title: Effects of testosterone on morphology, performance and muscle mass in a lizard.
abstract: Because sexual selection pressures are high in sexually dimorphic organisms, morphological, physiological and performance traits are often studied in a sexual selection context. The proximate mechanisms underlying evolutionary change in these traits, however, remain largely unstudied. Here, we examined the role of steroids in shaping morphology and physiological performance in males of a sexually dimorphic lizard (Gallotia galloti). We compared morphology and physiological performance of males with experimentally elevated testosterone levels to sham-operated males. Before surgery, inter-individual variation in plasma testosterone levels correlated positively with bite force capacity. Administration of exogenous testosterone resulted in an increase of the mass of both jaw closing and locomotory muscles compared with sham-operated individuals, but the responsiveness varied considerably among muscle groups. In contrast to our expectations, the dramatic testosterone-induced changes in muscle masses did not result in concordant changes in bite force performance or sprint speed.
authors.affiliation: Department of Biology, University of Antwerp, Antwerp, Belgium. katleen.huyghe@ua.ac.be
authors.forename: Katleen
authors.initials: K
authors.lastname: Huyghe
authors.forename: Jerry F
authors.initials: JF
authors.lastname: Husak
authors.forename: Ignacio T
authors.initials: IT
authors.lastname: Moore
authors.forename: Bieke
authors.initials: B
authors.lastname: Vanhooydonck
authors.forename: Raoul
authors.initials: R
authors.lastname: Van Damme
authors.forename: Miguel
authors.initials: M
authors.lastname: Molina-Borja
authors.forename: Anthony
authors.initials: A
authors.lastname: Herrel
mesh_terms: D000818:Animals; D001732:Bite Force; D008116:Lizards / Q000033:anatomy & histology / Q000502:physiology*; D008297:Male; D053580:Muscle Strength / Q000187:drug effects / Q000502:physiology; D018482:Muscle, Skeletal / Q000033:anatomy & histology / Q000187:drug effects / Q000502:physiology*; D010413:Penis / Q000033:anatomy & histology / Q000187:drug effects / Q000502:physiology; D013739:Testosterone / Q000097:blood / Q000494:pharmacology* / Q000502:physiology
chemical_list: D013739:Testosterone