Thermal, metabolic, hygric and ventilatory physiology of the sandhill dunnart (Sminthopsis psammophila; Marsupialia, Dasyuridae)

Philip C. Withers*, Christine E. Cooper

*Corresponding author for this work

Research output: Contribution to journalArticle

24 Citations (Scopus)

Abstract

We present here the first physiological data for the sandhill dunnart (Sminthopsis psammophila), the second largest (35-44 g) sminthopsine dasyurid marsupial, and report torpor for this species. Their thermoneutral body temperature (34.4 degrees C), thermolability below thermoneutrality (0.062 degrees C degrees C(-1)), and mild hyperthermia above thermoneutrality (35.5 degrees C) are typical of small dunnarts, and dasyurids. Basal metabolic rate (0.80 mL O(2) g(-1) h(-1)) is as predicted from mass. Sandhill dunnarts generally conform to the Scholander-Irving model of endothermy, although metabolism increases less than expected and extrapolates to a higher than actual body temperature. Wet (0.22 mL O(2) g(-1) h(-1) C(-1)) and dry (2.8 J g(-1) h(-1) degrees C(-1)) thermal conductances were as predicted. Thermoneutral evaporative water loss (1.6 mg g(-1) h(-1)) was only 54% of expected, but this is not significantly different, and more likely reflects variability in the marsupial dataset than an adaptation. Relative water economy resembles that of other small marsupials, rodents and birds, with a point of relative economy of 18 degrees C. Respiratory ventilation closely matches metabolic rate, with minute volume increased at low ambient temperatures by increased breathing rate rather than tidal volume; oxygen extraction was constant at about 17%, except during hyperthermia above the thermoneutrality. Torpor conferred significant energetic and hygric benefits. We found no evidence of deviation from allometrically- and phylogenetically-based expectations despite the sandhill dunnart's and habitat and large (for a dunnart) body mass. (C) 2009 Elsevier Inc. All rights reserved.

Original languageEnglish
Pages (from-to)317-323
Number of pages7
JournalComparative Biochemistry and Physiology. Part A: Molecular & Integrative Physiology
Volume153
Issue number3
DOIs
Publication statusPublished - Jul 2009
Externally publishedYes

Keywords

  • Sminthopsis psammophila metabolic rate
  • BMR
  • Evaporative water loss
  • Respiratory ventilation
  • Water economy
  • Marsupial
  • NUMBAT MYRMECOBIUS-FASCIATUS
  • EVAPORATIVE WATER-LOSS
  • DAILY TORPOR
  • AMBIENT-TEMPERATURE
  • MACROPUS-GIGANTEUS
  • GRANIVOROUS BIRDS
  • ARCTIC MAMMALS
  • OXYGEN-DEMAND
  • THERMOREGULATION
  • ACCOMMODATION

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