10.6084/m9.figshare.4750735.v2 Peter D. Dijkstra Peter D. Dijkstra Sean M. Maguire Sean M. Maguire Rayna M. Harris Rayna M. Harris Agosto A. Rodriguez Agosto A. Rodriguez Ross S. DeAngelis Ross S. DeAngelis Stephanie A. Flores Stephanie A. Flores Hans A. Hofmann Hans A. Hofmann Supplemental Material and Method from The melanocortin system regulates body pigmentation and social behaviour in a colour polymorphic cichlid fish<sup>†</sup> The Royal Society 2017 male–male competition melanocortin receptors stress hormones fish pigmentation 2017-03-24 03:27:57 Journal contribution https://rs.figshare.com/articles/journal_contribution/Supplemental_Material_and_Method_from_The_melanocortin_system_regulates_body_pigmentation_and_social_behaviour_in_a_colour_polymorphic_cichlid_fish_sup_sup_/4750735 The melanocortin system is a neuroendocrine system that regulates a range of physiological and behavioural processes. We examined the extent to which the melanocortin system simultaneously regulates colour and behaviour in the cichlid fish <i>Astatotilapia burtoni</i>. We found that yellow males are more aggressive than blue males, in line with previous studies. We then found that exogenous α-melanocyte-stimulating hormone (α-MSH) increases yellowness of the body and dispersal of xanthophore pigments in both morphs. However, α-MSH had a morph-specific effect on aggression, with only blue males showing an increase in the rate of aggression. Exogenous agouti signalling peptide (ASIP), a melanocortin antagonist, did not affect coloration but reduced the rate of aggression in both colour morphs. Blue males had higher cortisol levels than yellow males. Neural gene expression of melanocortin receptors (<i>mcr</i>) and ligands was not differentially regulated between colour morphs. In the skin, however, <i>mc1r</i> and pro-opiomelanocortin (<i>pomc</i>) <i>β</i> were upregulated in blue males, while <i>asip 1</i> was upregulated in yellow males. The effects of α-MSH on behaviour and body coloration, combined with morph-specific regulation of the stress response and the melanocortin system, suggest that the melanocortin system contributes to the polymorphism in behaviour and coloration in <i>A. burtoni</i>.