Towards an understanding of marsupial interchange between Australia and New Guinea
Abstract
A review of the geology, palaeontology, genetic, and morphology studies indicates that during the mid-Miocene to Pliocene, New Guinea consisted of four island Blocks (Vogelkop, Maokop, Central, and Southeastern). The initial dispersal of marsupials from Australia was into the Vogelkop Block. The ancestors of at least six genera (Dactylonax, Microperorytes, Myoictis Pseudochirops, Spilocuscus, Tous) and three species (Dendrolagus inustus, Dendrolagus ursinus, Dorcopsis muelleri) of endemic New Guinean marsupials are likely to have reached New Guinea via this route. The Dendrolagus dorianus complex and two marsupial genera (Dactylopsila and Phalanger) may have reached New Guinea via the Maokop Block, with Thylogale arriving either via the Maokop or Southeastern Block. Four species, or species complexes, of marsupials in the genera Dendrolagus, Dorcopsis, Murexia, and Peroryctes may have arrived via the Southeastern Block. The Central Block lacks evidence of Tertiary marsupial transfers from Australia, and may not have been connected with Australia prior to its incorporation into New Guinea. Two possum taxa (Tous ayamaruensis and Dactylonax kambuayai), which occur in the Vogelkop lowlands, are hypothesized to have been restricted from expansion into the slopes of the Central Cordillera by a combination of tectonics and ecological barriers. A further two species pairs/triplets (Dactylonax palpator/ernstmayri, Pseudochirops albertisii/coronatus/cupreus) provide evidence of a highly unusual pattern of dispersal within New Guinea, whereby the high-elevation members of each pair have dispersed and speciated, while the mid-elevation members have not. Finally, marsupial distributions indicate that in the early Pleistocene a contiguous mountain range, named here the Northern Cordillera, extended from Vogelkop to the Torricelli Mountains.
