Torpor in marsupials: recent advances
We report new findings about torpor in marsupials with regard to three energy-demanding processes: (i) development and growth, (ii) reproduction, and (iii) rewarming. Young marsupials use torpor extensively after they develop endothermy, and torpor is generally deeper and longer than in the same individuals when they reach adult size. Adult marsupials also employ torpor during pregnancy and/or lactation to reduce energy expenditure and perhaps to store fat for later use. Moreover, to enhance the energy-conserving potential of torpor, desert marsupials bask during arousal to minimise energy costs of rewarming. We show that the functions of torpor extend beyond merely reducing energy expenditure during food shortages and that torpor can save substantial amounts of energy even during the rewarming process.