73.4 Friday, Jan. 6 Chemical Ecology of the Red-spotted Garter Snake, Thamnophis sirtalis concinnus UHRIG, E.J.*; LEMASTER, M.P.; MASON, R.T.; Oregon State University, Corvallis; Western Oregon University, Monmouth; Oregon State University, Corvallis email@example.com
To date, most studies of garter snake chemical ecology have focused on the female sexual attractiveness pheromone of the red-sided garter snake (Thamnophis sirtalis parietalis). This pheromone, identified as a series of methyl ketones sequestered within the skin lipids of females, elicits male reproductive behaviors during the breeding season. In the current study, we demonstrate that female skin lipids of another Thamnophis sirtalis subspecies, the red-spotted garter snake (T. s. concinnus), contain methyl ketones similar to those produced by red-sided garter snakes. The ability of male red-spotted garter snakes to detect and follow trails composed of isolated female methyl ketones is further evidence that the reproductive role of these compounds is not limited to the red-sided garter snake system. Comparisons of red-spotted and red-sided garter snake pheromone profiles indicate that the relative concentrations of individual methyl ketones differ between subspecies. This variation, however, is apparently not great enough to preclude inter-subspecific courtship behavior. We also examine whether the red-spotted garter snake pheromone exhibits annual variation or, as occurs in red-sided garter snakes, variation based on female body size. Comparing the chemical ecology of these two subspecies, the red-spotted garter snake and the red-sided garter snake, is of particular interest as they have somewhat disparate life histories despite their close phylogenetic relationship.