title: Variability in sperm form and function in the context of sperm competition risk in two Tupinambis lizards.
abstract: In polyandrous species, sperm morphometry and sperm velocity are under strong sexual selection. Although several hypotheses have been proposed to explain the role of sperm competition in sperm trait variation, this aspect is still poorly understood. It has been suggested that an increase in sperm competition pressure could reduce sperm size variation or produce a diversity of sperm to maximize male fertilization success. We aim at elucidating the variability of sperm morphometric traits and velocity in two Tupinambis lizards in the context of sperm competition risk. Sperm traits showed substantial variation at all levels examined: between species, among males within species, and within the ejaculate of individual males. Sperm velocity was found to be positively correlated with flagellum: midpiece ratio, with relatively longer flagella associated with faster sperm. Our results document high variability in sperm form and function in lizards.
authors.affiliation: Laboratorio de Biología del Comportamiento, Facultad de Ciencias Exactas, Físicas y Naturales, Instituto de Diversidad y Ecología Animal (IDEA) CONICET, Universidad Nacional de Córdoba Av. Vélez Sársfield 299, X5000JJC, Córdoba, Argentina.
authors.forename: Cecilia S
authors.initials: CS
authors.lastname: Blengini
authors.affiliation: Laboratorio de Biología del Comportamiento, Facultad de Ciencias Exactas, Físicas y Naturales, Instituto de Diversidad y Ecología Animal (IDEA) CONICET, Universidad Nacional de Córdoba Av. Vélez Sársfield 299, X5000JJC, Córdoba, Argentina.
authors.forename: Naretto
authors.initials: N
authors.lastname: Sergio
authors.affiliation: Laboratorio de Biología del Comportamiento, Facultad de Ciencias Exactas, Físicas y Naturales, Instituto de Diversidad y Ecología Animal (IDEA) CONICET, Universidad Nacional de Córdoba Av. Vélez Sársfield 299, X5000JJC, Córdoba, Argentina.
authors.forename: Cardozo
authors.initials: C
authors.lastname: Gabriela
authors.affiliation: Centro de Biología Celular y Molecular, Facultad de Ciencias Exactas, Físicas y Naturales, Instituto de Investigaciones Biológicas y Tecnológicas (IIByT) CONICET, Universidad Nacional de Córdoba Av.Velez Sarsfield 1611, X5016GCA, Córdoba, Argentina.
authors.forename: Laura C
authors.initials: LC
authors.lastname: Giojalas
authors.affiliation: Laboratorio de Biología del Comportamiento, Facultad de Ciencias Exactas, Físicas y Naturales, Instituto de Diversidad y Ecología Animal (IDEA) CONICET, Universidad Nacional de Córdoba Av. Vélez Sársfield 299, X5000JJC, Córdoba, Argentina.
authors.forename: Chiaraviglio
authors.initials: C
authors.lastname: Margarita
keywords: Postcopulatory sexual selection; Squamata; sperm evolution; sperm morphometry; sperm velocity