Induced ovulation: Effects of sexual behavior and insemination on ovulation and progesterone levels in Taricha granulosa

Abstract

Gravid female rough-skinned newts ( Taricha granulosa) were captured prior to contact with males and maintained in simulated pond conditions. Only females exposed to male courtship and insemination ovulated during the experiments, as indicated by ova in the oviducts. Ovulation was not observed in females that were prevented from being inseminated by nuptial males. None of the females isolated from males exhibited signs of ovulation. Progesterone concentrations were highest at the onset of the breeding season. Among the inseminated females, plasma progesterone concentrations were highest in those females that possessed oviducal eggs. In addition to documenting induced ovulation in these newts, this study clarified several aspects of the reproductive pattern in T. granulosa.