Growth and Mortality as Causes of Variation in Metabolic Scaling Among Taxa and Taxonomic Levels
Growth and Mortality as Causes of Variation in Metabolic Scaling Among Taxa and Taxonomic Levels
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生长和死亡率是类群和分类水平之间代谢规模变化的原因
DOI：
10.1093/icb/icac038
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发表时间：
2022
影响因子：
2.6
通讯作者：
Norin, Tommy
中科院分区：
文献类型：
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作者：
Norin, Tommy
代谢率（MR）通常与体重（BM）不成比例地变化（缩放），如MR =aBMb，其中是一个归一化常数，是反映这种变化有多陡的缩放指数。这种比例关系是生物学的基础，但一个多世纪的研究对b的价值，以及为什么它在分类群和分类水平上有所不同，几乎没有达成共识。通过分析已发表的鱼类数据，并采用基于个体的代谢缩放方法，我表明，在自然限制食物供应的情况下，鱼类的生长变化可以解释褐鳟（Salmo trutta）的个体（个体发生）标准（维持）代谢率（SMR）的变化，最快的养殖者具有最陡峭的代谢缩放（b≈1）。此外，我表明个体内的差异可能比以前在不同个体或不同物种的研究中所假设的要大得多，单个褐鳟的SMR从-1到1。一些个体的SMR呈负缩放是由于在食物有限的环境中代谢率降低，可能保持正增长。这导致个体内的平均SMR显著低于跨个体（“静态”）b，另一种物种（Tautogolabrus adspersus）也存在这种差异。有趣的是，在同一条鱼的最大（活性）代谢率（MMR）中，个体间SMR的个体遗传差异并不存在，这表明这两个关键代谢性状（SMR和MMR）可以相互独立地扩展。我还表明，134种鱼类的SMR的跨物种（“进化”）比褐鳟和康纳鱼的平均个体遗传明显更陡峭（接近1）。基于这些有趣的发现，我假设进化和静态代谢鳞片可以系统地不同于个体发生的鳞片，并且鱼类的进化鳞片比个体发生的鳞片更陡峭，这是生长迅速的个体在生命早期具有陡峭的代谢鳞片（b≈1）的自然选择的副产品，在那里鱼类的尺寸选择性死亡率很高。我通过显示SMR倾向于随着分类群内鱼类幼虫的自然死亡率的增加而增加来支持这一观点。
Metabolic rate (MR) usually changes (scales) out of proportion to body mass (BM) as MR =aBMb, whereais a normalisation constant andbis the scaling exponent that reflects how steep this change is. This scaling relationship is fundamental to biology, but over a century of research has provided little consensus on the value ofb, and why it appears to vary among taxa and taxonomic levels. By analysing published data on fish and taking an individual-based approach to metabolic scaling, I show that variation in growth of fish under naturally restricted food availability can explain variation in within-individual (ontogenetic)bfor standard (maintenance) metabolic rate (SMR) of brown trout (Salmo trutta), with the fastest growers having the steepest metabolic scaling (b≈ 1). Moreover, I show that within-individualbcan vary much more widely than previously assumed from work on different individuals or different species, from –1 to 1 for SMR among individual brown trout. The negative scaling of SMR for some individuals was caused by reductions in metabolic rate in a food limited environment, likely to maintain positive growth. This resulted in a mean within-individualbfor SMR that was significantly lower than the across-individual (“static”)b, a difference that also existed for another species, cunner (Tautogolabrus adspersus). Interestingly, the wide variation in ontogeneticbfor SMR among individual brown trout did not exist for maximum (active) metabolic rate (MMR) of the same fish, showing that these two key metabolic traits (SMR and MMR) can scale independently of one another. I also show that across-species (“evolutionary”)bfor SMR of 134 fishes is significantly steeper (bapproaching 1) than the mean ontogeneticbfor the brown trout and cunner. Based on these interesting findings, I hypothesise that evolutionary and static metabolic scaling can be systematically different from ontogenetic scaling, and that the steeper evolutionary than ontogenetic scaling for fishes arises as a by-product of natural selection for fast-growing individuals with steep metabolic scaling (b≈ 1) early in life, where size-selective mortality is high for fishes. I support this by showing thatbfor SMR tends to increase with natural mortality rates of fish larvae within taxa.