title: Corticosterone regulates multiple colour traits in Lacerta [Zootoca] vivipara males.
abstract: Ornamental colours usually evolve as honest signals of quality, which is supported by the fact that they frequently depend on individual condition. It has generally been suggested that some, but not all types of ornamental colours are condition dependent, indicating that different evolutionary mechanisms underlie the evolution of multiple types of ornamental colours even when these are exhibited by the same species. Stress hormones, which negatively affect condition, have been shown to affect colour traits based on different pigments and structures, suggesting that they mediate condition dependence of multiple ornament types both among and within individuals. However, studies investigating effects of stress hormones on different ornament types within individuals are lacking, and thus, evidence for this hypothesis is scant. Here, we investigated whether corticosterone mediates condition dependence of multiple ornaments by manipulating corticosterone levels and body condition (via food availability) using a two-factorial design and by assessing their effect on multiple colour traits in male common lizards. Corticosterone negatively affected ventral melanin- and carotenoid-based coloration, whereas food availability did not affect coloration, despite its significant effect on body condition. The corticosterone effect on melanin- and carotenoid-based coloration demonstrates the condition dependence of both ornaments. Moreover, corticosterone affected ventral coloration and had no effect on the nonsexually selected dorsal coloration, showing specific effects of corticosterone on ornamental ventral colours. This suggests that corticosterone simultaneously mediates condition dependence of multiple colour traits and that it therefore accounts for covariation among them, which may influence their evolution via correlational selection.
authors.affiliation: Department of Ecology and Evolution, University of Lausanne, Lausanne, Switzerland; Department of Biodiversity and Evolutionary Biology, Museo Nacional de Ciencias Naturales (MNCN-CSIC), Madrid, Spain; Instituto Pirenaico de Ecología (IPE-CSIC), Jaca, Spain.
authors.forename: L M
authors.initials: LM
authors.lastname: San-Jose
authors.forename: P S
authors.initials: PS
authors.lastname: Fitze
mesh_terms: D000818:Animals; D001066:Appetite; D003116:Color; D003345:Corticosterone / Q000502:physiology*; D005247:Feeding Behavior; D008116:Lizards / Q000502:physiology*; D008297:Male
chemical_list: D003345:Corticosterone
keywords: carotenoid-based coloration; condition dependence; glucocorticoids; lizard coloration; melanin-based ornaments; multiple signalling; sexual selection; stress response