HAZARD, L.C.; MILLER, J.M.*; MARTINEZ, J.; SINERVO, B.; Univ. of California, Santa Cruz; Univ. of California, Santa Cruz; Univ. of California, Santa Cruz; Univ. of California, Santa Cruz: Ontogeny of physiological performance of side-blotched lizards (Uta stansburiana)

Physiological performance can influence foraging ability, predator avoidance, or reproductive success, and is therefore often measured in adult animals, with implications for fitness discussed. However, animals are subject to predation pressure and foraging needs throughout their lives. We tracked physiological performance of ~90 lab-reared side-blotched lizards (Uta stansburiana) from just after hatching to reproductive maturity, one year later. Trials were conducted in June 2002, September 2002, December 2002, and May 2003. Maximum sprint speed, willingness to run (number of stops made), and number of reversals (an anti-predator tactic) were measured on a 150-cm racetrack (using either digital video or photocells and datalogger with timer). Stamina (time run on a treadmill until loss of righting response) was measured for the last three trials. Performance was highly variable and improved with age in the first three trials (higher sprint speed, fewer stops and reversals), but declined in the fourth trial, possibly due to poor recovery of the animals from hibernation; data for this trial were excluded from most analyses. There was a slight but significant effect of body mass on sprint speed within Trial 1 and on stamina within Trial 2, but no other within-trial effects of mass. Sprint speed, stamina, and number of stops had low but significant repeatabilities.