PHOTOPERIODICITY IN DAILY RHYTHMS OF BODY-TEMPERATURE, FOOD, AND ENERGY-INTAKE OF THE GOLDEN SPINY MOUSE (ACOMYS RUSSATUS)

The golden spiny mouse, Acomys russatus, exists in the most arid and w arm habitats of Israel's Rift Valley. This species is nocturnally acti ve, but becomes diurnal when it coexists with the common spiny mouse, Acomys cahirinus. Therefore, we studied the responses of A. russatus t o changes in photoperiod. Daily rhythms of body temperature (T-b), app arent digestible dry matter intake (DDMI), gross digestible energy int ake (GDEI), water intake, and body mass were measured in A. russatus k ept at an ambient temperature of 28 degrees C, and acclimated to two d ifferent photoperiod regimes: 16L:8D (long photophase; LP-mice) and 8L :16D (long scotophase; LS-mice). In LS-mice, the duration of elevated T-b was longer than in LP-mice. DDMI, GDEI, and water intake were sign ificantly higher in LS-mice. No differences were recorded in body mass . The results of this study show that, as in other desert rodent speci es, thermoregulatory mechanisms of A. russatus respond to changes in p hotoperiod. Therefore, such changes may be used as cues for seasonal a cclimatization.