A comparative study of stress physiology in the common watersnake (Nerodia sipedon), the diamondback watersnake (Nerodia rhombifer), and the queen snake (Regina septemvittata).

Abstract

Vertebrates respond to stressors in part by increasing the secretion of glucocorticoids from the adrenal gland. Both intrinsic and extrinsic factors (e.g., age, sex, season) have been shown to influence glucocorticoid secretion within a species, but understanding of species differences in glucocorticoid secretory patterns is limited. In this study, I examined corticosterone, progesterone, and testosterone levels in the common watersnake (Nerodia sipedon), the diamondback watersnake (Nerodia rhombifer), and the queen snake (Regina septemvittata) at a capture baseline and in response to an acute 30 minute confinement stress. I also examined the same steroids in Nerodia sipedon subjected to three weeks of laboratory housing, a known chronic stressor. All three species exhibited elevated corticosterone in response to acute stress but baseline and post- stress levels varied among species. Overall, Nerodia sipedon and Nerodia rhombifer exhibited similar corticosterone and testosterone levels both at capture baseline and after 30 minutes of confinement stress. Regina septemvittata had substantially higher corticosterone levels than the two Nerodia species. Nerodia sipedon subjected to chronic stress showed no significant changes in corticosterone levels from the baseline to post-lab housing, suggesting downregulation of the hypothalamo-pituitary-adrenocortical axis and glucocorticoid production.