Allometric and ecological relationships of ventricle and liver mass in anuran amphibians

Abstract

Summary There is an isometric relationship for allometry of ventricle mass (slope = 0·952) and liver mass (slope = 1·027) and phylogenetic correlations of ventricle and liver mass for museum specimens of 42 species of Australian frogs. There was a strong relationship for ventricle mass with body mass, phylogeny and dehydration tolerance, but not habit, body shape or environmental variables. The relatively large ventricle of more dehydration‐tolerant species may also be associated with a higher metabolic scope for activity. There was a strong relationship for liver mass with body mass, phylogeny, habit (burrowing, terrestrial, arboreal), body shape and some environmental variables, but not dehydration tolerance. For burrowing frogs, a relatively large liver is presumably important because it is an energy store during long periods of dormancy and is a source of amino acids for cocoon formation or urea synthesis. For arboreal frogs, a small liver might reduce the cost of transport by limiting body mass, and allow a more elongate shape. Relative ventricle mass of museum specimens is representative of values for field‐collected frogs. Relative liver mass is higher for museum specimens; this might be an artefact of museum preservation and/or reflect seasonal or geographic variation.