DEBAN, S.M.*; O’REILLY, J.C.; NISHIKAWA, K.C.: The evolution of the motor control of feeding in amphibians.

We compared prey capture among salamanders, frogs and caecilians in a phylogenetic context to identify major evolutionary transitions of the motor control of amphibian feeding. The common ancestor of living amphibians was most likely a predator with a free-living aquatic larval life stage. A combination of visual, olfactory, tactile and lateral line (in water) cues triggered feeding. Suction feeding was used in water and jaw prehension on land. Feeding kinematics were influenced by both feed-forward and feedback information. The primitive feeding behavior of salamanders most resembles that of this theoretical ancestor. Derived conditions within salamanders include 1) the evolution of elaborate, visually-controlled tongue protraction correlated with decreased lunging and 2) the reduction of vision in some groups and the concomitant dominance of other senses in triggering and modulating feeding. In the common ancestor of frogs, the tongue was short and lunging was necessary for prey capture. The visual system dominated other senses in triggering and modulating feeding and ampullary organs were lost, precluding the use of electrical cues. Derived conditions in frogs include 1) the repeated evolution of long tongues with a correlated decreased in lunging and 2) the dominance of olfactory and tactile sensory modalities in many burrowing, termite-eating species. Metamorphosed caecilians still use jaw prehension to capture prey. The ability to form visual images was lost ancestrally, as was the role of vision in feeding. Thus, the extensive variation seen in caecilian feeding kinematics is apparently driven by olfactory and tactile cues. Derived conditions among caecilians include the apparent use of electrical cues during feeding in aquatic species.