Evidence for ecological adaptation of circadian systems

Summary Comparative studies on the circadian activity rhythm of five neotropical bat species show, that even exclusively tropical Chiroptera yield considerable differences with respect to their light-induced variation of the period length and the time needed for re-entrainment after phase shifts of the Zeitgeber-LD (Figs. 2 and 3). Species with a wide variation range of the period length resynchronize very fast and vice versa. Both reactions suggest the circadian system to have a higher plasticity or a higher sensibility for the exogenous components respectively. The sensibility for these exogenous components is, according to the hitherto results, in general higher within insectivorous Chiroptera species than within frugivorous/nectarivorous to omnivorous species. It is discussed, whether this can be interpreted as a specific adaptation to the demands of a predatory way of life.Dedicated to Prof. Dr. F.P. Möhres on the occasion of his 65th birthdayThis work was supported by the Deutsche Forschungsgemeinschaft (Er 59/1-5)