Wallaroo

Abstract: Recent molecular analyses suggest that the position of bandicoots is the major difficulty in determining the root of the tree of extant marsupials. To resolve this, we analyse mitochondrial genome sequences of a bandicoot (Isoodon macrourus) and a brushtail possum (Trichosurus vulpecula) together with the previously available marsupial mitochondrial genomes, the Virginia opossum (Didelphis virginiana) and the wallaroo (Macropus robustus). Analyses of mitochondrial protein-coding and RNA genes strongly support the bandicoot as sister to the wallaroo and the brushtail possum. This result, combined with other recent molecular analyses, confirms the monophyly of Australidelphia (Australasian marsupials plus Dromiciops from South America). Further, RY coding was found to nullify AGCT coding nucleotide composition bias.

Abstract: 1 Much recent research has focused on the use of species distribution models to explore the influence(s) of environment (predominantly climate) on species' distributions A weakness of this approach is that it typically does not consider effects of biotic interactions, including competition, on species' distributions 2 Here we identify and quantify the contribution of environmental factors relative to biotic factors (interspecific competition) to the distribution and abundance of three large, wide-ranging herbivores, the antilopine wallaroo (Macropus antilopinus), common wallaroo (Macropus robustus) and eastern grey kangaroo (Macropus giganteus), across an extensive zone of sympatry in tropical northern Australia 3 To assess the importance of competition relative to habitat features, we constructed models of abundance for each species incorporating habitat only and habitat + the abundance of the other species, and compared their respective likelihoods using Akaike's information criterion We further assessed the importance of variables predicting abundance across models for each species 4 The best-supported models of antilopine wallaroo and eastern grey kangaroo abundance included both habitat and the abundance of the other species, providing evidence of interspecific competition Contrastingly, models of common wallaroo abundance were largely influenced by climate and not the abundance of other species The abundance of antilopine wallaroos was most influenced by water availability, eastern grey kangaroo abundance and the frequency of late season fires The abundance of eastern grey kangaroos was most influenced by aspects of climate, antilopine wallaroo abundance and a measure of cattle abundance 5 Our study demonstrates that where census and habitat data are available, it is possible to reveal species' interactions (and measure their relative strength and direction) between large, mobile and/or widely-distributed species for which competition is difficult to demonstrate experimentally This allows discrimination of the influences of environmental factors and species interactions on species' distributions, and should therefore improve the predictive power of species distribution models

Abstract: We generated a DNA hybridization matrix comparing eleven ‘true’ kangaroos (Macropodinae) and two outgroup marsupials, the rufous rat-kangaroo Aepyprymnas rufescens (Potoroinae) and the brush-tailed phalanger Trichosurus vulpecula (Phalangeridae). A small matrix included additional species of the genus Macropus (large kangaroos and wallabies). The results indicate that the New Guinean forest wallaby Dorcopsulus vanheurni , and the quokka Setonix brachyurus, represent successively closer sister-groups of other macropodines. The remaining taxa examined form two clades: the tree kangaroo Dendrolagus matschiei with the pademelons Thylogale and rock wallabies Petrogale , and Macropus including the swamp wallaby Wallabia bicolor . The smaller matrix of five Macropus species and Wallabia (with Dorcopsulus as an outgroup) pairs the red-necked wallaby M. rufogriseus and Parry's wallaby M. parryi , with the eastern grey kangaroo M. giganteus as their nearest relative; and associates the red kangaroo M. rufus and wallaroo M. robustus , with Wallabia as their sister-taxon. In the larger study, we found that inclusion of both outgroups provided little resolution among the macropodines, judging by jackknife and bootstrap tests. When Aepyprymnus was deleted, the Dendrolagus-Thylogale-Petrogale association obtained; with Trichosurus eliminated instead, the Wallabia-Macropus group was recovered. Only analysis of the eleven ingroup taxa by themselves gave a topology which supported both major clades. Our findings suggest that, at least for DNA hybridization studies, when ingroup taxa are separated by very short internodes experimental error in outgroup-to-ingroup distances may seriously compromise determination of ingroup affinities as well as the position of the root. We recommend that in such cases separate analyses with the outgroups sequentially eliminated and rigorous validation of the topology at each step should be conducted.