Meeting Abstract
138.4 Monday, Jan. 7 Neuromuscular control of arboreal locomotion: how green anoles (Anolis carolinensis) deal with changes in incline and perch diameter FOSTER, K.L.*; HIGHAM, T.E.; Univ. of California, Riverside; Univ. of California, Riverside kfost001@ucr.edu
Arboreal habitats comprise a diverse array of inclines, substrate diameters, and obstacles that pose considerable functional challenges for locomotion. Arboreal lizards often alter limb kinematics as they execute the complex maneuvers necessary in this habitat. However, there is virtually no information regarding how limb muscles control and propel arboreal lizards. We assessed activity patterns of the biceps dorsalis, puboischiotibialis, ambiens pars dorsalis, caudofemorsalis, and peroneus brevis and longus using synchronized electromyography (EMG) and three dimensional high speed video of 9 adult male green anoles (Anolis carolinensis) running on flat (9cm wide) and small, round (1.3cm diameter) perches inclined at 0o, 45o, and 90o. The majority of muscles exhibited two bursts per stride, the first of which occurred during stance and had a greater amplitude and longer duration than the second. The activity patterns of all muscles were consistent with the propulsive functions hypothesized based on anatomy, although several appeared to have secondary antagonistic functions during the swing phase. Although EMG amplitude generally correlated positively with angular excursion of the corresponding joint, activity levels in the biceps, caudofemoralis, and peroneus were disproportionately greater at 90o, especially on the narrow perch, suggesting steep, small diameter perches may be suboptimal from a physiological perspective. However, the reverse was true on the small diameter inclined at 45o for the ambiens, which exhibited decreased recruitment despite greater knee extension than the other treatments. We show that these muscles respond differently to the challenges of perch diameter and incline and suggest that their relative contribution to propulsion may shift.
