Evolution of a multifunctional trait: shared effects of foraging ecology and thermoregulation on beak morphology, with consequences for song evolution

While morphological traits are often associated with multiple functions, it remains unclear how evolution balances the selective effects of different functions. Birds' beaks function in foraging, but also in thermoregulating and singing, among other behaviours. Studies of beak evolution abound, however most focus on a single function. Thus, we quantified relative contributions of different functions over an evolutionary time scale. We measured beak shape using geometric morphometrics and compared this trait to foraging behaviour, climatic variables, and song characteristics in a phylogenetic comparative study of an Australasian radiation of songbirds (Meliphagidae). We found that both climate and foraging behaviour were significantly correlated with beak shape and size. However, foraging ecology had a greater effect on shape, and climate had a greater effect on size. We also found that evolutionary changes in beak morphology had significant consequences for vocal performance: species wi...

尽管形态性状通常兼具多种功能，但演化如何平衡不同功能带来的选择效应仍未明晰。鸟类的喙不仅可用于觅食，还能参与体温调节、鸣唱等多种行为活动。现有喙演化相关研究数量众多，但绝大多数仅聚焦于单一功能。有鉴于此，我们在演化时间尺度下量化了不同功能的相对贡献量。我们以澳大拉西亚辐射演化的鸣禽类群——吸蜜鸟科（Meliphagidae）为研究对象开展系统发育比较研究，采用几何形态测量学（geometric morphometrics）方法测定喙形，并将该性状与觅食行为、气候变量及鸣唱特征进行关联分析。研究结果表明，气候条件与觅食行为均与喙的形状和大小存在显著关联。但觅食生态对喙形的影响更为显著，而气候对喙大小的影响更强。此外我们还发现，喙形态的演化变化对发声性能具有显著影响：物种wi...