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The ecological significance of torpor by mammals : dormancy, survival and life-histories
Par : Christopher Turbill, Research Institute of Wildlife Research (Vienne, Autriche)
Date : lundi 2 mai 2011 à 11h00
Lieu : IPHC, Amphi Grünewald, bâtiment 25
A wide range of mostly small mammals can drastically reduce their resting energy costs by entering bouts of torpor. Ecophysiologists have long been fascinated by the thermal physiology of torpor, but its ecological significance has been somewhat overlooked. For example, even though torpor is widespread across mammalian orders, only two of the 61 recently extinct mammals were probably heterothermic. Mammals that can use torpor to lower their energy requirements and minimise unnecessary activity seem to be less vulnerable to extinction than homeothermic species. Hibernation also is associated with a very high probability of winter survival. We argue that hibernation is a strategy not solely for energy savings but to facilitate seasonal dormancy, which allows small mammals to cease activity and avoid predation during a season when conditions are unsuitable for reproduction. Among all mammals, we find that hibernating species also have greater annual survival rates than non-hibernators, and that small hibernating species generally have longer maximum lifespans, older ages at maturity and slower rates of reproduction than similar-sized non-hibernators. Thus, like other mammalian groups with enhanced survival, small hibernating mammals have evolved traits indicative of a relatively slow life history.