No abstract

The injIuence ofbody temperature (12.5"-37" C) and therrnal acclimation (20" a1ld30" C) on spri~lt speed in a thigmothermic lizard, Xantusia vigilis, was rneasured IJodjl temperature has aprofot~ind influence on sprint speed, which is maximal at 33'-34" Cand declines exponentialb~ at lower body temperatures. Neither sprint speed nor its thermal dependence was modijied bji thermal acclimation over the bodjl temperature range of 15.0"-34' C. In contrast, acclimation temperature. did affect sprint speed at more extreme temperatures: 20° C-acclimated lizards ran ,faster-at 12.5' and slower at 3 7" C than did 30" C-acclimated animals. Acclimation also affectedprtIferred body temperatures and critical thermal minima and maxima: all were significa~dy lower in the 20" C-acclirnatedgroup (31. I > 4.5", and 40.5" C, respectivelj~) than in the 30" C-acclirnatedgrot~p (3.3. 0" , 9.4", 43.0"). Acclimation may therefore sl%fi critical thermal variables without affecting locomotor performance at intermediate ternperatures.