McKechnie Andrew E, Freckleton Robert P, Jetz Walter
DST/NRF Centre of Excellence at the Percy FitzPatrick Institute, School of Animal, Plant and Environmental Sciences, University of the Witwatersrand Private Bag 3, Wits 2050, South Africa.
Proc Biol Sci. 2006 Apr 22;273(1589):931-7. doi: 10.1098/rspb.2005.3415.
Many birds exhibit short-term, reversible adjustments in basal metabolic rate (BMR), but the overall contribution of phenotypic plasticity to avian metabolic diversity remains unclear. The available BMR data include estimates from birds living in natural environments and captive-raised birds in more homogenous, artificial environments. All previous analyses of interspecific variation in BMR have pooled these data. We hypothesized that phenotypic plasticity is an important contributor to interspecific variation in avian BMR, and that captive-raised populations exhibit general differences in BMR compared to wild-caught populations. We tested this hypothesis by fitting general linear models to BMR data for 231 bird species, using the generalized least-squares approach to correct for phylogenetic relatedness when necessary. The scaling exponent relating BMR to body mass in captive-raised birds (0.670) was significantly shallower than in wild-caught birds (0.744). The differences in metabolic scaling between captive-raised and wild-caught birds persisted when migratory tendency and habitat aridity were controlled for. Our results reveal that phenotypic plasticity is a major contributor to avian interspecific metabolic variation. The finding that metabolic scaling in birds is partly determined by environmental factors provides further support for models that predict variation in scaling exponents, such as the allometric cascade model.
许多鸟类在基础代谢率（BMR）方面表现出短期的、可逆的调整，但表型可塑性对鸟类代谢多样性的总体贡献仍不明确。现有的基础代谢率数据包括来自生活在自然环境中的鸟类以及在更同质的人工环境中圈养繁殖的鸟类的估计值。此前所有对基础代谢率种间变异的分析都将这些数据合并在一起。我们假设表型可塑性是鸟类基础代谢率种间变异的一个重要因素，并且圈养繁殖的种群与野生捕获的种群相比，在基础代谢率方面存在一般差异。我们通过对231种鸟类的基础代谢率数据拟合一般线性模型来检验这一假设，必要时使用广义最小二乘法来校正系统发育相关性。圈养繁殖鸟类中基础代谢率与体重的标度指数（0.670）明显比野生捕获鸟类（0.744）更平缓。当控制迁徙倾向和栖息地干旱程度时，圈养繁殖鸟类和野生捕获鸟类在代谢标度上的差异依然存在。我们的结果表明，表型可塑性是鸟类种间代谢变异的一个主要因素。鸟类代谢标度部分由环境因素决定这一发现，为预测标度指数变化的模型，如异速生长级联模型，提供了进一步支持。
