Circadian activity of the red squirrel, Tamiasciurus hudsonicus, in continuous darkness and continuous illumination.

摘要: In order to examine the effects of constant conditions on wheelrunning activity, 58 red squirrels (Tamiasciurus hudsonicus ) were taken directly from field and placed in either total darkness (DD) or continuous illumination (LL) 500 lux, for up 70 days. The sampled at various times year so that seasonal changes endogenous rhythm could be examined. initial phasing activity correlated with photoperiod had a free-running period (τ) close 24 hours. However,τ increased nearly linear fashion, averaging about 0.19 min/day DD 0.87 LL. All animals LL rhythms which eventually became dissociated into two more components. On other hand, kept running patterns usually remained intact. After being between 20 days, 28 subjected step transitions (500, 350 200 lux) vice versa. An increase level generally resulted phase advance decreasedτ. A decrease delay increasedτ. maximum amount occurred some critical intensity lux. was entrainment phase-angle difference. This relationship compared squirrel's light-pulse response curve. These data support Pittendrigh's (1965) model.