Allometry of thermal variables in mammals: consequences of body size and phylogeny

Author(s)
Riek, Alexander
Geiser, Fritz
Publication Date
2013
Abstract
A large number of analyses have examined how basal metabolic rate (BMR) is affected by body mass in mammals. By contrast, the critical ambient temperatures that define the thermo-neutral zone (TNZ), in which BMR is measured, have received much less attention. We provide the first phylogenetic analyses on scaling of lower and upper critical temperatures and the breadth of the TNZ in 204 mammal species from diverse orders. The phylogenetic signal of thermal variables was strong for all variables analysed. Most allometric relationships between thermal variables and body mass were significant and regressions using phylogenetic analyses fitted the data better than conventional regressions. Allometric exponents for all mammals were 0.19 for the lower critical temperature (expressed as body temperature - lower critical temperature), −0.027 for the upper critical temperature, and 0.17 for the breadth of TNZ. The small exponents for the breadth of the TNZ compared to the large exponents for BMR suggest that BMR per se affects the influence of body mass on TNZ only marginally. However, the breadth of the TNZ is also related to the apparent thermal conductance and it is therefore possible that BMR at different body masses is a function of both the heat exchange in the TNZ and that encountered below and above the TNZ to permit effective homeothermic thermoregulation.
Citation
Biological Reviews, 88(3), p. 564-572
ISSN
1469-185X
1464-7931
Link
Publisher
Wiley-Blackwell Publishing Ltd
Title
Allometry of thermal variables in mammals: consequences of body size and phylogeny
Type of document
Journal Article
Entity Type
Publication

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