THE ROLE OF EXTRARETINAL PHOTORECEPTION IN THE CIRCADIAN SYSTEM OF THE RUIN LIZARD PODARCIS-SICULA

1. Combination of parietalectomy, pinealectomy and retinalectomy in the same individual does not prevent Podarcis sicula from obeying Aschoff's rule for diurnal animals. 2. In these operated lizards an increase in intensity of constant illumination (LL) shortens the freerunning period of locomotor rhythms, while a decrease in LL intensity has the opposite effect. 3. These results demonstrate that: (i) extraretinal photoreceptors play a role in mediating parametric effects of light on the circadian system (Aschoff's rule); (ii) extraretinal photoreceptors mediating parametric effects of light lie outside the parietal eve and the pineal.