Department of Integrative Biology, University of Texas, Austin, Texas, 78712.
Department of Biology, University of Washington, Seattle, Washington, 98105.
Evolution. 2022 Dec;76(12):2959-2974. doi: 10.1111/evo.14578. Epub 2022 Aug 9.
The relationship between skull morphology and diet is a prime example of adaptive evolution. In mammals, the skull consists of the cranium and the mandible. Although the mandible is expected to evolve more directly in response to dietary changes, dietary regimes may have less influence on the cranium because additional sensory and brain-protection functions may impose constraints on its morphological evolution. Here, we tested this hypothesis by comparing the evolutionary patterns of cranium and mandible shape and size across 100+ species of carnivoran mammals with distinct feeding ecologies. Our results show decoupled modes of evolution in cranial and mandibular shape; cranial shape follows clade-based evolutionary shifts, whereas mandibular shape evolution is linked to broad dietary regimes. These results are consistent with previous hypotheses regarding hierarchical morphological evolution in carnivorans and greater evolutionary lability of the mandible with respect to diet. Furthermore, in hypercarnivores, the evolution of both cranial and mandibular size is associated with relative prey size. This demonstrates that dietary diversity can be loosely structured by craniomandibular size within some guilds. Our results suggest that mammal skull morphological evolution is shaped by mechanisms beyond dietary adaptation alone.
颅骨形态与饮食之间的关系是适应进化的一个主要例子。在哺乳动物中，颅骨由颅骨和下颌骨组成。虽然下颌骨预计会更直接地进化以适应饮食变化，但饮食方式对颅骨的影响可能较小，因为额外的感官和大脑保护功能可能会对其形态进化施加限制。在这里，我们通过比较 100 多种具有不同食性生态的食肉哺乳动物的颅骨和下颌骨形状和大小的进化模式来检验这一假设。我们的结果表明，颅骨和下颌骨形状的进化模式是分离的；颅骨形状遵循基于进化枝的进化转变，而下颌骨形状的进化与广泛的饮食模式有关。这些结果与关于食肉动物形态进化的层次结构的先前假说以及下颌骨相对于饮食的更大进化灵活性一致。此外，在超食肉动物中，颅骨和下颌骨大小的进化与相对猎物大小有关。这表明在某些类群中，饮食多样性可以通过颅颌大小来松散地构建。我们的结果表明，哺乳动物颅骨形态的进化是由除饮食适应以外的机制所塑造的。
