Meeting Abstract
Natural selection, sexual selection and sexually antagonistic coevolution contribute to genital diversification. Fundamental first steps in understanding how these processes shape the evolution of specific genital traits are to determine their function experimentally and to understand the interactions between female and male genitalia during copulation. Our experimental manipulations of male and female genitalia in red-sided garter snakes reveal that copulation duration, copulatory plug deposition, as well as total and oviductal/vaginal sperm counts are influenced by the interaction between male and female genital traits and female behavior during copulation. By mating females with anesthetized cloacae to males with spine-ablated hemipenes, we identified significant female-male copulatory interactions and found that females prevent sperm from entering their oviducts by contracting their vaginal pouch. Furthermore, these muscular contractions limit copulatory plug size, while the basal spine of the male hemipene aids in sperm and plug transfer. Our results are consistent with a role of sexual conflict in mating interactions and highlight the evolutionary importance of female resistance to reproductive control.
