Melatonin and photoperiod affect body temperature selection in the lizard Lacerta viridis

Abstract

1. 1. Body temperature T b of Lacerta viridis was monitored telemetrically under natural photoperiod. 2. 2. At the end of August (LD 14:10) one group of lizards was placed in a short day photoperiod (LD 8:16) and one group received melatonin implants and was maintained at the prevailing long photoperiod. 3. 3. After 3 weeks both groups showed a modified T b selection pattern similar to that seen under natural photoperiod in fall. 4. 4. Since melatonin mimicked the effect of short photoperiod on T b selection, it is surmised that this hormone is involved in mediating photoperiodic information which may influence seasonal cueing of thermoregulatory responses.