Cyclic fluctuations of microtine populations: half a century of research

Numerous microtine populations show important cyclic fluctuations of densit y which have aroused many scientific works, mostly since the fifties. Intri nsic mechanisms (density-dependence, genetic selection) and extrinsic mecha nisms (predation, interaction with trophic resources) were both involved fo r building hypotheses. The present paper gives a survey of the different in vestigations developed in this field and a review of the mechanisms suppose dly involved in population fluctuations. As a conclusion we try to build a synthetic diagram showing the place and the role of the various regulating factors, and their interactions.