Taxonomic variation in size-density relationships challenges the notion of energy equivalence

Isaac, Nick J.B. ORCID:; Storch, David; Carbone, Chris. 2011 Taxonomic variation in size-density relationships challenges the notion of energy equivalence. Biology Letters, 7 (4). 615-618.

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The relationship between body mass and abundance is a major focus for research in macroecology. The form of this relationship has been suggested to reflect the partitioning of energy among species. We revisit classical datasets to show that size-density relationships vary systematically among taxonomic groups, with most variation occurring at the order level. We use this knowledge to make a novel test of the ‘energy equivalence rule’, at the taxonomic scale appropriate for the data. We find no obvious relationship between order-specific exponents for abundance and metabolic rate, although most orders show substantially shallower (less negative) scaling than predicted by energy equivalence. This finding implies greater energy flux among larger-bodied animals, with the largest species using two orders of magnitude more energy than the smallest. Our results reject the traditional interpretation of energy equivalence as a predictive rule. However, some variation in size-density exponents is consistent with a model of geometric constraints on foraging.

Item Type: Publication - Article
Digital Object Identifier (DOI):
Programmes: CEH Topics & Objectives 2009 - 2012 > Biodiversity > BD Topic 1 - Observations, Patterns, and Predictions for Biodiversity > BD - 1.4 - Quantify and model interactions to determine impacts ...
UKCEH and CEH Sections/Science Areas: Pywell
ISSN: 1744-9561
Additional Keywords: metabolic ecology, metabolic theory, scaling, allometry, energetic equivalence, Damuth's rule, population density
NORA Subject Terms: Ecology and Environment
Date made live: 19 Oct 2011 11:34 +0 (UTC)

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