Meeting Abstract
Male red-sided garter snakes (Thamnophis sirtalis parietalis) rely on a female sexual attractiveness pheromone to exhibit reproductive behavior during the breeding season. Prior research indicates that pheromone expression in the skin lipids of females occurs during winter dormancy and suggests a regulatory role for estrogen in this process. Here we present a study designed to parse out when in the dormancy period females begin to express the sexual attractiveness pheromone and to what extent estrogen may influence the timing of this event. To this end, we collected skin lipid extracts from female snakes during fall prehibernation and three time points during hibernation: 4, 8, and 16 weeks. At each time point, females were treated with either peanut oil (control) or estrogen for six days preceding skin lipid extraction. During the mating season, we then presented the samples to courting males using a Y-maze. Samples from each time period and treatment were presented in conjunction with skin lipid extracts from spring-collected, attractive females to determine whether males could differentiate between the two trail types. Results demonstrate that males prefer to follow trails from spring-collected females compared to peanut oil-treated females up through 4 weeks into winter dormancy, but lose the ability to discriminate between the two trail types once females have been in winter dormancy for 8 weeks. However, when presented with estrogen-treated female skin lipid trails, males lose the ability to discriminate between trail types after females have been in winter dormancy for only 4 weeks. These results suggest that pheromone expression begins during the second month in winter dormancy for female red-sided garter snakes, with the underlying mechanism becoming sensitive to estrogen within the first month.
