SPEZZANO JR., L.C.*; JAYNE, B.C.; Univ. of Cincinnati; Univ. of Cincinnati: The effects of incline and perch diameter on the hind limb movements of the arboreal lizard Anolis sagrei

Arboreal species of animals often move on narrow perches with variable inclines, and many species of lizards occupy arboreal habitats. The maximal speeds of locomotion of several species of arboreal Anolis lizards decrease with decreased perch diameter. However, the effects of perch diameter on limb movement and function have not been studied previously for any species of Anolis. Thus, we quantified the hind limb movements of an arboreal lizard Anolis sagrei, on perches with diameters of 1, 3, 6 and 10 cm and inclines of 0&deg, 45&deg and 90&deg and on a flat surface inclined at 0&deg and 45&deg. Anolis sagrei has relatively long limbs (mean distance between the knees of extended limbs = 2.90 cm) and is not considered either morphologically or behaviorally specialized for moving on small diameter perches. We obtained locomotion with no significant variation in speed either among perch diameters or among inclines, and the grand means (N=187) of velocity and duty factor for all strides analyzed from four individuals were 54 cm/s and 54%, respectively. Stride and step length increased significantly as perch diameter increased, and decreased significantly with increased incline. Significantly greater flexion of the knee during stance was an important mechanism for locating the foot more medially when moving on more narrow perches. Pelvic rotation increased significantly with increased incline, but not with changes in diameter. Although several additional kinematic variables changed significantly with perch diameter and incline, most variables differed minimally among 6 and 10 cm diameter perches and the flat surface. Supported by NSF grant IBN 99-83003.