Meeting Abstract
132.6 Monday, Jan. 7 Body condition modulates responses to capture stress and exogenous corticosterone in female red-sided garter snakes. DAYGER, CA*; CEASE, AJ; LUTTERSCHMIDT, DI; Portland State Univ, OR; Univ of Sydney, Australia; Portland State Univ, OR cdayger@pdx.edu
Many studies have examined the role of corticosterone (CORT) in male reproduction, but relatively little is known about how CORT affects female mating behavior. We treated female red-sided garter snakes (Thamnophis sirtalis parietalis) with capture stress during the spring mating season in Manitoba, Canada. Blood samples were collected before (0h), during (2h) and after (4h) capture stress treatment. Stress-treated and control females were then placed individually in an arena containing 20 males and latency to copulate was recorded. Body condition was determined as the residual from a regression of body mass on snout-vent-length. Capture stress significantly increased plasma CORT (p=0.025). However, only females with negative body condition exhibited increased CORT after 2 hours of capture stress (p=0.043). Importantly, baseline CORT did not differ between females with negative or positive body conditions, suggesting that differences in hormonal stress responses were related to differences in hypothalamus-pituitary-adrenal axis sensitivity. Similar to previous results in male red-sided garter snakes, capture stress did not influence mating behavior (p=0.090). These results suggest that females may also be behaviorally resistant to capture stress during the mating season. However, in a second experiment, exogenous CORT (15 or 60 μg) significantly increased latency to copulate (p=0.010). Interestingly, only females with negative body condition responded to the lower CORT dose, suggesting that glucocorticoid receptor sensitivity and/or density varies with body condition. Collectively, our results indicate that female body condition modulates hormonal and behavioral responses to elevated CORT during their short mating season.
