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Updated: Mar 6, 2026
Analysis of Circadian Photoresponses in Drosophila Using Locomotor Activity
Circadian activity patterns, photoperiodic responses and population cycles in voles : I. Long-term variations in
1Physiologische Ökologie, Zoologisches Institut der Universität Köln, Weyertal 119, D-5000, Köln 41, Federal Republic of Germany.
Abstract:
Patterns of above-ground activity were recorded in two free-ranging populations of Microtus agrestis (L.) and one population of M. arvalis (Pall.) over several years by means of passage counters. Long-term variations of the circadian patterns were observed, but did not repeat themselves in a 12-month cycle. Variations in all three populations could be described by a sinusoidal function of an 18-month period. Maxima and minima of the sine-function were connected to distinct photoperiods (equinoxes and solstices). In a cyclic North Swedish population, the sine-function was superimposed by a second function which shows saturation behaviour. The relevance of these findings is discussed with respect to vole population cycles.
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