Influence of Temperature and Photoperiod on the Annual Ovarian Cycle in the Lizard Anolis carolinensis

Female Anolis carolinensis resemble males of the species in showing some dependence on both photoperiod and temperature for the regulation of seasonal reproductive activity. In both sexes, photoperiodism is a transient seasonal phenomenon and high temperatures appear to be one of the major stimuli for the onset of gonadal activity in the spring. Development of ovaries may require higher temperatures than the testes, helping to insure that males will be reproductively mature before egg production begins. Sperm retention is effective in female A. carolinensis but seems to be relatively inefficient for fertilizing eggs produced more than a few months after copulation. Unlike the males, females do not appear to have the potential for continuous reproductive activity: ovarian regression could not be prevented by manipulation of photoperiod and temperature. Also, females show a more marked refractoriness to photo-thermal stimulation in fall. In these respects, female A. carolinensis differ from females of tropical congeneric species; instead, they resemble temperate-zone lizards that have been studied. Photoperiod and temperature appear to be only two of several important exogenous stimuli that regulate the timing of seasonal changes in ovarian activity; moisture and social interactions are probably also important.