Data from: Cool echidnas survive the fire

Fires have occurred throughout history, including those associated with
the meteoroid impact at the Cretaceous-Palaeogene (K-Pg) boundary that
eliminated many vertebrate species. To evaluate the recent hypothesis that
the survival of the K-Pg fires by ancestral mammals was dependent on their
ability to use energy-conserving torpor, we studied body temperature
fluctuations and activity of an egg-laying mammal, the echidna
(Tachyglossus aculeatus), often considered to be a ‘living fossil’,
before, during and after a prescribed burn. All but one study animal
survived the fire in the prescribed burn area and echidnas remained
inactive during the day(s) following the fire and substantially reduced
body temperature during bouts of torpor. For weeks after the fire, all
individuals remained in their original territories and compensated for
changes in their habitat with a decrease in mean body temperature and
activity. Our data suggest that heterothermy enables mammals to outlast
the conditions during and after a fire by reducing energy expenditure,
permitting periods of extended inactivity. Therefore, torpor facilitates
survival in a fire-scorched landscape and consequently may have been of
functional significance for mammalian survival at the K-Pg boundary.

火灾在历史上屡见不鲜，其中包括与白垩纪-古近纪（K-Pg）边界陨石撞击相关的火灾——该事件导致众多脊椎动物物种灭绝。为验证近期的假说（即哺乳动物祖先能在K-Pg火灾中存活，依赖于其运用节能蛰伏（torpor）的能力），我们研究了一种产卵哺乳动物针鼹（Tachyglossus aculeatus）（常被视为“活化石”）在计划烧除（prescribed burn）前、中、后的体温波动与活动情况。除一只个体外，所有研究动物均在计划烧除区域的火灾中存活；火灾后的数日内，针鼹保持不活跃状态，且在蛰伏期间体温显著下降。火灾后数周，所有个体均留居原领地，并通过降低平均体温与活动水平来适应栖息地的变化。我们的数据表明，异温性（heterothermy）使哺乳动物能够通过减少能量消耗、维持长期不活跃状态，从而挺过火灾期间及灾后的环境。因此，蛰伏有助于在火灾烧焦的生境中存活，进而可能对K-Pg边界时期哺乳动物的存续具有功能性意义。