Lecturer: Bas Kooijman
Affiliation: retired from VU University Amsterdam
Symposium: ICCPB at Krakow University.
Date: 2015/08/24
Title: Metabolic scaling in the perspective of DEB theory

Abstract:
Kleibers law, i.e. respiration is proportional to body weight to the power 3/4, interspecifically, still generates discussion since it is generally seen as explantion for many biological scaling phenomena.
Since 1986, Dynamic Energy Budget (DEB) theory offers a sound explantion for this law.
Compared to alternative explanations, three issues need discussion: (1) respiration, (2) body weight, (3) allometric functions.

Ad (1): Alternative explantions are much too sloppy about what quantifies respiration. Indirect colorimetry treats heat production as a weighted sum of dioxygen consumption, carbon dioxide production and nitrogen waste production. These fluxes are not proportional to each other and the weight coefficients are taxon-specific. Respiration defined as dioxygen consumption is a problematic quantifier for metabolic rate, especially in the context of DEB theory.
This theory deals with reserve as quantifier for metabolic memory and with egg production as export of reserve. Although reproduction is an important metabolic activity, it has little effect on respiration. Moreover, anearobic species don't respire, but are metabolically active.
The ratio between peak and standard metabolism strongly increases from supply to demand species.

Ad (2): Maximum body weight is itself a result of underlying procoesses. Within the DEB context, it has contributions from reserve and structure, were only structure requires somatic maintenance, which is one of the contributions to respiration. Maximum body weight is itself a function of DEB parameters.

Ad(3): Since respiration has additive contributions from different metabolic processes, it cannot be an allometric function of body weight. The proportionaly with weight to the power 3/4 can only be very approximative, and many exceptions exist, which DEB theory captures well.

DEB theory treats Kleibers law as a special case of wider problem of co-variation of parameters across species. The rules for co-variation follow from physical dimension analysis and do not involve empirical or optimazation arguments. Both maximum body weight and maximum respiration are just two functions of some parameters. They do not contain all parameters, and many interesting phenemona involve other parameters as well. Respiration, with contributions from several underlying processes, cannot serve as explantion for scaling phenoma generally. DEB thoery offers a simple quantifier for where species are on the supply-to-demand spectrum, with a direct link to the ratio between peak and standard metabolism. I will also discuss the waste-to-hurry phenomenon to illustrate some points.

Reference:
  http://www.bio.vu.nl/thb/research/bib/Kooy2010.html
  http://www.bio.vu.nl/thb/research/bib/Kooy2013.html
  http://www.bio.vu.nl/thb/research/bib/LikaAugu2014.html
  http://www.bio.vu.nl/thb/research/bib/BaasKooy2015.html