Body size dimensions in lizard ecological and evolutionary research: exploring the predictive power of mass estimation equations in two Liolaemidae radiations

D. PINCHEIRA-DONOSO, S. F. FOX, J. A. SCOLARO, N. IBARGUENGOYTIA, J. C. ACOSTA, V. CORBALÁN, M. MEDINA, J. BORETTO, H. J. VILLAVICENCIO, D. J. HODGSON

HERPETOLOGICAL JOURNAL

BRITISH HERPETOL SOC

Año: 2010 p. 1 - 2

0268-0130

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 which 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 significantly differ primarily from the two more general equations 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.