Metabolic rate and body temperature reduction during hibernation and daily torpor.
- F. Geiser
- BiologyAnnual Review of Physiology
- 11 February 2004
The comparative analysis provided here suggests that MR reduction depends on patterns of torpor used, the state of tor porpor, and body mass, which in turn affects metabolic inhibition and energy conservation.
Hibernation versus Daily Torpor in Mammals and Birds: Physiological Variables and Classification of Torpor Patterns
Comparisons of several physiological variables appear to justify a distinction between the two torpor patterns, but of all variables tested, only the frequency distributions of maximum torpor bout duration and the minimum V̇o2 showed a clear gap between daily heterotherms and hibernators.
Daily torpor and hibernation in birds and mammals
The analysis strongly supports the view that hibernators and daily heterotherms are functionally distinct groups that probably have been subject to disruptive selection.
Reduction of metabolism during hibernation and daily torpor in mammals and birds: temperature effect or physiological inhibition?
- F. Geiser
- BiologyJournal of Comparative Physiology □ B
- 2004
Findings show that the reduction in metabolism during torpor of daily heterotherms and large hibernators can be explained largely by temperature effects, whereas a metabolic inhibition in addition to temperature effects may be used by small hibernator to reduce energy expenditure during torpora.
Periodic arousals in hibernating mammals: is evaporative water loss involved?
- Donald W. Thomas, F. Geiser
- Environmental Science
- 1 October 1997
It is suggested that torpor bout duration may be influenced by EWL, indicating that animals may need to obtain free water when they arouse and an analysis of the structural and temperature characteristics of ground squirrel hibernacula suggests that they may function as a biological condensing tower.
EVOLUTION OF DAILY TORPOR AND HIBERNATION IN BIRDS AND MAMMALS: IMPORTANCE OF BODY SIZE
- F. Geiser
- BiologyClinical and Experimental Pharmacology and…
- 1 September 1998
1. The evolution of hibernation and daily torpor in mammals and birds remains a controversial subject. The original view was that use of torpor reflects a primitive thermoregulation, as it occurs in…
THE TEMPORAL ORGANIZATION OF DAILY TORPOR AND HIBERNATION: CIRCADIAN AND CIRCANNUAL RHYTHMS
- G. Körtner, F. Geiser
- Environmental ScienceChronobiology International
- 1 January 2000
It is reviewed whether circadian and circannual rhythms, important in the timing of biological events in active animals, also play an important role during torpor when Tb is reduced substantially and may even fall below 0°C, and there is little evidence it is significantly affected by low Tb.
Torpor Duration in Relation to Temperature and Metabolism in Hibernating Ground Squirrels
It is concluded that T_{b} per se also contributes, along with metabolism, to determining the length of torpor bouts, and the hypothesis that arousal is determined by accumulation of metabolites during torpor is confirmed.
Torpor, thermal biology, and energetics in Australian long-eared bats (Nyctophilus)
- F. Geiser, R. Brigham
- Environmental Science, BiologyJournal of Comparative Physiology □ B
- 1 March 2000
The study suggests that Australian Nyctophilus bats have a low basal metabolic rate and that their patterns of torpor are similar to those measured in bats from the northern hemisphere.
Deep, prolonged torpor by pregnant, free-ranging bats
- C. Willis, R. Brigham, F. Geiser
- BiologyDie Naturwissenschaften
- 3 February 2006
Observations imply a fitness advantage of torpor in addition to energy conservation because reduced foetal growth rate could delay parturition until conditions are more favourable for lactation and neonatal survival.
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