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bioRxiv · 10.1101/2021.03.29.437465

Fast ontogenetic growth drives steep evolutionary scaling of metabolic rate

Norin, T.
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Abstract

Metabolic rate (MR) changes with body mass (BM) as MR = aBMb, where a is a normalisation constant (log-log intercept) and b the scaling exponent (log-log slope). This scaling relationship is fundamental to biology and widely applied, yet a century of research has provided little consensus on why and how steeply metabolic rate scales with body mass. I here show that ontogenetic (within-individual) b can be strongly and positively related to growth rates of juvenile fish when food availability is naturally restricted, with fast growing individuals having steep and near-isometric metabolic scaling (b {approx} 1). I suggest that the steep evolutionary (among-species) scaling also found for fishes (b also approaching 1) is a by-product of natural selection for these fast growing individuals early in ontogeny, and that a weaker relationship between metabolic scaling and growth later in life causes variation in b at lower taxonomic levels (within orders or species). I support these ideas by showing that b within fish orders is linked to natural mortality rates of fish larvae.

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Norin, T.. 2021-03-30. Fast ontogenetic growth drives steep evolutionary scaling of metabolic rate. https://doi.org/10.1101/2021.03.29.437465

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