Abstracts (first author)
Expression levels of genes belonging to the melanocortin system are associated with melanin-based coloration in two colour polymorphic owl species
The adaptive function of colour polymorphism is a long-standing debate, principally because of limited knowledge of the genetic mechanism underlying morph production. A recent genetic model suggested that the melanocortin system could account for covariations between melanin-based colour morphs, behaviour, morphology and physiology. This genetic system may therefore account for the observed morph-specific life history strategies. In two owl species we explored whether the expression levels of genes belonging to the melanocortin system (MC1R, POMC, PC1, PC2 and the antagonist ASIP) as well as 15 other melanogenic genes are associated with melanin-based coloration. We considered the tawny owl (Strix aluco) because individuals vary continuously from light to dark reddish. We measured gene expression in feather follicles collected in nestlings at the time of melanin production. Our results are consistent with a key role of the melanocortin system on the expression of colour morphs. We indeed found that the expression levels of convertases (that process melanocortin hormones) covary with melanin-based coloration, an effect that strongly depends on genetic polymorphism at the melanocortin-1-receptor (MC1R). We conclude that the melanocortin system may explain why dark and light melanic morphs adopt alternative life history strategies and differentially cope with stressful factors.