Reproductive Seasonality of Three Cold-temperate Viviparous Skinks from Southeastern Australia

Abstract

Reproductive cycles and patterns of sperm storage were examined for three regionally sympatric species of cold-temperate viviparous Australian skinks previously reported to have Type II reproductive cycles (autumn spermatogenesis and mating, with oviductal sperm storage (OSS) and spring ovulation). Histological examination of oviducts, testes and epididymides of winter- and spring-collected skinks were combined with data on monthly variation in gonad size (ovarian follicle diameter and testis length) obtained from museum specimens. Pseudemoia entrecasteauxii exhibited autumn spermatogenesis and mating, OSS over winter, and spring vitellogenesis and ovulation, concurring with previous studies for more southern populations. In contrast to previous studies from more southern populations, Niveoscincus coventryi and Hemiergis decresiensis displayed autumn spermatogenesis with epididymal sperm storage (ESS) over winter and spring vitellogenesis, mating and ovulation. Timing of mating and sperm storage patterns may vary geographically or possibly be plastic in response to local or annual variation in environmental factors. Autumn-onset vitellogenesis with OSS is hypothesized to be the optimal cycle for producing offspring earlier in the breeding season.