White Craig R, Cassey Phillip, Blackburn Tim M
School of Biosciences, The University of Birmingham, Edgbaston, Birmingham, B15 2TT, UK.
Ecology. 2007 Feb;88(2):315-23. doi: 10.1890/05-1883.
The debate about the value of the allometric scaling exponent (b) relating metabolic rate to body mass (metabolic rate = a x mass(b)) 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.
关于将代谢率与体重相关联的异速生长比例指数（b）（代谢率 = a × 体重^b）的价值的争论仍在继续，支持和反对3/4幂比例定律的已发表证据不断积累。然而，这场争论常常围绕着营养物质分配网络的最新模型预测的3/4幂指数与欧几里得表面积与体积关系预测的2/3指数之间的二分法区别展开。这种方法没有考虑到不存在单一“真实”指数的可能性。在本研究中，我们对127个种间异速生长指数进行了荟萃分析，以确定是否存在通用的代谢异速生长关系，或者不同分类群之间或代谢状态之间是否存在系统差异。该分析表明，体重对代谢率的效应大小存在显著异质性，并且平均而言，体重对代谢率的影响在恒温动物中比变温动物更强。在变温动物和恒温动物之间以及代谢状态（如休息、野外和运动）之间也发现了比例指数的显著差异，这一结果适用于通过普通最小二乘法、主轴缩减法和系统发育校正回归模型估计的b值。对单一指数模型缺乏支持表明不存在通用的代谢异速生长关系，这对任何仅预测单一b值的模型构成了重大挑战。
