title: Diverse dose-response effects of yolk androgens on embryo development and nestling growth in a wild passerine.
abstract: Avian egg yolks contain various amounts of maternally derived androgens that can modify offspring phenotype and adjust their development to the post-hatching environment. Seemingly adaptive variation in yolk androgen levels with respect to breeding density conditions or male attractiveness has been found in numerous studies. One important consideration that has been overlooked in previous research is the likely non-linear nature of hormone effects. To examine possible complex dose-response effects of maternal androgens on chick development, we experimentally administered three different androgen doses of the naturally occurring mixture of yolk testosterone and androstenedione to spotless starling eggs (Sturnus unicolor). We found that yolk androgens induce a non-linear dose-response pattern in several traits. Androgens had a stimulatory effect on hatchling body mass and nestling skeletal growth, but maximum values were found at intermediate doses, whereas our highest dose resulted in a decrease. However, the opposite U-shaped effect was found on nestling body mass. We also detected linear negative and positive effects on embryonic development period and nestling gape width, respectively. Our results suggest differential tissue responsiveness to yolk androgens, which may result in compromises in maternal allocation to produce adapted phenotypes. Because of the non-linear dose-response pattern, future investigations should carefully consider a wide range of concentrations, as the balance of costs and benefits may strongly differ depending on concentration.
authors.affiliation: Departamento de Ecología Evolutiva, Museo Nacional de Ciencias Naturales (MNCN-CSIC), José Gutiérrez Abascal 2, Madrid E-28006, Spain Jaime.muriel@mncn.csic.es.
authors.forename: Jaime
authors.initials: J
authors.lastname: Muriel
authors.affiliation: Departamento de Ecología Evolutiva, Museo Nacional de Ciencias Naturales (MNCN-CSIC), José Gutiérrez Abascal 2, Madrid E-28006, Spain Departamento de Ecología Evolutiva, Estación Biológica de Doñana (EBD-CSIC), Avda. Américo Vespucio, s/n, Isla de la Cartuja, Sevilla 41092, Spain.
authors.forename: Lorenzo
authors.initials: L
authors.lastname: Pérez-Rodríguez
authors.affiliation: Departamento de Fisiología Animal II, Facultad de Ciencias Biológicas, Universidad Complutense, José Antonio Novais, 2 Ciudad Universitaria, Madrid 28040, Spain.
authors.forename: Marisa
authors.initials: M
authors.lastname: Puerta
authors.affiliation: Departamento de Ecología Evolutiva, Museo Nacional de Ciencias Naturales (MNCN-CSIC), José Gutiérrez Abascal 2, Madrid E-28006, Spain.
authors.forename: Diego
authors.initials: D
authors.lastname: Gil
mesh_terms: D000728:Androgens / Q000378:metabolism / Q000494:pharmacology*; D000735:Androstenedione / Q000378:metabolism / Q000494:pharmacology*; D000818:Animals; D000831:Animals, Newborn; D001835:Body Weight / Q000187:drug effects; D001846:Bone Development / Q000187:drug effects; D004305:Dose-Response Relationship, Drug; D004530:Egg Yolk / Q000737:chemistry / Q000378:metabolism; D047108:Embryonic Development / Q000187:drug effects; D005260:Female; D008297:Male; D010641:Phenotype; D046749:Starlings / Q000196:embryology* / Q000254:growth & development* / Q000378:metabolism; D013739:Testosterone / Q000378:metabolism / Q000494:pharmacology*
chemical_list: D000728:Androgens; D013739:Testosterone; D000735:Androstenedione
keywords: Androstenedione; Developmental plasticity; Hormone transfer; Maternal effects; Sturnus unicolor; Testosterone