EFFECTS OF INCLINE ON SPEED, ACCELERATION BODY POSTURE AND HINDLIMB KINEMATICS IN 2 SPECIES OF LIZARD CALLISAURUS-DRACONOIDES AND UMA-SCOPARIA

We examined the effects of incline on locomotor performance and kinema tics in two closely related species of iguanian lizards that co-occur in sandy desert habitats, Callisaurus draconoides differs from Ulna sc oparia of equal snout-vent length by being less massive and having gre ater limb and tail lengths. We analyzed high-speed video tapes of liza rds sprinting from a standstill on a sand-covered racetrack which was level or inclined 30 degrees uphill, C. draconoides sprinted significa ntly faster than U. scoparia on both level and uphill sand surfaces, a lthough U, scoparia is considered to be more specialized for sandy hab itats. Initial accelerations (over the first 50 ms) did not differ sig nificantly either between species or between inclines within species. Overall, the effects of incline were more pronounced for C. draconoide s than for U. scoparia, For example, the incline caused a significant decrease in the maximum stride length of C. draconoides but not in tha t of U. scoparia, For C, draconoides, uphill stride durations were sig nificantly shorter than on the level surface, and this partially compe nsated for the effects of shorter uphill stride lengths on velocity, C . draconoides ran bipedally more often than did U. scoparia on both th e level and uphill surfaces.