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

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

HERPETOLOGICAL JOURNAL

BRITISH HERPETOL SOC

Año: 2011 vol. 21 p. 35 - 42

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 fundamental components of 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 formula (Pough?s formula) has been proposed to convert SVL into mass. Nevertheless, the predictive power of this formula has been assumed rather than empirically tested for almost three decades. In this paper, we investigate the validity of Pough?s formula using large samples of Liolaemidae lizards (genera Liolaemus and Phymaturus) for which SVL and mass have been measured. Remarkably, we found that Pough?s formula substantially fails to predict body mass in most of the analyses. Among Liolaemus, it only predicted mass at the interspecific level (but not among individuals) and among Phymaturus it was entirely unable to predict realistic body masses. We then conclude that this formula should cautiously be used in lizard ecological and evolutionary research, as assuming its predictive power might result in mistaken conclusions.