EVOLUTION OF FORELIMB MOVEMENT PATTERNS FOR PREY MANIPULATION IN ANURANS

Unlike other amphibians, frogs often use their forelimbs to capture an d transport prey. In the present study, high-speed videography was use d to observe forelimb use during feeding in a diverse group of anurans in order to determine the evolution of forelimb movement patterns amo ng anuran taxa. Data were gathered from 488 individuals representing 1 04 species, 55 genera, and 16 families. Five distinct behavior pattern s were identified: scooping entails using the back of the hand to push prey into the mouth; wiping involves the use of the palm of the hand to push prey, protruding laterally from the mouth, toward the midline; during prey stretching, one end of the prey is held in a stationary p osition by the hands while the other end is pulled upward by the jaws; in grasping, the palms face the midline or the substrate as the finge rs are wrapped around the prey; grasping with wrist rotation is simila r to grasping, but the wrists rotate inward as the hands grasp the pre y so that the palms face the mouth. The distribution of these behavior patterns was mapped onto the most recent phylogenetic hypothesis for anurans. Maximum parsimony analyses suggest that scooping and wiping a re primitive and have been retained by many frog lineages. Wiping was not observed in the pipids, which are the only anurans that lack tongu es and use hydraulic transport. Prey stretching appears to have evolve d several times in unrelated taxa. Grasping and grasping with wrist ro tation appear to have evolved only in arboreal groups, suggesting that the ability to climb is a preadaptation for the ability to grasp prey . Several species mere observed using grasping motions in place of the tongue to capture prey. (C) 1997 Wiley-Liss, Inc.