Search Results (6)

Morphometric cardiac reference values are reported for macropods and koalas (Phascolarctos cinereus). Body weight (BW), heart weight (HW), left ventricle (LV) wall, interventricular septum (S), right ventricle (RV) wall thickness, and LV+S and RV weights were measured at postmortem examination of 48 macropods and 32 koalas that had no evidence of cardiovascular disease. The HW/BW% (0.43–0.96%) and (LV+S)/RV (2.80–4.22) for macropods were comparable to domestic species. In koalas, the HW/BW% (0.25–0.51%) was lower, and the (LV+S)/RV (3.06–5.41) ranged higher than in macropods and domestic species. The LV:RV of koalas (1.0–10.8) was more variable than in macropods (1.17–4.27). Two macropods with cardiac disease were assessed on postmortem examination against the generated reference values. An adult male common wallaroo (Osphranter robustus) was found dead with copious serous peritoneal effusion, chronic passive hepatic congestion with centrilobular fibrosis, and dilation of the RV, while the LV:RV was elevated, supportive of RV thinning. A 21-year-old female zoo-housed Matschie’s tree kangaroo (Dendrolagus matschiei) had a flaccid thin-walled RV, LV cardiomyocyte hypertrophy, interstitial myocardial fibrosis and myofiber degeneration, pulmonary oedema, and serous pericardial effusion. The (LV+S)/RV and LV:RV were elevated and RV:S decreased, supporting left hypertrophic cardiomyopathy. Species-specific reference values presented in this study facilitate objective and improved postmortem cardiac assessment in macropods and koalas. Full article

Monitoring ground layer biomass, and therefore forage availability, is important for managing large, vertebrate herbivore populations for conservation. Remote sensing allows for frequent observations over broad spatial scales, capturing changes in biomass over the landscape and through time. In this study, we explored different satellite-derived vegetation indices (VIs) for their utility in estimating understorey biomass in semi-arid woodlands of south-eastern Australia. Relationships between VIs and understorey biomass data have not been established in these particular semi-arid communities. Managers want to use forage availability to inform cull targets for western grey kangaroos (Macropus fuliginosus), to minimise the risk that browsing poses to regeneration in threatened woodland communities when grass biomass is low. We attempted to develop relationships between VIs and understorey biomass data collected over seven seasons across open and wooded vegetation types. Generalised Linear Mixed Models (GLMMs) were used to describe relationships between understorey biomass and VIs. Total understorey biomass (live and dead, all growth forms) was best described using the Tasselled Cap (TC) greenness index. The combined TC brightness and Modified Soil Adjusted Vegetation Index (MSAVI) ranked best for live understorey biomass (all growth forms), and grass (live and dead) biomass was best described by a combination of TC brightness and greenness indices. Models performed best for grass biomass, explaining 70% of variation in external validation when predicting to the same sites in a new season. However, we found empirical relationships were not transferrable to data collected from new sites. Including other variables (soil moisture, tree cover, and dominant understorey growth form) improved model performance when predicting to new sites. Anticipating a drop in forage availability is critical for the management of grazing pressure for woodland regeneration, however, predicting understorey biomass through space and time is a challenge. Whilst remotely sensed VIs are promising as an easily-available source of vegetation information, additional landscape-scale data are required before they can be considered a cost-efficient method of understorey biomass estimation in this semi-arid landscape. Full article

Goodfellow’s tree kangaroos (Dendrolagus goodfellowi) are an endangered, arboreal macropod native to the lower, mid-montane rainforests of Papua New Guinea. Despite a number of holders keeping D. goodfellowi in zoos across the world, there is a lack of recent published work on this species. Here, we present daytime activity budgets, document height use and provide husbandry information for two Goodfellow’s tree kangaroos (Dendrolagus goodfellowi buergersi) housed at Chester Zoo, UK. Throughout the observation period, both individuals spent the majority of their time resting within the environment but also spent time engaging in vigilance, travel and feeding behaviour. Additionally, despite the age and sex differences of the study individuals, both animals used the highest height level in the indoor habitat most frequently. We aim to share our information and encourage knowledge transfer with other holders, to both increase understanding and promote evidence-based management of this species. Full article

Regression analysis using line equations has been broadly applied in studying the evolutionary relationship between the response trait and its covariates. However, the characteristics among closely related species in nature present abundant diversities where the nonlinear relationship between traits have been frequently observed. By treating the evolution of quantitative traits along a phylogenetic tree as a set of continuous stochastic variables, statistical models for describing the dynamics of the optimum of the response trait and its covariates are built herein. Analytical representations for the response trait variables, as well as their optima among a group of related species, are derived. Due to the models’ lack of tractable likelihood, a procedure that implements the Approximate Bayesian Computation (ABC) technique is applied for statistical inference. Simulation results show that the new models perform well where the posterior means of the parameters are close to the true parameters. Empirical analysis supports the new models when analyzing the trait relationship among kangaroo species. Full article

A hybrid origin for a conservation listed taxon will influence its status and management options. Here, we investigate the genetic origins of a nationally endangered listed taxon—Eucalyptus paludicola—a tree that is restricted to the Fleurieu Peninsula and Kangaroo Island of South Australia. Since its description in 1995, there have been suggestions that this taxon may potentially be a stable hybrid species. Using a high throughput sequencing approach, we developed a panel of polymorphic loci that were screened across E. paludicola and its putative parental species E. cosmophylla and E. ovata. Bayesian clustering of the genotype data identified separate groups comprising E. ovata and E. cosmophylla while E. paludicola individuals were admixed between these two, consistent with a hybrid origin. Hybrid class assignment tests indicate that the majority of E. paludicola individuals (~70%) are F₁ hybrids with a low incidence of backcrossing. Most of the post-F₁ hybrids were associated with revegetation sites suggesting they may be maladapted and rarely reach maturity under natural conditions. These data support the hypothesis that E. paludicola is a transient hybrid entity rather than a distinct hybrid species. We briefly discuss the conservation implications of our findings. Full article

Infection with the larval stage of the cestode, Echinococcus granulosus sensu lato (s.l.), causes hydatid disease (hydatidosis) in a range of hosts, including macropods and other marsupials, cattle, and humans. Wild macropods are an important sylvatic reservoir for the life cycle of E. granulosus (s.l.) in Australia, and so provide a conduit for transmission of hydatid disease to domestic animals and humans. Two Lumholtz’s tree-kangaroos (Dendrolagus lumholtzi) from the Atherton Tablelands of Far North Queensland were recently found to have hydatid cysts in both liver and lung tissues. Tree-kangaroos may travel across the ground between patches of forest but are primarily arboreal leaf-eating macropods. The finding of hydatid cysts in an arboreal folivore may indicate that the area has a high level of contamination with eggs of E. granulosus (s.l.). This finding may be of significance to human health as well as indicating the need for further investigation into the prevalence of hydatid disease in domestic stock, wildlife and humans living in this rapidly urbanizing region. Full article