title: Yolk androgen deposition without an energetic cost for female rockhopper penguins: a compensatory strategy to accelerate brood reduction?
abstract: Whether androgen deposition in eggs is physiologically costly for female birds has remained a crucial but unsolved question, despite a broad use of this assumption in functional studies. We tested whether females depositing high androgen concentrations experienced higher mass losses than females depositing low androgen concentrations. Analysing female body mass change during egg formation in rockhopper penguins (Eudyptes chrysocome chrysocome), we observed no energetic cost to androgen deposition. Nevertheless, lighter females laid eggs with higher yolk androgen concentrations. This relationship existed only for the second-laid egg (B-egg), but not for the first-laid egg (A-egg). Since the B-egg is usually the first to hatch and the only one to produce a fledging chick, we hypothesize that differential yolk androgen deposition may be an adaptive strategy for females to affect brood reduction.
authors.affiliation: Max Planck Institute for Ornithology, 78315 Radolfzell, Germany. maud.poisbleau@ua.ac.be
authors.forename: Maud
authors.initials: M
authors.lastname: Poisbleau
authors.forename: David
authors.initials: D
authors.lastname: Carslake
authors.forename: Laurent
authors.initials: L
authors.lastname: Demongin
authors.forename: Marcel
authors.initials: M
authors.lastname: Eens
authors.forename: Olivier
authors.initials: O
authors.lastname: Chastel
authors.forename: Petra
authors.initials: P
authors.lastname: Quillfeldt
mesh_terms: D000818:Animals; D004530:Egg Yolk / Q000737:chemistry*; D004734:Energy Metabolism; D005260:Female; D008297:Male; D046429:Spheniscidae / Q000502:physiology*; D013739:Testosterone / Q000032:analysis*
chemical_list: D013739:Testosterone