Abstract
Courtship song in Drosophila is produced by the male's wing vibration and consists of pulses of tone produced at intervals of approximately 34 msec in D. melanogaster and 48 msec in D. simulans. We have observed that the intervals between these pulses are not constant but fluctuate rhythmically with periods of approximately 1 min in D. melanogaster and 0.5 min in D. simulans. In D. melanogaster, three allelic per mutations have been isolated which affect the periodicity of the circadian oscillators affecting both eclosion and locomotor activity [Konopka, R. & Benzer S. (1971) Proc. Natl. Acad. Sci. USA 68, 2112-2116]. Each of the per alleles--pers, which shortens the circadian period, perI, which lengthens it, and perO, which abolishes it--strikingly affects the 60-sec song rhythm in a parallel fashion. Therefore, both circadian rhythms and a very short, noncircadian oscillation appear to be influenced by the same gene.