9514585 Jayne There is currently no broad comparative understanding of the neuromuscular basis of locomotor movement of the hind limb of vertebrates because of a lack of information for amphibians and reptiles which generally have a "sprawling" limb posture unlike the "erect" limbed birds and mammals. Lizards are by far the most diverse lineage of vertebrates with the ancestral sprawling limb posture, and the proposed research will quantify the movements and in vivo patterns of muscle use in the hind limbs of this vertebrate lineage. Experiments with a generalized lizard species will test for differences associated with different speeds and locomotion up and down inclines. Three other lizard species with different specialized hind limb postures will be studied similarly allowing quantitative interspecific comparisons of motion and muscle activity. Upside-down locomotion will also be studied for two species of climbing specialists. Overall, the experiments will determine the extent of behavioral diversity in this system and address whether or not major innovations in motor pattern occur either for different locomotor tasks within a species or for similar locomotor tasks among species with differing morphology. It is hypothesized that intraspecific variability in motor pattern of a generalized species performing different tasks may encompass intraspecific variability in motor pattern among species with specialized limb posture. Understanding the functional basis of lizard locomotion will also complement their ecologically and evolutionarily-oriented studies which attempt to relate morphological variation to variation in locomotor performance and habitat selection. ***
