DAILY RHYTHMS OF BODY-TEMPERATURE IN ACOMYS-RUSSATUS - THE RESPONSE TO CHEMICAL SIGNALS RELEASED BY ACOMYS-CAHIRINUS

Two species of spiny mice of the genus Acomys-the golden spiny A. russ atus and the common spiny A. cahirinus-are sympatric in the arid and h ot parts of the Rift Valley in Israel. The coexistence of these two sp ecies is due to exclusion of A. russatus mice by A. cahirinus mice fro m nocturnal activity. The aim of this research was to study if odor si gnals released by A. cahirinus mice can play a role in the exclusion o f A. russatus mice. A. russatus mice with an implanted transmitter rec ording body temperature (T(b)) were kept alone in a metabolic chamber under constant conditions of ambient temperature (27-degrees-C) and ph otoperiod (12 h light: 12 h dark). After 5 days of recording, chemical signals from an A. cahirinus mouse were added through the air tube go ing into the metabolic chamber of the A. russatus mice. This treatment caused a shift of approximately 2 h in T(b) daily rhythm of the naive tested A. russatus mice, whereas no shift was observed in A. russatus mice that had been kept in the same room with the A. cahirinus mouse before measurements. These results strongly support the idea that chem ical signals released by A. cahirinus mice can entrain the T(b) rhythm s of A. russatus mice. Therefore, it may be assumed that the exclusion of A. russatus mice from nocturnal activity by A. cahirinus mice coul d be achieved through the odor released by the latter.