THE INTERACTION OF BEHAVIORAL AND MORPHOLOGICAL CHANGE IN THE EVOLUTION OF A NOVEL LOCOMOTOR TYPE: "FLYING" FROGS

"Flying" frogs have evolved independently several times among anurans. In all cases flyers are distinguished from their nonflying arboreal relatives by a unique set of morphological features and behavioral postures. Using both live animal field tests and wind tunnel models, this study examines the importance of this characteristic morphology and limb position on five aerial performance variables: horizontal traveling distance, minimum glide speed, maximum time aloft, maneuverability, and stability. Comparison of relative performance between a model frog with a generalized nonflying morphology and limb position and a model frog with flying morphology and limb position reveals that the morphological and positional features associated with "flying" actually decrease horizontal traveling distance but improve maneuverability. This finding suggests that maneuverability rather than horizontal travel may be the key performance parameter in the evolution of "flying" frogs. More generally, this study illustrates that (1) derived morphological and postural features do not necessarily change a suite of performance variables in the same way, and (2) the performance consequences of postural shifts are a function of morphology. These findings indicate that the potential complexity of morphological and behavioral interactions in the evolution of new adaptive types is much greater than previously considered.