BACKGROUND Many living birds exhibit some nocturnal activity, but the genetic basis and evolutionary origins of their nocturnality remain unknown. RESULTS Here, we used a molecular phyloecological approach to analyze the adaptive evolution of 33 phototransduction genes in diverse bird lineages. Our results suggest that functional enhancement of two night-vision genes, namely, GRK1 and SLC24A1, underlies the nocturnal adaption of living birds. Further analyses showed that the diel activity patterns of birds have remained relatively unchanged since their common ancestor, suggesting that the widespread nocturnal activity of many living birds may largely stem from their common ancestor rather than independent evolution. Despite this evolutionary conservation of diel activity patterns in birds, photoresponse recovery genes were found to be frequently subjected to positive selection in diverse bird lineages, suggesting that birds generally have evolved an increased capacity for motion detection. Moreover, we detected positive selection on both dim-light vision genes and bright-light vision genes in the class Aves, suggesting divergent evolution of the vision of birds from that of reptiles and that different bird lineages have evolved certain visual adaptions to their specific light conditions. CONCLUSIONS This study suggests that the widespread nocturnality of extant birds has a deep evolutionary origin tracing back to their common ancestor.

中文翻译：

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源于其共同祖先的活鸟的广泛夜行性。

背景技术许多活禽具有夜间活动，但是其夜间活动的遗传基础和进化起源仍然未知。结果在这里，我们使用了一种分子系统生态学方法来分析33种光转导基因在不同鸟类谱系中的适应性进化。我们的结果表明，两个夜视基因，即GRK1和SLC24A1的功能增强，是活禽夜间适应的基础。进一步的分析表明，自从它们的共同祖先以来，鸟类的diel活性模式一直保持相对不变，这表明许多活禽的广泛夜间活动可能很大程度上源于其共同祖先，而不是独立的进化。尽管鸟类中diel活动模式得到了这种进化保护，发现光响应恢复基因在不同的鸟类谱系中经常经​​历阳性选择，这表明鸟类通常已经进化出增强的运动检测能力。此外，我们在Aves类中发现了对暗光视觉基因和亮光视觉基因的正选择，这表明鸟类的视觉与爬行动物的视觉进化不同，并且不同的鸟类谱系对它们的特定光照已经进化出一定的视觉适应性情况。结论这项研究表明，现存鸟类的夜行性具有很深的进化起源，可追溯到它们的共同祖先。我们在Aves类中检测到了暗光视觉基因和亮光视觉基因的正选择，这表明鸟类的视觉与爬行动物的视觉发展不同，不同的鸟类谱系已经针对其特定的光照条件发展了某些视觉适应性。结论这项研究表明，现存鸟类的夜行性具有很深的进化起源，可追溯到它们的共同祖先。我们在Aves类中检测到了对暗光视觉基因和亮光视觉基因的正选择，这表明鸟类的视觉与爬行动物的视觉发展不同，不同的鸟类谱系已经针对其特定的光照条件发展了某些视觉适应性。结论这项研究表明现存鸟类的夜行性具有很深的进化起源，可追溯到它们的共同祖先。