title: Female behaviour and the interaction of male and female genital traits mediate sperm transfer during mating.
abstract: Natural selection and post-copulatory sexual selection, including sexual conflict, 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 (Thamnophis sirtalis parietalis) reveal that copulation duration and 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 behaviour during copulation. By mating females with anesthetized cloacae to males with spine-ablated hemipenes using a fully factorial design, we identified significant female-male copulatory trait interactions and found that females prevent sperm from entering their oviducts by contracting their vaginal pouch. Furthermore, these muscular contractions limit copulatory plug size, whereas 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 outcomes.
authors.affiliation: Department of Integrative Biology, Oregon State University, Corvallis, OR, USA.|School of Life and Environmental Sciences, University of Sydney, Sydney, NSW, USA.
authors.forename: C R
authors.initials: CR
authors.lastname: Friesen
authors.affiliation: Department of Integrative Biology, Oregon State University, Corvallis, OR, USA.
authors.forename: E J
authors.initials: EJ
authors.lastname: Uhrig
authors.affiliation: Department of Integrative Biology, Oregon State University, Corvallis, OR, USA.
authors.forename: R T
authors.initials: RT
authors.lastname: Mason
authors.affiliation: Department of Biological Sciences, 104 Clapp Laboratory, Mount Holyoke College, South Hadley, MA, USA.
authors.forename: P L R
authors.initials: PL
authors.lastname: Brennan
mesh_terms: D000818:Animals; D003307:Copulation; D005260:Female; D005836:Genitalia, Female; D005837:Genitalia, Male; D008297:Male; D012098:Reproduction; D012726:Sexual Behavior, Animal; D012911:Snakes; D013094:Spermatozoa
keywords: copulation duration; copulatory plugs; female genitalia; garter snakes; genital coevolution; hemipene; sexual conflict; sexual selection; sperm transfer