Evolutionary Relationships of Australian Marsupials as Assessed by Albumin Immunology

Abstract

Current phylogenetic hypotheses of the relationships of Australian marsupials were tested by microcomplement fixation of albumin. The study involved antisera to albumins of 56 species, and cross- reactions to albumins of 199 species. The most notable and controversial features of the study were as follows. (1) Two major lineages are evident among the Australian marsupials- bandicoots-dasyuroids and diprotodontids; the marsupial mole represents a third lineage. (2) The honey possum Tarsipes is clearly a diprotodontid. (3) Acrobates and Distoechurus are monophyletic, but they are not burramyids; they are closely related to Tarsipes; moreover the Acrobates-Distoechurus-Tarsipes clade may be close to petaurids. (4) The New Guinean species of Antechinus are more closely related to the New Guinean Murexia than to Australian species of Antechinus. (5) The bandicoots fall into two groups-the New Guinean genera and the Australian genera; the bilby, Macrotis lagotis, is not clearly distinct from the bandicoots, and may be monophyletic with the New Guinean genera. (6) The banded hare-wallaby Lagostrophus is clearly the sister-group to all other extant macropodines, and may be monophyletic with potoroines rather than macropodines. (7) The genus Macropus may be paraphyletic. (8) The tree-kangaroos Dendrolagus may be closely related to the rock-wallabies and their allies (Petrogale, Peradorcas and Thylogale). (9) The genus Pseudocheirus (ringtail possums) is paraphyletic and its species are highly divergent at the molecular level. (10) The cuscuses (genus Phalanger) are probably a monophyletic assemblage.