Entrainment and phase shifts in frugivorous bats (Rousettus leschenaulti): Effect of light in roosts

Abstract

Whether the differential exposure to light intensity in roosts affected the entrainment and phase response curves (PRCs) for the circadian flight activity rhythm was investigated in two roosts of Rousettus leschenaulti bats. Bats from the dark roost (BDR) experienced complete darkness while those from the lighted roost (BLR) experienced bright light during the day. When entrained by LD 12:12 cycles, the BDR had less negative phase angle difference (Ψ), long duration of activity phase (α) while the BLR had more negative Ψ and short α. Period of the free-running rhythm in constant darkness was shorter in the BDR than that in the BLR. The PRC for the BDR had a high amplitude, a dead zone of 2 h and the ratio of advance to delay area (A/D) < 1; while the PRC for the BLR had a low amplitude, a dead zone of 8 h and A/D > 1.

Keywords:

• Entrainment
• phase response curve
• Rousettus leschenaulti

Acknowledgements

These studies are supported by the Research Grant No. 14/14/2000-ERS/RE funded by the Ministry of Environment and Forest, New Delhi to DSJ.