Interaction of sex and size and the standard metabolic rate of paedomorphic Ambystoma talpoideum: Size does matter

We measured the standard metabolic rate of paedomorphic Mole Salamanders (A mbystoma talpoideum) from South Carolina. Despite an absence of body size d ifferences between females and males, analysis of covariance demonstrated m etabolic rates (mL O-2/h) were significantly influenced by an interaction b etween sex and body size. The interaction appeared as a result of changes i n the size-metabolism relationship in males (a steeper slope in the size-me tabolism regression in small males as compared to large males), whereas the relationship remained constant in females, regardless of size. We hypothes ize that the observed differences are attributable to differences in reprod uctive physiology between the sexes. The results of this study underscore t he need to evaluate the potential interactions among relevant variables in studies of metabolism, which heretofore have been disregarded in studies of salamander physiology.