A simplified model for bivariate complex allometry.

A three-parameter relationship passing through the origin can be derived from the Gompertz growth curve and provide a simplified but useful description of complex allometry, where variates are not proportional to powers of each other as in simple allometry. Partial linearization is often satisfactory and, after a double logarithmic transformation, the allometric relationship is non-linear only with respect to an exponent of complex allometry, D, which reflects the presence (E # 1) or absence (D = 1) of a curvature in log-log space and provides an approximate test of the hypothesis of simple allometry. Examples are presented concerning growth allometry in white rats, metabolic allometry in placental mammals, and size allometry in the Paddlefish, in the North American Marten and in the Painted Turtle.