| Abstract: | In order to contribute to a comparative view on lacertids, the effect of pinealectomy on the freerunning activity displayed under constant darkness and temperature (27.5°C ± 0.5) has been studied in the lizard Gallotia galloti eisentrauti . Animals showed an entrained motor activity rhythm under an initial light-dark (12:12 hours) routine and freerunning circadian periods ranging between 24.1 and 25.5 h during constant darkness (periodograms obtained by Sokolove & Bushell's method). After pinealectomy, most animals showed no significant circadian rhythm, their locomotor activity becoming diffuse throughout the whole 24 h period. Thus, the pineal gland seems to play an important role as a main pacemaker regulating the endogenous activity rhythm under constant conditions. This result contrasts with that found in Podarcis sicula where after pinealectomy only changes in length of the freerunning period were found. |
