Data from: Testosterone regulates CYP2J19-linked carotenoid signal expression in male red-backed fairywrens (Malurus melanocephalus)

Carotenoid pigments produce most red, orange, and yellow colours in
vertebrates. This coloration can serve as an honest signal of quality that
mediates social and mating interactions, but our understanding of the
underlying mechanisms that control carotenoid signal production, including
how different physiological pathways interact to shape and maintain these
signals, remains incomplete. We investigated the role of testosterone in
mediating gene expression associated with a red plumage sexual signal in
red-backed fairywrens (Malurus melanocephalus). In this species, males
within a single population can flexibly produce either red/black nuptial
plumage or female-like brown plumage. Combining correlational analyses
with a field-based testosterone implant experiment and qPCR, we show that
testosterone mediates expression of carotenoid-based plumage in part by
regulating expression of CYP2J19, a ketolase gene associated with
ketocarotenoid metabolism and pigmentation in birds. This is the first
time that hormonal regulation of a specific genetic locus has been linked
to carotenoid production in a natural context, revealing how endocrine
mechanisms produce sexual signals that shape reproductive success.