An evolutionary framework for studies of hibernation and short-term torpor

Grigg, G. C. (2004). An evolutionary framework for studies of hibernation and short-term torpor. In: Brian M. Barnes and Hannah V. Carey, Biological Papers of the University of Alaska. Proceedings of: Life in the Cold. Evolution, Mechanisms, Adaptation, and Application. Life in the Cold 2004: The Twelfth International Hibernation Symposium (LITC 2004), Aboard the ms Veendam, from Vancouver, British Columbia, Canada, to Seward, Alaska, U.S.A., (131-141). 25 July-1 August 2004.


Author Grigg, G. C.
Title of paper An evolutionary framework for studies of hibernation and short-term torpor
Conference name Life in the Cold 2004: The Twelfth International Hibernation Symposium (LITC 2004)
Conference location Aboard the ms Veendam, from Vancouver, British Columbia, Canada, to Seward, Alaska, U.S.A.
Conference dates 25 July-1 August 2004
Proceedings title Biological Papers of the University of Alaska. Proceedings of: Life in the Cold. Evolution, Mechanisms, Adaptation, and Application
Place of Publication Fairbanks, Alaska
Publisher Institute of Arctic Biology, University of Alaska
Publication Year 2004
Sub-type Fully published paper
ISSN 0568-8604
Editor Brian M. Barnes
Hannah V. Carey
Volume 27
Start page 131
End page 141
Total pages 11
Collection year 2004
Language eng
Abstract/Summary Data from diverse studies endorse ideas that short term torpor and hibernation are expressions of ancient characters. In evolutionary terms, their basic mechanisms are probably plesiomorphic (= ancestral/primitive) and physiologically similar. This contrasts with the alternate view that they are apomorphic (= derived, specialized), arising independently in many taxa from homeothermic ancestry by numerous apparent convergences. This paper explores some of the implications of accepting the plesiomorphic interpretation. Hibernation is, of course, a complex phenomenon that has undergone variations and refinements in different mammalian lineages. The argument is not that hibernation in total is a plesiomorphic character, but that it is built upon fundamental processes that are. Taking this view provides a framework for research that emphasizes the value of comparative studies, particularly of reptiles and birds. Studies of reptiles, for example, might unravel the mystery about periodic arousals. A plesiomorphic framework also explains the most extreme examples of hibernation as derived specializations from ancestry in which heterothermy is more about energy management than escape from cold. It cautions against using low body temperature (Tb) alone to diagnose torpor, emphasizes the need to distinguish between constitutional eurythermy (plesiomorphic) and constitutional stenothermy (apomorphic), and leads to a parsimonious theory about the evolution of endothermy. The paper proposes that brown adipose tissue (BAT) is apomorphic within eutheria and highlights the conundrum posed by the occurrence of both nonshivering thermogenesis (NST) and rapid arousal from hibernation in noneutherian mammals that lack BAT and uncoupling protein 1 (UCP1). It endorses the likely existence of a different, ancient and widespread mechanism for regulatory NST in mammals.
Subjects E1
270604 Comparative Physiology
780105 Biological sciences
Keyword Whole animal physiology
Temperature relationships
Dormancy
Q-Index Code E1
Additional Notes Presented during "Hibernation and Torpor: Ecology, Evolution and Behavior" under the original title "Are torpor and hibernation plesiomorphic?: Implications for hibernation and the evolution of endothermy"

 
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Created: Thu, 23 Aug 2007, 19:50:06 EST