title: Tail autotomy and subsequent regeneration alter the mechanics of locomotion in lizards.
abstract: Animals can undergo significant weight change for a variety of reasons. Autotomy, the voluntary shedding of an appendage in response to a predator stimulus, provides an effective model for measuring the effects of rapid weight change on locomotor behavior and the responses to more gradual weight gain, particularly in lizards capable of both autotomizing and regenerating their tail. Although the general effects of autotomy on locomotor performance are commonly explored, we investigated changes in locomotor mechanics associated with tail loss and long-term regeneration for the first time by measuring morphology, 3D kinematics and ground reaction forces (GRFs) in the leopard gecko Eublepharis macularius. Tail autotomy resulted in a 13% anterior shift in the center of mass (CoM), which only partially recovered after full regeneration of the tail. Although no changes in body or forelimb kinematics were evident, decreases in hindlimb joint angles signify a more sprawled posture following autotomy. Changes in hindlimb GRFs resulted in an increase in weight-specific propulsive force, without a corresponding change in locomotor speed. Hindlimb kinematics and GRFs following autotomy recovered to pre-autotomy values as the tail regenerated. These results suggest an active locomotor response to tail loss that demonstrates the causal relationships between variations in morphology, kinematics and force.
authors.affiliation: Department of Evolution, Ecology, and Organismal Biology, University of California, Riverside, 900 University Avenue, Riverside, CA 92521, USA kevin.jagnandan@email.ucr.edu.
authors.forename: Kevin
authors.initials: K
authors.lastname: Jagnandan
authors.affiliation: Department of Biological Sciences, University of Calgary, 2500 University Drive NW, Calgary, AB T2N 1N4, Canada.
authors.forename: Anthony P
authors.initials: AP
authors.lastname: Russell
authors.affiliation: Department of Evolution, Ecology, and Organismal Biology, University of California, Riverside, 900 University Avenue, Riverside, CA 92521, USA.
authors.forename: Timothy E
authors.initials: TE
authors.lastname: Higham
mesh_terms: D000704:Analysis of Variance; D000818:Animals; D001696:Biomechanical Phenomena; D001835:Body Weight; D021621:Imaging, Three-Dimensional; D008116:Lizards / Q000502:physiology*; D008124:Locomotion / Q000502:physiology*; D011187:Posture / Q000502:physiology*; D012038:Regeneration / Q000502:physiology*; D013623:Tail / Q000033:anatomy & histology / Q000502:physiology*
keywords: Biomechanics; Center of mass; Ground reaction force; Kinematics; Locomotion; Regeneration; Tail autotomy