.
