School of Earth Sciences, University of Bristol, Bristol, BS8 1RL, United Kingdom.
Unidad de Paleontología, Departamento de Biología, Universidad Autónoma de Madrid, Madrid, 28049, Spain.
Evolution. 2019 Mar;73(3):422-435. doi: 10.1111/evo.13655. Epub 2018 Dec 21.
Extensive research on avian adaptive radiations has led to a presumption that beak morphology predicts feeding ecology in birds. However, this ecomorphological relationship has only been quantified in a handful of avian lineages, where associations are of variable strength, and never at a broad macroevolutionary scale. Here, we used shape analysis and phylogenetic comparative methods to quantify the relationships among beak shape, mechanical advantage, and two measures of feeding ecology (feeding behavior and semiquantitative dietary preferences) in a broad sample of modern birds, comprising most living orders. We found a complex relationship, with most variables showing a significant relationship with feeding ecology but little explanatory power. For example, diet accounts for less than 12% of beak shape variation. Similar beak shapes are associated with disparate dietary regimes, even when accounting for diet-feeding behavior relationships and phylogeny. Very few lineages optimize for stronger bite forces, with most birds exhibiting relatively fast, weak bites, even in large predatory taxa. The extreme morphological and behavioral flexibility of the beak in birds suggests that, far from being an exemplary feeding adaptation, avian beak diversification may have been largely contingent on trade-offs and constraints.
对鸟类适应性辐射的广泛研究使人们推测，鸟嘴形态可以预测鸟类的食性生态。然而，这种生态形态关系仅在少数鸟类谱系中进行了量化，这些关联的强度各不相同，而且从未在广泛的宏观进化尺度上进行过量化。在这里，我们使用形态分析和系统发育比较方法来量化现代鸟类（包括大多数现存目）中喙形状、机械优势与两种食性生态测量（觅食行为和半定量饮食偏好）之间的关系。我们发现了一种复杂的关系，大多数变量与食性生态有显著关系，但解释力很小。例如，饮食仅占喙形状变化的不到 12%。相似的喙形状与不同的饮食制度有关，即使考虑到饮食与觅食行为的关系和系统发育。很少有谱系具有较强的咬合力，大多数鸟类的咬合力相对较弱且迅速，即使是在大型捕食性分类群中也是如此。鸟嘴在形态和行为上的极端灵活性表明，鸟类的喙多样化远非典型的觅食适应，可能在很大程度上取决于权衡和限制。
