Allometric exponents do not support a universal metabolic allometry

White, Craig R., Cassey, Phillip and Blackburn, Tim M. (2007) Allometric exponents do not support a universal metabolic allometry. Ecology, 88 2: 315-323.


Author White, Craig R.
Cassey, Phillip
Blackburn, Tim M.
Title Allometric exponents do not support a universal metabolic allometry
Journal name Ecology   Check publisher's open access policy
ISSN 0012-9658
Publication date 2007-02
Sub-type Article (original research)
DOI 10.1890/05-1883
Volume 88
Issue 2
Start page 315
End page 323
Total pages 9
Place of publication Washington, D.C.
Publisher Ecological Society of America.
Language eng
Subject 0602 Ecology
Abstract The debate about the value of the allometric scaling exponent (b) relating metabolic rate to body mass (metabolic rate = a × massb) is ongoing, with published evidence both for and against a 3/4-power scaling law continuing to accumulate. However, this debate often revolves around a dichotomous distinction between the 3/4-power exponent predicted by recent models of nutrient distribution networks and a 2/3 exponent predicted by Euclidean surface-area-to-volume considerations. Such an approach does not allow for the possibility that there is no single “true” exponent. In the present study, we conduct a meta-analysis of 127 interspecific allometric exponents to determine whether there is a universal metabolic allometry or if there are systematic differences between taxa or between metabolic states. This analysis shows that the effect size of mass on metabolic rate is significantly heterogeneous and that, on average, the effect of mass on metabolic rate is stronger for endotherms than for ectotherms. Significant differences between scaling exponents were also identified between ectotherms and endotherms, as well as between metabolic states (e.g., rest, field, and exercise), a result that applies to b values estimated by ordinary least squares, reduced major axis, and phylogenetically correct regression models. The lack of support for a single exponent model suggests that there is no universal metabolic allometry and represents a significant challenge to any model that predicts only a single value of b.
Formatted abstract The debate about the value of the allometric scaling exponent (b) relating metabolic rate to body mass (metabolic rate = a × massb) is ongoing, with published evidence both for and against a 3/4-power scaling law continuing to accumulate. However, this debate often revolves around a dichotomous distinction between the 3/4-power exponent predicted by recent models of nutrient distribution networks and a 2/3 exponent predicted by Euclidean surface-area-to-volume considerations. Such an approach does not allow for the possibility that there is no single “true” exponent. In the present study, we conduct a meta-analysis of 127 interspecific allometric exponents to determine whether there is a universal metabolic allometry or if there are systematic differences between taxa or between metabolic states. This analysis shows that the effect size of mass on metabolic rate is significantly heterogeneous and that, on average, the effect of mass on metabolic rate is stronger for endotherms than for ectotherms. Significant differences between scaling exponents were also identified between ectotherms and endotherms, as well as between metabolic states (e.g., rest, field, and exercise), a result that applies to b values estimated by ordinary least squares, reduced major axis, and phylogenetically correct regression models. The lack of support for a single exponent model suggests that there is no universal metabolic allometry and represents a significant challenge to any model that predicts only a single value of b.
Keyword allometry
metabolic rate
quarter-power
scaling
Q-Index Code C1

Document type: Journal Article
Sub-type: Article (original research)
Collections: Excellence in Research Australia (ERA) - Collection
School of Agriculture and Food Sciences
 
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