Meeting Abstract

P2.137  Tuesday, Jan. 5  Heavy-bodied vs. Light-bodied – Does it Matter? Size Dependent Mate Selection and Pheromone Production in Garter Snakes LEMASTER, M.P.*; STEFANI, A.C.; MASON, R.T.; Western Oregon University; Western Oregon University; Oregon State University lemastm@wou.edu

Many populations of garter snakes live in regions that limit the ability of females to reproduce on an annual basis due to feeding constraints. Because courtship is very energetically expensive for male garter snakes, it would benefit males to be able to discriminate between females with high energy stores that will reproduce that year (i.e., ‘heavy-bodied” females) versus those females with low energy stores that will not reproduce (i.e., ‘light-bodied’ females). Utilizing the red-sided garter snake (Thamnophis sirtalis parietalis) as a model system, we first examined whether males can discriminate between heavy-bodied and light-bodied females during the breeding season. Results from courtship trials demonstrate that males indeed can differentiate among females based on body condition, preferring heavy-bodied females over light-bodied females. In addition, chemical analyses were performed to examine whether the female sexual attractiveness pheromone might be responsible for mediating the observed male preference. Comparisons of skin lipid samples from females of varying body conditions show that heavy-bodied females have a pheromone profile that is qualitatively different to that of light-bodied females. Together, these results support the hypothesis that male garter snakes are able to discriminate among females based on their potential reproductive output and suggest a role for the female sexual attractiveness pheromone in mediating this preference.