Present address: School of Life Sciences, Arizona State University, Box 874501, Tempe, AZ 885287-4501, USA
Scaling of insect metabolic rate is inconsistent with the nutrient supply network model
Article first published online: 29 JAN 2007
Volume 21, Issue 2, pages 282–290, April 2007
How to Cite
CHOWN, S. L., MARAIS, E., TERBLANCHE, J. S., KLOK, C. J., LIGHTON, J. R. B. and BLACKBURN, T. M. (2007), Scaling of insect metabolic rate is inconsistent with the nutrient supply network model. Functional Ecology, 21: 282–290. doi: 10.1111/j.1365-2435.2007.01245.x
- Issue published online: 29 JAN 2007
- Article first published online: 29 JAN 2007
- Received 18 September 2006; accepted 14 December 2006Editor: Jan Kozłowski
- intraspecific scaling;
- interspecific scaling;
- metabolic rate;
- metabolic theory of ecology
- 1The nutrient supply network model of the metabolic theory of ecology predicts that metabolic rate scales as mass0·75 at all hierarchical levels.
- 2An alternative, cell size, model suggests that the scaling of metabolic rate is a by-product of the way in which body size changes, by cell size or number, or some combination thereof. It predicts a scaling exponent of mass0·75 at the widest interspecific level, but values of mass0·67−1·0 for lower taxonomic groups or within species.
- 3Here these predictions are tested in insects using 391 species for the interspecific analysis, and the size-polymorphic workers of eight ant species at the intraspecific level. In the latter, the contribution of ommatidium size and number to variation in body length, which is closely related to eye size, is used to assess the relative contributions of changes in cell size and number to variation in body size.
- 4Before controlling for phylogeny, metabolic rate scaled interspecifically as mass0·82. Following phylogenetic correction, metabolic rate scaled as mass0·75.
- 5By contrast, the intraspecific scaling exponents varied from 0·67 to 1·0. Moreover, in the species where metabolic rate scaled as mass1·0, cell size did not contribute significantly to models of body size variation, only cell number was significant. Where the scaling exponent was < 1·0, cell size played an increasingly important role in accounting for size variation.
- 6Data for one of the largest groups of organisms on earth are therefore inconsistent with the nutrient supply network model, but provide support for the cell size alternative.