Meeting Abstract
By using adhesion, geckos can navigate through challenging habitats. Given the importance of the foot in transmitting forces to the substrate and adhesive system application, the directionality of adhesion is likely critical. Behaviorally modulating how the adhesive system is applied can occur by altering the alignment of the foot relative to the long axis of the body and/or the angles between the digits (interdigital angle). Given the directionality of the adhesive system, we expect geckos to vary the application of the system via these mechanisms as they run. We quantified 3D movements (with high-speed video) of Phelsuma madagascariensis running on a range of ecologically relevant inclines (0°, 45°, 90 °) and perch diameters (1.5cm, 10cm and flat). We measured instantaneous interdigital angle and foot alignment relative to the body across each condition, as well as other kinematic variables. The geckos decreased speed with decreasing perch diameter, but increased speed at 45°. This suggests that P. madagascariensis may favor inclined perches. Additionally, proximal limb variables respond to substrate condition in a manner to increase stability and reduce toppling. Finally, foot alignment in the forelimb acts in opposition to that of the hindlimb, suggesting that P. madagascariensis is able to maintain multiple directions of adhesion at one time. The modulation of interdigital angle and foot alignment suggests that aspects other than the mechanism of adhesion are important for arboreal movement in geckos. Our study reveals patterns of foot usage in arboreal locomotion, which can lead to a better understanding of adhesive system constraints. This is essential for understanding how biomechanical traits respond to the evolution of novel adaptations and morphologies. Supported by NSF IOS-1147043.
