Normalizing physiological data for scleractinian corals

Increasing body size exposes the structural, functional, and geometric constraints of phenotype design (Schmidt-Nielsen 1984) which result in scaling effects that have a pervasive and profound influence on organismic physiology (Gould 1966; Schmidt-Nielsen 1984). In experimental research, the confounding effects of size (i.e., scaling) can be minimized by comparing organisms of similar size, or by comparing organisms of different size after normalizing the results to a metric that reflects size. Size normalization assumes a proportional relationship (i.e., isometry) between size and the trait of interest (Packard and Boardman 1988), yet the assumption of isometry is rarely demonstrated and most traits scale disproportionately with size (i.e., allometry). Isometry characterizes only a small number of taxa, and includes the colonial modular organisms like bryozoans (Hughes and Hughes 1986) and, theoretically, the scleractinian corals (Jackson 1979; Sebens 1987).