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Allometry is the study of the change in proportion of various parts of an organism as a consequence of growth - Huxley 1932. But historically #allometry has mainly been viewed or used through three differing lenses...
1. The prediction of correlated evolutionary changes e.g. Gould (1975) if intraspecific allometry represents the correlated variability upon which selection operates, then allometric rates of change follows changes in body size, if size alone is the object of selection.
2. Allometry as a "null hypothesis" Observed variation can be subsumed in the more general explanation of size variation, and no special explanation (particularly one invoking adaptation) is needed e.g. Gould and Lewontin, 1979.. Gould's Irish Elk example, 1974
3. Use of allometric function as a ‘trait(s)’ subject to selection - If the ontogenetic allometric coefficient and/or exponent is characteristic of a population or species, there is no reason in principle why the coefficient might not be used as a "character".
Allometry is arguably one of the most studied, debated, but also least understood phenomena in biology. I suspect many would disagree or amplify these statements. Nevertheless, the mechanisms that underlie allometric integration are far from obvious....
The "continued challenge in the study of allometry is to move from describing the patterns of scaling relationships to understanding the underlying processes that create those patterns." https://www.nature.com/scitable/knowledge/library/allometry-the-study-of-biological-scaling-13228439/
Because allometric functions are often 'power-laws' - The allometric function can be shown to be the solution of the differential equation relating the specific growth rates of two traits X and Y with respect to time - Reeve and Huxley (1945)
Power-laws, i.e. L(s) = b s^k where b and k are constants, arise in the context of self-similar functions. "whenever evolution has conserved the genetic networks ...so that structures are, from one individual to the next, very nearly the same shape" https://jbiol.biomedcentral.com/articles/10.1186/jbiol119
"But, I dont study allometry..." is often heard when presenting in front of those who have not yet read Huxley, Gould, Calder, Cheverud, Peters etc... Why should allometry be a core focus in biology today?
To quote animal centric Bartholomew (1981) "It is only a slight overestimate to say that the most important attribute of an animal both physiologically and ecologically, is its size. Size constrains virtually every aspect of structure and function"
