Body size as a latent variable in a structural equation model: thermal acclimation and energetics of the leaf-eared mouse

Nespolo, RF; Arim M.; Bozinovic F.

Abstract

Body size is one of the most important determinants of energy metabolism in mammals. However, the usual physiological variables measured to characterize energy metabolism and heat dissipation in endotherms are strongly affected by thermal acclimation, and are also correlated among themselves. In addition to choosing the appropriate measurement of body size, these problems create additional complications when analyzing the relationships among physiological variables such as basal metabolism, non-shivering thermogenesis, thermoregulatory maximum metabolic rate and minimum thermal conductance, body size dependence, and the effect of thermal acclimation on them. We measured these variables in Phyllotis darwini, a murid rodent from central Chile, under conditions of warm and cold acclimation. In addition to standard statistical analyses to determine the effect of thermal acclimation on each variable and the body-mass-controlled correlation among them, we performed a Structural Equation Modeling analysis to evaluate the effects of three different measurements of body size (body mass, mb; body length, Lb and foot length, Lf) on energy metabolism and thermal conductance. We found that thermal acclimation changed the correlation among physiological variables. Only cold-acclimated animals supported our a priori path models, and mb appeared to be the best descriptor of body size (compared with Lb and Lf) when dealing with energy metabolism and thermal conductance. However, while mb appeared to be the strongest determinant of energy metabolism, there was an important and significant contribution of Lb (but not Lf) to thermal conductance. This study demonstrates how additional information can be drawn from physiological ecology and general organismal studies by applying Structural Equation Modeling when multiple variables are measured in the same individuals.

Más información

Título según WOS: Body size as a latent variable in a structural equation model: thermal acclimation and energetics of the leaf-eared mouse
Título según SCOPUS: Body size as a latent variable in a structural equation model: Thermal acclimation and energetics of the leaf-eared mouse
Título de la Revista: JOURNAL OF EXPERIMENTAL BIOLOGY
Volumen: 206
Número: 13
Editorial: COMPANY OF BIOLOGISTS LTD
Fecha de publicación: 2003
Página de inicio: 2145
Página final: 2157
Idioma: English
URL: http://jeb.biologists.org/cgi/doi/10.1242/jeb.00396
DOI:

10.1242/jeb.00396

Notas: ISI, SCOPUS