Allometric Growth of the Hind Limbs of Some Terrestrial Iguanid Lizards

Parameters of the allometric equation (y = bxα) were estimated for relative growth in the length of hind-limb elements vs. body length in five species of terrestrial iguanid lizards. Measurements of shank, thigh and snout-vent length were made on preserved samples, each representing a cross section of age classes from a restricted geographic locality Both positive allometry (α > 1) and negative allometry (α < 1) were observed, the latter being more common. These results are consistent with Kramer's (1951) hypothesis that lizards should commonly show negative allometric growth of the hind limbs, which enhances the locomotor ability of vulnerable hatchlings. Dodson's (1975) hypothesis that positive allometry of hind limbs is correlated with an increase in home range size during ontogeny is not supported. We hypothesize that positive allometry in male scrub lizards represents a temporal patterning of investment in morphology in relation to a change in defensive behavior during ontogeny Allometric growth in lizards may also be explicable in the context of maintaining similar biomechanical function with increasing size, or in terms of altering biomechanical function during ontogeny as in Laerm's (1974) habitat-shift model.