Metabolic rate scales disproportionally with body mass, such that the energetic cost of living is relatively lower in larger organisms. Theory emphasises the importance of fixed physical constraints on metabolic scaling, yet empirical data are lacking with which to assess how evolutionary processes (e.g. mutation, drift, selection) contribute to the observed variation in metabolic scaling across the tree of life. Using a large-scale quantitative genetic study of growth in cockroaches, we show that ontogenetic metabolic scaling is evolutionarily constrained due to an absence of additive genetic variation in juvenile metabolic rate and mass. Using a phylogenetic analysis, we also show that ontogenetic metabolic scaling is more similar among closely related species than among distant relatives, suggesting that the constraints on metabolic scaling are subject to change during lineage diversification. Our results are consistent with growing evidence that there is strong stabilising selection on combinations of mass and metabolic rate within species.

中文翻译：

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尽管物种内部存在进化限制，但代谢比例在物种之间仍存在差异

代谢率与体重成比例地成比例，因此较大生物体的能量消耗成本相对较低。理论强调固定的物理约束条件对代谢尺度的重要性，但缺乏经验数据来评估进化过程（例如突变，漂移，选择）如何影响整个生命树中代谢尺度的变化。使用蟑螂生长的大规模定量遗传研究，我们表明，由于在幼年代谢率和质量上不存在累加的遗传变异，因此个体发育的代谢缩放受进化限制。使用系统发育分析，我们还显示，亲缘关系物种之间的遗传代谢比例比远亲物种更相似，提示在谱系多样化过程中，对代谢缩放的限制可能会发生变化。我们的结果与越来越多的证据一致，即在物种内质量和代谢率的组合上有很强的稳定选择。