Data from: Elaborate visual and acoustic signals evolve independently in a large, phenotypically diverse radiation of songbirds

The concept of a macroevolutionary trade-off among sexual signals has a storied history in evolutionary biology. Theory predicts that if multiple sexual signals are costly for males to produce or maintain and females prefer a single, sexually selected trait, then an inverse correlation between sexual signal elaborations is expected among species. However, empirical evidence for what has been termed the ‘transfer hypothesis’ is mixed, which may reflect different selective pressures among lineages, evolutionary covariates or methodological differences among studies. Here, we examine interspecific correlations between song and plumage elaboration in a phenotypically diverse, widespread radiation of songbirds, the tanagers. The tanagers (Thraupidae) are the largest family of songbirds, representing nearly 10% of all songbirds. We assess variation in song and plumage elaboration across 301 species, representing the largest scale comparative study of multimodal sexual signalling to date. We consider whether evolutionary covariates, including habitat, structural and carotenoid-based coloration, and subfamily groupings influence the relationship between song and plumage elaboration. We find that song and plumage elaboration are uncorrelated when considering all tanagers, although the relationship between song and plumage complexity varies among subfamilies. Taken together, we find that elaborate visual and vocal sexual signals evolve independently among tanagers.

性信号之间的宏观演化权衡（macroevolutionary trade-off）概念在演化生物学中拥有悠久的研究历史。理论预测，若雄性产生或维持多重性信号需付出高昂成本，且雌性仅偏好单一性选择性状，则不同物种间的性信号精细化程度应呈现负相关关系。然而，被称为‘传递假说（transfer hypothesis）’的实证证据却存在分歧，这或许反映了不同支系间的选择压力差异、演化协变量差异，或是不同研究间的方法学差异。本研究针对表型多样、分布广泛的鸣禽辐射类群——裸鼻雀科（Thraupidae），探讨其鸣唱与羽饰精细化程度的种间相关性。裸鼻雀科是现存最大的鸣禽科类群，占所有鸣禽物种的近10%。我们对301个物种的鸣唱与羽饰精细化程度变异展开评估，这是目前为止规模最大的多模态性信号（multimodal sexual signalling）比较研究。我们考量了包括栖息地、身体结构与类胡萝卜素基着色在内的演化协变量，以及亚科类群划分是否会影响鸣唱与羽饰精细化程度间的关联。研究发现，当纳入所有裸鼻雀物种时，鸣唱与羽饰精细化程度并无相关性，但鸣唱复杂度与羽饰复杂度间的关联因亚科不同而存在差异。综合来看，裸鼻雀类群中，复杂的视觉与发声性信号呈现独立演化的模式。