Data from: Genetic basis for red coloration in birds

The yellow and red feather pigmentation of many bird species [1] plays
pivotal roles in social signaling and mate choice [2, 3]. To produce red
pigments, birds ingest yellow carotenoids and endogenously convert them
into red ketocarotenoids via an oxidation reaction catalyzed by a
previously unknown ketolase [4–6]. We investigated the genetic basis for
red coloration in birds using whole-genome sequencing of red siskins
(Spinus cucullata), common canaries (Serinus canaria), and ‘‘red factor’’
canaries, which are the hybrid product of crossing red siskins with common
canaries [7]. We identified two genomic regions introgressed from red
siskins into red factor canaries that are required for red coloration. One
of these regions contains a gene encoding a cytochrome P450 enzyme,
CYP2J19. Transcriptome analysis demonstrates that CYP2J19 is significantly
upregulated in the skin and liver of red factor canaries, strongly
implicating CYP2J19 as the ketolase that mediates red coloration in birds.
Interestingly, a second introgressed region required for red feathers
resides within the epidermal differentiation complex, a cluster of genes
involved in development of the integument. Lastly, we present evidence
that CYP2J19 is involved in ketocarotenoid formation in the retina. The
discovery of the carotenoid ketolase has important implications for
understanding sensory function and signaling mediated by carotenoid
pigmentation.