It has long been of interest to identify the phenotypic traits that mediate reproductive isolation between related species, and more recently, the genes that underpin them. Much work has focused on identifying genes associated with animal colour, with the candidate gene CYP2J19 identified in laboratory studies as the ketolase converting yellow dietary carotenoids to red ketocarotenoids in birds with red pigments. However, evidence that CYP2J19 explains variation between red and yellow feather coloration in wild populations of birds is lacking. Hybrid zones provide the opportunity to identify genes associated with specific traits. Here we investigate genomic regions associated with colour in red‐fronted and yellow‐fronted tinkerbirds across a hybrid zone in southern Africa. We sampled 85 individuals, measuring spectral reflectance of forecrown feathers and scoring colours from photographs, while testing for carotenoid presence with Raman spectroscopy. We performed a genome‐wide association study to identify associations with carotenoid‐based coloration, using double‐digest RAD sequencing aligned to a short‐read whole genome of a Pogoniulus tinkerbird. Admixture mapping using 104,933 single nucleotide polymorphisms (SNPs) identified a region of chromosome 8 that includes CYP2J19 as the only locus with more than two SNPs significantly associated with both crown hue and crown score, while Raman spectra provided evidence of ketocarotenoids in red feathers. Asymmetric backcrossing in the hybrid zone suggests that yellow‐fronted females mate more often with red‐fronted males than vice versa. Female red‐fronted tinkerbirds mating assortatively with red‐crowned males is consistent with the hypothesis that converted carotenoids are an honest signal of quality.

中文翻译：

---

CYP2J19介导跨天然鸟类杂种区的类胡萝卜素颜色渗入

长期以来，人们一直在寻找介导相关物种之间的生殖隔离的表型性状，最近，还发现了构成它们基础的基因。许多工作都集中在鉴定与动物肤色相关的基因上，在实验室研究中将候选基因CYP2J19鉴定为将红色饮食中的黄色类胡萝卜素转化为红色类胡萝卜素的酮醇酶。但是，有证据表明CYP2J19解释了野生鸟类缺乏红色和黄色羽毛着色之间的差异。杂交区提供了鉴定与特定性状相关的基因的机会。在这里，我们调查了南部非洲一个杂种区中与红额和黄额叮当鸟颜色相关的基因组区域。我们采样了85个人，测量了前额羽毛的光谱反射率和照片中的颜色评分，同时使用拉曼光谱法测试了类胡萝卜素的存在。我们进行了全基因组关联研究，以使用双消化的RAD测序技术与金眼猴的短读完整基因组进行比对，以识别与类胡萝卜素着色有关的关联。小叮当。使用104,933个单核苷酸多态性（SNP）进行的混合作图确定了8号染色体区域，其中唯一的位点为CYP2J19，其中两个以上的SNP与树冠色调和树冠得分均显着相关，而拉曼光谱提供了红色羽毛中类酮类化合物的证据。杂种区的不对称回交表明，黄色正面的雌性与红色正面的雄性交配的频率更高，反之亦然。雌性红额幼鸟与雄性红冠幼鸟分别交配，与这样的假说相符：转化的类胡萝卜素是质量的真实信号。