Role of light/dark schedules on daily pattern of total locomotor activity in wild and domestic felids.
Circadian rhythms of the physiological and behavioral variability are an inherent property of mammals, and closely related to environmental factors. Light is the best-known environmental entrainment of the circadian pacemaker. The aim of the present study was to investigate the light/dark (L/D) cycle role on the entrainment of the total locomotor activity daily rhythm recorded by means of an activity data logger in felids. 5 Geoffroy's cats, 5 jaguarondi, and 5 domestic cats were subjected to 12/12 light/dark cycle (L/D1), constant light (L/L), and 12/12 light/dark cycle (L/D2). Food and water were available ad libitum. Four rhythmic parameters (mesor, am- plitude, acrophase, and robustness) were assessed and compared among the 3 species, the L/D schedules, and the days of monitoring. Daily rhythmicity of total locomotor activity was observed in all L/D schedules, in the 3 species. An influence of L/D schedules, species, and days of monitoring on the circadian parameters of total locomotor activity daily rhythm was observed. Mesor, amplitude, and robustness of rhythm were statistically different among L/D schedules, species, and day of monitoring. Acrophase was statistically different among L/D schedules and species. Acrophase was observed during the scotophase in Geoffroy's cats and domestic cats. A significant effect of photoperiod was observed in Geoffroy's cats with a shift in L/L respect to L/D1. Our result showed that locomotor activity in felids is endogenously generated, it is peculiar to each species investigated, and that 9 days were not enough to re-establish the daily rhythmicity due to the L/D cycle.