Meeting Abstract
P2.2 Saturday, Jan. 5 The effect of mating with vasectomized males on subsequent mating behavior in female red-sided garter snakes. FRIESEN, C.R*; UHRIG, E.J.; MASON, R.T.; Oregon State University friesenc@science.oregonstate.edu
Female sexual promiscuity is prevalent in nature. One consequence of female sexual promiscuity is that male-male competition often continues post-copulation within the female’s reproductive tract. There are two central questions in the study of postcopulatory sexual selection. 1) What factors determine male fertilization success? 2) Why do females mate with multiple males? Explanations of female promiscuity propose that indirect benefits (genetic; good genes, and bet hedging etc.), and/or direct benefits (e.g., extra paternal care, obscuring paternity in social groups etc.) to females outweigh the costs of female promiscuity (e.g., increased predation risk, and exposure to STDs etc.). One hypothesized direct benefit is fertilization insurance; that is females remate to ensure they have sperm to fertilize their eggs. We tested whether female remating frequency was affected by mating with a sperm-depleted male. Our results indicate that when female red-sided garter snakes (Thamnophis sirtalis parietalis) mate with a vasectomized male, they are more likely to remate in semi-natural arenas. These males still produced a copulatory plug, but did not deliver sperm during mating. There are two non-mutually exclusive hypotheses that may account for our results. 1) Females can sense sperm stores within the reproductive tract and use this information to evaluate the quality of a recent mate and remate if they were sperm depleted. 2) The seminal fluid contains a substance(s) that affects female receptivity to subsequent matings. These hypotheses are intriguing as the first suggests a form of cryptic female choice in which females remate after mating with a suboptimal male and the second suggests sexual conflict in which males manipulate females to ensure their own reproductive success.
