Refractoriness in Female Lizard Reproduction: A Probable Circannual Clock

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Science  29 Jul 1977:
Vol. 197, Issue 4302, pp. 495-497
DOI: 10.1126/science.197.4302.495


Postreproductive Cnemidophorus uniparens maintained under free-running conditions of constant darkness for 7 months became reproductive at the same time as controls exposed to a long photoperiod. This lizard exhibits a pause in reproductive activity (refractory period) commencing in late summer in nature and terminating in mid-December in captivity. Both groups terminated refractoriness and started reproducing simultaneously in December despite maintenance of the experimental group in darkness since September. These results confirm the hypothesis that the refractory period in this lizard is under endogenous control.