Canaries changing colors Many animals are sexually dimorphic, with different phenotypes in males and females. To identify the genetic basis of sexual differences in bird coloration, Gazda et al. investigated red coloration in mosaic canaries and related species (see the Perspective by Chen). Using a combination of genetic crosses, genomic mapping, transcriptomics, and comparative analyses, the authors show that trans-regulation of the carotenoid-processing gene BCO2 is involved in sexual dichromatism. Although such variation in coloration among the sexes is common, particularly in birds, there are few candidate genes known to be involved. This study helps to elucidate the molecular mechanisms that underlie the evolution of dichromatism and may aid in uncovering sexually selected traits. Science, this issue p. 1270; see also p. 1185 Differences in color between male and female canaries and finches map to simple molecular mechanisms driven by genes with large effects. Sexual dichromatism, a difference in coloration between males and females, may be due to sexual selection for ornamentation and mate choice. Here, we show that carotenoid-based dichromatism in mosaic canaries, a hybrid phenotype that arises in offspring of the sexually dichromatic red siskin and monochromatic canaries, is controlled by the gene that encodes the carotenoid-cleaving enzyme β-carotene oxygenase 2 (BCO2). Dichromatism in mosaic canaries is explained by differential carotenoid degradation in the integument, rather than sex-specific variation in physiological functions such as pigment uptake or transport. Transcriptome analyses suggest that carotenoid degradation in the integument might be a common mechanism contributing to sexual dichromatism across finches. These results suggest that differences in ornamental coloration between sexes can evolve through simple molecular mechanisms controlled by genes of major effect.

中文翻译：

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鸟类性二色性的遗传机制

金丝雀变色 许多动物是性别二态的，雄性和雌性具有不同的表型。为了确定鸟类颜色性别差异的遗传基础，Gazda 等人。研究了马赛克金丝雀和相关物种的红色（见陈的观点）。作者结合遗传杂交、基因组作图、转录组学和比较分析，表明类胡萝卜素加工基因 BCO2 的反式调节与性二色性有关。尽管这种两性之间的颜色差异很常见，特别是在鸟类中，但已知涉及的候选基因很少。这项研究有助于阐明二色性进化背后的分子机制，并可能有助于揭示性选择特征。科学，这个问题 p。1270; 另见第 1185 雄性和雌性金丝雀和雀类之间的颜色差异映射到由具有巨大影响的基因驱动的简单分子机制。性二色性，雄性和雌性之间的颜色差异，可能是由于装饰和配偶选择的性选择。在这里，我们展示了马赛克金丝雀中基于类胡萝卜素的二色性，这是一种在性二色性红色 siskin 和单色金丝雀的后代中出现的混合表型，由编码类胡萝卜素裂解酶 β-胡萝卜素加氧酶 2 (BCO2) 的基因控制. 马赛克金丝雀的二色性是由外皮中类胡萝卜素降解的差异来解释的，而不是生理功能（如色素吸收或运输）的性别特异性变化。转录组分析表明，外皮中的类胡萝卜素降解可能是导致雀类性别二色性的常见机制。这些结果表明，两性之间观赏色彩的差异可以通过受主要影响基因控制的简单分子机制进化。