Early events in the evolutionary history of a clade can shape the sensory systems of descendant lineages. Although the avian ancestor may not have had a sweet receptor, the widespread incidence of nectar-feeding birds suggests multiple acquisitions of sugar detection. In this study, we identify a single early sensory shift of the umami receptor (the T1R1-T1R3 heterodimer) that conferred sweet-sensing abilities in songbirds, a large evolutionary radiation containing nearly half of all living birds. We demonstrate sugar responses across species with diverse diets, uncover critical sites underlying carbohydrate detection, and identify the molecular basis of sensory convergence between songbirds and nectar-specialist hummingbirds. This early shift shaped the sensory biology of an entire radiation, emphasizing the role of contingency and providing an example of the genetic basis of convergence in avian evolution.

进化枝进化史上的早期事件可以塑造后代谱系的感觉系统。尽管鸟类祖先可能没有甜味受体，但以花蜜为食的鸟类的普遍发病率表明糖检测的多次获得。在这项研究中，我们确定了鲜味受体（T1R1-T1R3 异二聚体）的单一早期感官转变，它赋予鸣禽感知甜味的能力，这是一种包含近一半所有活鸟类的大型进化辐射。我们展示了具有不同饮食的物种之间的糖反应，揭示了碳水化合物检测的关键位点，并确定了鸣禽和花蜜专家蜂鸟之间感觉融合的分子基础。这种早期的转变塑造了整个辐射的感官生物学，