Locomotor Mode and the Evolution of the Hindlimb in Western Mediterranean Anurans

摘要

The evolutionary association between morphology, locomotor performance and habitat use is a central element of the ecomorphological paradigm, and it is known to underlie the evolution of phenotypic diversity in numerous animal taxa. In anuran amphibians the hindlimb acts as the propulsive agent, and as such, it is directly associated with jumping performance. In this study we combine individual- and species-level analyses to examine the effects of locomotor mode on body size and hindlimb morphology of Western Mediterranean anurans. In addition to the commonly studied hindlimb traits, we also examine the ratio between tibiofibula and femur length. Body size shows no signs of an evolutionary association to locomotor mode. Instead, hindlimb traits are significantly differentiated between locomotor groups, both at the individual and species levels. Specifically, we observe a gradient of tibiofibula to femur ratio values that matches biomechanical predictions. The analysis of adult static allometries indicates that these differences arise early in ontogeny. By comparing the fit of distinct evolutionary models we provide evidence that the locomotor mode adopted by each species to match the requirements of the habitat it frequents has shaped the evolution of the hindlimb, but not body size.