Metabolic, hygric and ventilatory physiology of the red-tailed phascogale (Phascogale calura; Marsupialia, Dasyuridae): Adaptations to aridity or arboreality?

The red-tailed phascogale is a small arboreal dasyurid marsupial that inhabits semi-arid to arid regions of Western Australia's wheat belt. Its body mass (34.7 g) is only similar to 15% of that predicted based on its phylogenetic position among other dasyuromorphs; we interpret this as an adaptation to its scansorial and semi-arid/arid lifestyle. The standard physiology of this species at a thermoneutral ambient temperature of 30 degrees C conforms to that of other dasyurid marsupials; body temperature (34.7 +/- 0.37 degrees C), basal metabolic rate (0.83 +/- 0.076 mL O-2 g(-1) h(-1)), evaporative water loss (1.68 +/- 0.218 mg H2O g(-1) h(-1)) and wet thermal conductance (3.8 +/- 0.26.1 Jg(-1) h(-1) degrees C-1) all fall within the 95% predication limits for the respective allometric relationships for other dasyurid species. Thermolability confers an energy savings at low T-a and water savings at high T-a. Torpor, observed at low T-a, was found to be more beneficial for energy savings than for water economy. The red-tailed phascogale therefore has a physiology suitable for the challenges of arid environments without any obvious requirement for adaptations to its scansorial lifestyle, other than its considerably lower-than-expected body mass. (C) 2013 Deutsche Gesellschaft fur Saugetierkunde.