Allometric engineering

Allometric engineering is the process of experimentally shifting the scaling relationships, for body size or shape, in a population of organisms. More specifically, the process of experimentally breaking the tight covariance evident among component traits of a complex phenotype by altering the variance of one trait relative to another. Typically, body size is one of the two traits. Manipulations of this sort alter the scaling relationships either by shifting the intercept (b), slope (m) or both to create novel variants (see: Allometry, for more details). These novel variants can then be tested for differences in performance or fitness. Through careful testing, one could sequentially test each component of a trait suite to determine how each part contributes to the function of the entire complex phenotype, and ultimately the fitness of the organism. This technique allows for comparison within or among biological groups differing in size by adjusting morphology to match one another and comparing their performances.

Methods

Current uses have involved truncation or cropping, yolk manipulation, hormonal treatments, maternal allocation, temperature manipulation, or altering the nutritional states. Each method undoubtedly has its merits and pitfalls to consider before designing an experiment, but these techniques are opening new avenues of research in comparative and evolutionary biology.