Meeting Abstract

P2.14  Monday, Jan. 5  Temporal Variation in the Female Sexual Attractiveness Pheromone of the Red-sided Garter Snake, Thamnophis sirtalis parietalis LEMASTER, MP*; UHRIG, E; MASON, RT; Western Oregon University; Western Oregon University; Oregon State University lemastm@wou.edu

Female garter snakes produce and express a sexual attractiveness pheromone during the breeding season that elicits male courtship behavior. Composed of a homologous series of saturated and mono-unsaturated methyl ketones, this pheromone is expressed in the skin lipids of females. It has been observed that female snakes lose their attractivity to males as the breeding season progresses. Here we present a study designed to determine whether temporal changes in the quantity and / or quality of the female sexual attractiveness pheromone are responsible for the observed loss of attractivity utilizing the red-sided garter snake, Thamnophis sirtalis parietalis, as a model system. Female red-sided garter snakes were collected immediately following spring emergence and held under natural conditions (outdoor arenas) for the duration of the breeding season. Behavioral experiments demonstrated that females are significantly less attractive to males within two weeks of emergence from winter hibernacula. Subsequent chemical analyses revealed a significant qualitative difference in the relative concentrations of individual methyl ketones comprising the pheromone profiles between newly emerged females and females two weeks post-emergence. Together, these results support the hypothesis that changes in the female sexual attractiveness pheromone are responsible for diminishing post-emergence female attractivity in garter snakes.