The Effects of Caudal Autotomy on the Kinematics of Anolis carolinensis Running on an Arboreal-Like Substrate



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Caudal autotomy is a well-researched predation-escape mechanism used by Anolis lizards. This ‘self-sacrifice’ involves a neuromuscular event in which the tail is severed along an intravertebral fracture plane proximal to the point of a predator’s grip. The phenomenon of autotomy has persisted in anoles for millions of years due to its benefit of increasing the probability of survival. However, autotomy also incurs in the lizard a metabolic deficit, behavioral modifications, and locomotor consequences. Past research has documented post-autotomy changes in sprint speed, step length, and time spent pausing. I hypothesize that these gross locomotor effects can be explained by changes in limb kinematics. Using high-speed video cameras and MATLAB I recorded and compared the characteristic motions of the front and hind legs pre- and post-autotomy in running Anolis carolinensis (N=4), a trunk-crown anole with morphology representative of a broad range of anole ecomorphs. Post-autotomy, the lizards showed significant increases in average velocity, forelimb step frequency, and hindlimb step frequency (p=0.025; p=0.02; p=0.035). Kinematic variables of the limb did not significantly change after tail loss, so the gross locomotor changes observed are better explained as behavioral than biomechanical.



biomechanics, anole, locomotion, caudal autotomy