title: Yolk androgens do not appear to mediate sexual conflict over parental investment in the collared flycatcher Ficedula albicollis.
abstract: Males and females are in conflict over parental care, as it would be favourable for one parent to shift labour to the other. Yolk hormones may offer a mechanism through which female birds could influence offspring traits in ways that increase the relative investment by the male. We studied the role of yolk androgens in mediating sexual conflict over parental care in the collared flycatcher (Ficedula albicollis). In a cross-fostering experiment, the male's proportion of total feeding visits increased with increasing androgen levels in the foster eggs. This could suggest that sexual conflict over parental care may be influenced by the female's differential allocation of yolk androgens or a maternal effect associated with yolk androgens. However, when we experimentally elevated yolk androgen levels, male feeding rates did not differ between control and androgen-manipulated nests. This suggests that other egg components correlated with yolk androgen levels, rather than yolk androgen levels per se, may influence male parental effort. In conclusion, yolk androgens per se do not appear to mediate sexual conflict over parental investment in the collared flycatcher.
authors.affiliation: Department of Biology, University of Turku, Turku, Finland. suvi.ruuskanen@utu.fi
authors.forename: Suvi
authors.initials: S
authors.lastname: Ruuskanen
authors.forename: Blandine
authors.initials: B
authors.lastname: Doligez
authors.forename: Barbara
authors.initials: B
authors.lastname: Tschirren
authors.forename: Natalia
authors.initials: N
authors.lastname: Pitala
authors.forename: Lars
authors.initials: L
authors.lastname: Gustafsson
authors.forename: Ton G G
authors.initials: TG
authors.lastname: Groothuis
authors.forename: Toni
authors.initials: T
authors.lastname: Laaksonen
mesh_terms: D000728:Androgens / Q000378:metabolism; D000735:Androstenedione / Q000378:metabolism*; D000818:Animals; D000835:Animals, Wild; D004530:Egg Yolk / Q000378:metabolism*; D005247:Feeding Behavior / Q000502:physiology; D005260:Female; D008297:Male; D008425:Maternal Behavior / Q000502:physiology*; D009425:Nesting Behavior / Q000502:physiology*; D046109:Passeriformes; D010332:Paternal Behavior; D011863:Radioimmunoassay; D013739:Testosterone / Q000378:metabolism*
chemical_list: D000728:Androgens; D013739:Testosterone; D000735:Androstenedione