Meeting Abstract
In species with limited opportunities for reproduction and feeding, females are generally unable to recover sufficient energy stores to reproduce in consecutive years. Body condition has been used as a proxy for recent reproductive history in such species. We showed that hormonal responses to capture stress and receptivity to mating vary with body condition in female red-sided garter snakes (Thamnophis sirtalis), a species with limited breeding opportunities. These data suggest that reproductive history influences both stress responsiveness and mating behavior, although no study has directly examined if body condition accurately predicts reproductive history. We hypothesized that females that did not give birth during the previous summer would have higher body condition, lower stress responsiveness, and higher likelihood of mating during the spring breeding season. We collected unmated females and measured hormonal responses to capture stress and recorded latency to copulate for each female. Mated females were then housed in the lab to determine which females became parturient over the summer. Mated females that did not give birth were assumed to have given birth the previous summer and were deemed post-parturient. We found that parturient and post-parturient females did not differ significantly in body condition or hormonal stress responses, but parturient females mated more quickly. We also found that receptive females had a smaller stress response, were more likely to be in positive body condition, and were more likely to give birth than unreceptive females. These data suggest that variation in the sensitivity of the hypothalamus-pituitary-adrenal axis is related more to reproductive history than body condition and may contribute to reproductive “decision making.”
