tag:blogger.com,1999:blog-6791792173245944806.post1105802128249110347..comments2023-06-04T17:58:33.117+02:00Comments on ThePEG - Equation of the Month: The Kleiber LawJörgen Ripahttp://www.blogger.com/profile/16338380487214737224noreply@blogger.comBlogger5125tag:blogger.com,1999:blog-6791792173245944806.post-6691923570235596432015-06-28T00:31:56.791+02:002015-06-28T00:31:56.791+02:00In the late 1960s an academic grandchild of Kleibe...In the late 1960s an academic grandchild of Kleiber's invited him to offer a seminar on this topic at Kansas State University, in the school of Veterinary Medicine. As a graduate student in a program for Bio-Environmental Engineering, it was my privilege to attend. It offered not only an opportunity to meet Kleiber, but to buy his text on the topic. At the moment I'm trying to develop a nutritional requirement for a pair of dogs. Likely I'll use my own size and caloric needs to calculate the constants needed to get those canine needs. Might there be a better approach? Comments?Jon Rueckhttp://www.ejmark.orgnoreply@blogger.comtag:blogger.com,1999:blog-6791792173245944806.post-60436605279545844052012-07-04T20:41:49.817+02:002012-07-04T20:41:49.817+02:00Great to see that my guest entry got so many inter...Great to see that my guest entry got so many interesting comments!<br />As Per said above, the Kleiber law describes an observed pattern – a remarkable one, at least in my view – which says absolutely nothing about the underlying processes that produce it. Of course metabolic rate is far from being constant for any species. But without taking such a big-picture view that ignores all the variation over time for an individual and all the between-individual variation for any species, it might have never been noticed! This does of course not mean that all this variation is not important – it depends on the questions you are asking. <br /><br />West et al. tried to come up with a causal explanation for the pattern. Given that the Kleiber law ignores all intraspecific variation in metabolic rate, it’s not a big surprise that their suggested explanation and the MTE that has emerged from it do that as well. So I agree, as almost always in science, there is clearly room for future work here! Maybe someone will at some point even come up with an alternative causal explanation for the Kleiber law that doesn’t require the fractal structure of the circulatory system as an ingredient.Barbara Fischernoreply@blogger.comtag:blogger.com,1999:blog-6791792173245944806.post-32910153851028506222012-07-04T15:36:33.797+02:002012-07-04T15:36:33.797+02:00Kleiber's law, or any other scaling law, is an...Kleiber's law, or any other scaling law, is an attempt to mathematically describe an observed pattern. Similar models can do this good or less well. Those models do not, however, necessarily tell us anything about from where this pattern emerges. Where does "3/4" or "2/3" really come from?<br />My understanding is that MTE's ambition is to do precisely that - to figure out where scaling comes from in the first place. Wether it has succeed is beyond me to judge.<br /><br />Kleiber found the pattern, others have tried to refine the description of it and now we should find out where it comes from.<br /><br />Nice to see so many comments on this post, by the way!Per Lundbergnoreply@blogger.comtag:blogger.com,1999:blog-6791792173245944806.post-69177977258742413742012-07-04T09:05:27.700+02:002012-07-04T09:05:27.700+02:00The way that the allometric scaling exponents are ...The way that the allometric scaling exponents are derived has also come under fire. A straight line is fitted to the data even if this is not the best relationship from a statistical or information theory standpoint. The log-log plots used to calculate the metabolism-mass slope do not well describe the arithmetic relationship, although the latter is what we use to discuss allometry. The allure of a finding some sort of constant throughout all biology has made us somewhat selective about what data we choose to include/exclude in meta-analyses, and we often forget about mathematical and statistical rigor. <br /><br />An articles for the interested:<br /><br />Packard, G.C., Boardman, T.J., 2008. Model selection and logarithmic transformation in allometric analysis. Physiological and Biochemical Zoology 81, 496-507.Damian Moranhttp://www.microcosmofscience.comnoreply@blogger.comtag:blogger.com,1999:blog-6791792173245944806.post-76627000898574840872012-06-29T11:51:26.264+02:002012-06-29T11:51:26.264+02:00In spite of the importance of the law and the subs...In spite of the importance of the law and the subsequent MTE I'd like to stress that it is even more important to step back and look at what MTE is based on:<br /><br />The data used are measurements of basal and standard metabolic rate (BMR and SMR), meaning animals at rest. Are animals resting all the time? It is a fact that 'normal metabolic rate' have a different scaling, as e.g. the maximal metabolic rate scales with an exponent significantly larger than 3/4 (e.g. Killen et al. 2007). This effect is due to all kinds of activity.<br /><br />Currently we're missing quantitative theories of metabolism that can accurately assess both magnitude and changes in slope with activity levels. As an example the fishes spend about 80% of their energy on activity which is not dealt with in MTE. We should thus work on expanding the metabolic theory and incorporating it into trophic food web models such that we make quantitative predictions of energy exchanges in natural systems.<br /><br />DEB models (Kooijman 2000) aim at solving this problem. However, these models are mostly based on fit to growth curves, which do not allow for proper estimation of energy intake and expenditures as they fit to the difference between the two. We need to focus on descriptions of both uptake and expenditures to provide the desired quantitative description of energy exchanges.<br /><br />Lastly we should not forget that even though the mass-specific rate is strikingly similar across body size there is still 2 orders of magnitude in difference across taxa (Makarieva, 2008)... a difference that indeed is significant if we ever hope to quantitatively descripe energy exchanges in natual systems.<br /><br />MTE has provided a lot of knowledge on interspecific scaling of metabolism. It's now time to focus on intra-specific relationships.<br /><br />Just a few thoughts,<br />Martin Hartvig<br /><br /><br />References<br /><br />Killen, S. S.; Costa, I.; Brown, J. A. & Gamperl, A. K. Little left in the tank: metabolic scaling in marine teleosts and its implications for aerobic scope. Proc. R. Soc. B, 2007, 274, 431-438<br /><br />Kooijman, S. A. L. M. Dynamic Energy and Mass Budgets in Biological Systems. Cambridge University Press, 2000<br /><br />Makarieva, A.; Gorshkov, V.; Li, B.; Chown, S.; Reich, P. & Gavrilov, V. Mean mass-specific metabolic rates are strikingly similar across life's major domains: evidence for life's metabolic optimum. Proc. Natl. Acad. Sci. USA, 2008, 105, 16994Martin Hartvighttp://hvig.dknoreply@blogger.com