title: Pheomelanin-based coloration and the ability to cope with variation in food supply and parasitism.
abstract: Although gene by environment interactions may play a key role in the maintenance of genetic polymorphisms, little is known about the ecological factors involved in these interactions. We investigated whether food supply and parasites can mediate covariation between the degree of adult pheomelanin-based coloration, a heritable trait, and offspring body mass in the tawny owl (Strix aluco). We swapped clutches between nests to allocate genotypes randomly among environments. Three weeks after hatching, we challenged the immune system of 80 unrelated nestlings with either a phytohemagglutinin (PHA) or a lipopolysaccharide, surrogates of alternative parasites, and then fed them ad lib. or food-restricted them during the following 6 days in the laboratory. Whatever the immune challenge, nestlings fed ad lib. converted food more efficiently into body mass when their biological mother was dark pheomelanic. In contrast, food-restricted nestlings challenged with PHA lost less body mass when their biological mother was pale pheomelanic. Nestling tawny owls born from differently melanic mothers thus show differing reaction norms relative to food availability and parasitism. This suggests that dark and pale pheomelanic owls reflect alternative adaptations to food availability and parasites, factors known to vary in space and time.
authors.affiliation: Department of Ecology and Evolution, Biophore, University of Lausanne, 1015 Lausanne, Switzerland. romain.piault@unil.ch
authors.forename: Romain
authors.initials: R
authors.lastname: Piault
authors.forename: Julien
authors.initials: J
authors.lastname: Gasparini
authors.forename: Pierre
authors.initials: P
authors.lastname: Bize
authors.forename: Susanne
authors.initials: S
authors.lastname: Jenni-Eiermann
authors.forename: Alexandre
authors.initials: A
authors.lastname: Roulin
mesh_terms: D000220:Adaptation, Biological; D000818:Animals; D001835:Body Weight; D004777:Environment; D005260:Female; D005502:Food; D008070:Lipopolysaccharides; D008297:Male; D008543:Melanins / Q000502:physiology*; D010835:Phytohemagglutinins; D010858:Pigmentation; D020305:Strigiformes / Q000469:parasitology / Q000502:physiology*
chemical_list: D008070:Lipopolysaccharides; D008543:Melanins; D010835:Phytohemagglutinins; C018362:pheomelanin