title: The seminal coagulum favours passage of fast-moving sperm into the uterus in the black-handed spider monkey.
abstract: In addition to gametes, mammalian internal fertilisation has required the evolution of assorted anatomical, physiological and biochemical devices to deal with intra- and inter-sexual conflict such as sperm competition and female cryptic choice respectively. The seminal coagulum of primates and other mammals is viewed as one of such devices. Among primates, the seminal coagulum characteristically occurs in multi-male and multi-female species, leading us to suppose that it intervenes in sperm competition. However, it can also provide cues to the female reproductive tract about male desired or undesired traits, and therefore deter or favour sperm survival and migration. The present work investigates whether the seminal coagulum of the black-handed spider monkey enhances sperm fertilisation chances by improving the female reproductive tract conditions, and if the female reproductive tract is 'blind' to semen or behaves selectively towards ejaculates of different males. A series of artificial inseminations were done in five females, using the ejaculates of three different males, one at a time, and measuring the presence of distinct types of sperm inside the uteri at 10, 30 and 60 min following the insemination. The presence of coagulum, menstrual phase, and male and female identity only affected fast, straight-moving sperm, with larger amounts of fast sperm appearing inside the uteri when ejaculates had seminal coagulum, as well as when in the periovulatory phase. There was great intra-uterine fast-sperm variation regarding which male's semen inseminated which female. The results provide evidence to account for sexual conflict in the spider monkey as well as a methodological approach to this kind of study.
authors.affiliation: Departamento de Etología, Dirección de Neurociencias, Instituto Nacional de Psiquiatría Ramón de la Fuente Muñiz, Calzada México-Xochimilco 101, Col. San Lorenzo Huipulco, Tlalpan 14370, Mexico DF, Mexico.
authors.forename: Leonor
authors.initials: L
authors.lastname: Hernández-López
authors.forename: Ana Lilia
authors.initials: AL
authors.lastname: Cerda-Molina
authors.forename: Denisse L
authors.initials: DL
authors.lastname: Páez-Ponce
authors.forename: Ricardo
authors.initials: R
authors.lastname: Mondragón-Ceballos
mesh_terms: D000818:Animals; D053819:Atelinae / Q000502:physiology*; D001831:Body Temperature; D003163:Competitive Behavior; D030762:Estrous Cycle / Q000502:physiology; D005260:Female; D006863:Hydrogen-Ion Concentration; D007315:Insemination, Artificial / Q000379:methods; D008297:Male; D012661:Semen / Q000502:physiology*; D012726:Sexual Behavior, Animal; D013081:Sperm Motility / Q000502:physiology; D013094:Spermatozoa / Q000502:physiology*; D014621:Vagina / Q000502:physiology