Environmental Control of Seasonal Reproduction in a Parthenogenetic Lizard Cnemidophorus uniparens

Publisher Website
Google Scholar
Abstract
Previous studies of the parthenogenetic whiptail lizard Cnemidophorus uniparens have provided the best evidence for an endogenous circannual rhythm of reproduction in a reptile. However, these studies were restricted to captive animals on constant photothermal conditions. We report the results of field and laboratory studies indicating that timing of reproduction is dramatically affected by seasonal temperature change. Our field data show that between-year variations in timing of breeding in natural populations are correlated with between-year variations in spring temperatures. Our laboratory data demonstrate that reproduction is delayed and synchronized by exposure to winter-like photothermal conditions. Thus, temperature appears to be the most important environmental cue regulating timing of reproduction in this species. However, the conclusion of previous studies that the natural reproductive cycle is controlled by a circannual rhythm is equivocal and requires further study.