My PhD project focuses on the study of the melanocortin system, a critical endocrine system in vertebrates. The melanocortin system is a key component of vertebrate hormonal pathways that is associated in humans with single nucleotide polymorphisms (SNPs), and phenotypes such as diseases, mental disorders (REF) and addiction. My thesis is divided into two main lines of research comprising two complementary time scales; namely long term evolution in the vertebrate lineage and evolutionary ecology within a non-model species, the barn owl. First a bioinformatics approach is used to investigate the evolution of the melanocortin genes through the vertebrate phylogeny and identify codon sites important during vertebrate’s evolution. Then, using a molecular approach, I am determining polymorphisms occurring in the Swiss and European barn owl’s MCRs.