Long-Term Effects of Constant Photoperiods on Testicular Cycles of White-Crowned Sparrows (Zonotrichia leucophrys gambelii)
- 1 October 1976
- journal article
- research article
- Published by University of Chicago Press in Physiological Zoology
- Vol. 49 (4) , 407-416
- https://doi.org/10.1086/physzool.49.4.30155703
Abstract
White-crowned sparrows (Zonotrichia leucophrys gambelii) kept on constant photoperiods of LD 8:16, LD 16:8, and LD 24:0 for up to 2½ years showed no signs of a recurrent cycle of testicular growth and regression. Photoperiodic tests at the end of long-term confinement showed that the normal gonadal responses to photostimulation were unimpaired. No evidence of an endogenous (circannual) cycle of reproductive function was found in this species even in constant light (LD 24:0). Alternatives to the endogenous-rhythm theory in the timing of annual cycles are discussed.This publication has 3 references indexed in Scilit:
- Cycles of fat deposition and molt in white-crowned sparrows in constant environmenal conditionsComparative Biochemistry and Physiology, 1968
- The Photorefractory Period of the House FinchEcology, 1968
- Regulation of refractory period in the photoperiodic responses of the white‐throated sparrowJournal of Experimental Zoology, 1958