Whole genome sequencing identifies candidate genes and mutations that can explain diluted and other colour varieties of domestic canaries ( Serinus canaria )

The domestic canary (Serinus canaria) is one of the most common pet birds and has been extensively selected and bred over the last few centuries to constitute many different varieties. Plumage pigmentation is one of the main phenotypic traits that distinguish canary breeds and lines. Feather colours in these birds, similarly to other avian species, are mainly depended on the presence of two major types of pigments: carotenoids and melanins. In this study, we exploited whole genome sequencing (WGS) datasets produced from five canary lines or populations (Black Frosted Yellow, Opal, Onyx, Opal × Onyx and Mogno, some of which carrying different putative dilute alleles), complemented with other WGS datasets retrieved from previous studies, to identify candidate genes that might explain pigmentation variability across canary breeds and varieties. Sequencing data were obtained using a DNA pool-seq approach and genomic data were compared using window-based FST analyses. We identified signatures of selection in genomic regions harbouring genes involved in carotenoid-derived pigmentation variants (CYP2J19, EDC, BCO2 and SCARB1), confirming the results reported by previous works, and identified several other signatures of selection in the correspondence of melanogenesis-related genes (AGRP, ASIP, DCT, EDNRB, KITLG, MITF, MLPH, SLC45A2, TYRP1 and ZEB2). Two putative causative mutations were identified in the MLPH gene that may explain the Opal and Onyx dilute mutant alleles. Other signatures of selection were also identified that might explain additional phenotypic differences between the investigated canary populations.