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.类胡萝卜素（Carotenoid）色素是脊椎动物体内绝大多数红色、橙色与黄色体色的来源。此类体色可作为反映个体品质的诚实信号，介导社交与交配互动，但目前学界对调控类胡萝卜素信号生成的底层机制——包括不同生理通路如何协同塑造并维持此类信号——的认知仍不完整。本研究以红背细尾鹩莺（Malurus melanocephalus）为研究对象，探究睾酮（testosterone）介导其红色羽毛性信号相关基因表达的作用。该物种的单个种群内，雄性可灵活呈现两种羽型：要么是红黑相间的繁殖婚羽，要么是类似雌性的棕褐色羽衣。本研究结合相关性分析、野外睾酮植入实验与实时荧光定量PCR（qPCR）技术，证实睾酮可通过调控鸟类体内与酮化类胡萝卜素代谢及色素沉着相关的酮化酶基因CYP2J19的表达，部分介导基于类胡萝卜素的羽毛体色生成。这是首次在自然情境下，将特定基因位点的激素调控与类胡萝卜素生成建立关联，揭示了内分泌机制如何通过生成性信号影响繁殖成功率。