The Herpetological Journal

pp. 35-42
Authors: Pincheira-Donoso, D.; Fox, S.F.; Scolaro, J.A.; Ibargüengoytía, N.; Acosta, J.C.; Corbalán, V.; Medina, M.; Boretto, J.; Villavicencio, H.J. & Hodgson, D.J.

Abstract: Body size influences patterns of variation in several of the most important traits directly linked to fitness. Therefore, the establishment of informative proxies for body size is a critical aim in ecological and evolutionary research. Among lizards, snout–vent length (SVL) is the most widely used proxy for body size. However, since SVL is a linear measure of size, it fails to capture body shape variation. This limitation is largely resolved by the use of body mass, a multidimensional measure of size that is unfortunately rarely considered and reported. To circumvent this restriction, a classic allometric equation (Pough's equation) was proposed to convert SVL into mass. Nevertheless, the predictive power of this equation has been assumed rather than empirically tested for almost three decades. In a recent study on lizard size allometries, additional equations were derived for different groups separately, suggesting that more clade-specific equations are likely to perform better. Here, we investigate the precision of these allometric equations using two sister lizard genera (Liolaemus and Phymaturus), members of the Liolaemidae radiation, for which SVL and mass have been measured. We found that our equations differ significantly from the two more general equations primarily in intercepts, while the more clade-specific equation derived for Tropiduridae lizards is fully compatible with our equation for Liolaemus and showed only a borderline statistical difference with Phymaturus. Therefore, although more clade-specific equations may reliably predict body mass, more general equations should be used with caution in lizard ecological and evolutionary research. Previous allometric equations proposed to predict mass from length in other ectotherms should be quantitatively assessed before being employed.

Keywords: LIZARDS, PHYMATURUS, LIOLAEMUS, ALLOMETRY, BODY MASS