THE PINEAL AND CIRCADIAN-RHYTHMS OF TEMPERATURE SELECTION AND LOCOMOTION IN LIZARDS

The existence of a circadian rhythm of behavioral temperature selectio n has been demonstrated in lizards (Podarcis sicula) held on a thermal gradient in constant darkness. This rhythm becomes temporarily abolis hed during 1 week following parietalectomy and 2-3 weeks following pin ealectomy. Parietalectomy does not affect the locomotor rhythm, while pinealectomy invariably lengthens the freerunning period of this rhyth m. These results support the contention of separate control systems fo r the temperature selection rhythm and the locomotor rhythm. As neithe r rhythm is definitively abolished by parietalectomy and pinealectomy, other pacemaking components exist elsewhere in the circadian system o f Podarcis sicula which can control both rhythms.