Meeting Abstract
Terrestrial animals must effectively navigate structurally complex environments. For geckos, non-level substrata are important because the adhesive system engages during uphill locomotion, limiting sprint speed due to the increased time that is required to deploy and disengage the adhesive toe pads. Our previous research indicates that Rhoptropus afer, relying on fast sprints to escape, avoid the steepest available inclines and declines during predator evasion. Additionally, one population predominantly avoids inclines in its habitat, and exhibits reduced adhesive toe pad size. To understand the interplay between habitat use, escape behavior, and morphology, we quantified the 3D kinematics of R. afer on level and uphill surfaces. We recorded 45 individuals on a 1.5 m trackway angled at 0° and 30°. Corroborating previous studies, speed decreased during uphill locomotion, driven by decreased stride frequency and increased stance time, but not stride length. The timing and use (on/off) of digital hyperextension was variable within and among treatments, yet was employed more often during uphill locomotion. Furthermore, curvature of the longest hind-limb digit was also affected by incline. The coefficient of variation was calculated to determine relative stereotypy among distal and proximal kinematics, incline, and populations. Specifically, we test the hypotheses that kinematics are more stereotyped on 30° due to the increased reliance on the adhesive system, and that distal limb elements are generally more stereotyped than proximal elements due to the highly integrated adhesive system. We dissect individual variation and the effects of incline on locomotion, and how these features relate to predator evasion and habitat use in the field. Supported by NSF IOS-1147043.
