Photoperiodic control of reproduction in the male lizardAnolis carolinensis |
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Authors: | Herbert Underwood Douglas Hall |
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Institution: | (1) Department of Zoology, North Carolina State University, 27650 Raleigh, North Carolina, USA;(2) Present address: Grainger Laboratory Inc., 709 W. Johnson St., 27603 Raleigh, North Carolina, USA |
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Abstract: | Summary In contrast to the higher vertebrates the photoperiodic time measuring system in the male lizardAnolis carolinensis seems to rely on an hourglass timer which lacks endogenous rhythmicity. This timer appears to measure the absolute length of the light portion of light-dark (LD) cycles. The present study further characterized the nature of theAnolis photoperiodic timer and demonstrated: (1) The gonadal response is quite sensitive to photostimulation. Exposure to as few as three 16 h photoperiods (over a 3 week period) can maintain testicular function in summer anoles whereas exposure to as few as six 16 h photoperiods (over a 3 week period) can elicit maximal testicular development in the fall. (2) The photoperiodic timer does not have to be reset daily by a dark interruption. (3) The dark portion of LD cycles may be involved in a complex fashion in reversing a light-initiated reaction and (4) Comparisons of entrained circadian activity rhythms with testicular responses to various light cycles argue against the participation of a circadian clock in photoperiodic time measurement.Abbreviation
CRPP
circadian rhythm of photoperiodic photo-sensitivity |
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