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.
K.J. made substantial contributions to the design and execution of the experiments, interpretation of the findings and drafting and revision of the manuscript. T.E.H. assisted with the design and execution of the experiments, and T.E.H. and A.P.R. were involved in the conception of the study, interpretation of the findings and revising the manuscript.
The authors declare no competing financial interests.
Financial support was provided by the National Science Foundation [grant number IOS-1147043] and start-up funds to T.E.H.
- © 2014. Published by The Company of Biologists Ltd