The feeding apparatus of salamanders consists mainly of the cranium, mandible, teeth, hyobranchial apparatus and the muscles of the cranial region. The morphology of the feeding apparatus in turn determines the boundary conditions for possible food processing (i.e., intraoral mechanical reduction) mechanisms. However, the morphology of the feeding apparatus changes substantially during metamorphosis, prompting the hypothesis that larvae might use a different food processing mechanism than post-metamorphic adults. Salamandrid newts with facultative metamorphosis are suitable for testing this hypothesis as adults with divergent feeding apparatus morphologies often coexist in the same population, share similar body sizes, and feed on overlapping prey spectra. We use high-speed videography to quantify the in vivo movements of key anatomical elements during food processing in paedomorphic and metamorphic Alpine newts (Ichthyosaura alpestris). Additionally, we use micro-computed tomography (μCT) to analyze morphological differences in the feeding apparatus of paedomorphic and metamorphic Alpine newts and sort them into late-larval, mid-metamorphic and post-metamorphic morphotypes. Late-larval, mid-metamorphic and post-metamorphic individuals exhibited clear morphological differences in their feeding apparatus. Regardless of the paedomorphic state being externally evident, paedomorphic specimens can conceal different morphotypes (i.e., late-larval and mid-metamorphic morphotypes). Though feeding on the same prey under the same (aquatic) condition, food processing kinematics differed between late-larval, mid-metamorphic and post-metamorphic morphotypes. The food processing mechanism in the Alpine newt changes along with morphology of the feeding apparatus during ontogeny, from a mandible-based to a tongue-based processing mechanism as the changing morphology of the mandible prevents chewing and the tongue allows enhanced protraction. These results could indicate that early tetrapods, in analogy to salamanders, may have developed new feeding mechanisms in their aquatic environment and that these functional innovations may have later paved the way for terrestrial feeding mechanisms.

中文翻译：

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颅形态的个体发育可塑性与高山new食物加工行为的变化有关

sal的饲养设备主要由颅骨，下颌骨，牙齿，支气管设备和颅骨区域的肌肉组成。进料设备的形态进而确定了可能的食品加工（即口内机械还原）机制的边界条件。然而，喂养设备的形态在变态过程中会发生很大变化，这提示了幼虫可能使用与后变态成虫不同的食物加工机制的假设。具有兼性变态的萨拉曼德里德new适合于检验这一假说，因为成年人的饲喂设备形态各异，通常在同一人群中共存，体型相似，并以重叠的猎物光谱为食。我们使用高速摄影术来量化古生和变质高山new（Ichthyosaura alpestris）在食品加工过程中关键解剖元素的体内运动。此外，我们使用微计算机断层扫描（μCT）分析古生和变质高山new的饲养设备中的形态差异，并将它们分类为后期幼虫，中变质和后变质形态。后期幼虫，中变态和后变态个体在其饲喂设备中表现出明显的形态学差异。不论外部是否有古文字状态，古文字标本都可以隐藏不同的形态类型（即后期幼虫和中变形形态）。尽管在相同的（水生）条件下以相同的猎物为食，但后期幼虫的食物加工运动学有所不同，中变态和后变态形态型。高山new中的食物加工机制会随着个体发育而随着饲喂设备的形态发生变化，从下颌骨转变为基于舌头的加工机制，因为下颌骨的形态变化可防止咀嚼，而舌头则可增强伸直性。这些结果可能表明，与sal一样，早期的四足动物在其水生环境中可能已经开发出新的觅食机制，而这些功能创新后来可能为陆生觅食机制铺平了道路。从下颌骨转变为基于舌头的加工机制，因为下颌骨形态的变化可防止咀嚼，而舌头则可增强伸出力。这些结果可能表明，与sal一样，早期的四足动物在其水生环境中可能已经开发出新的觅食机制，而这些功能创新后来可能为陆生觅食机制铺平了道路。从下颌骨转变为基于舌头的加工机制，因为下颌骨形态的变化可防止咀嚼，而舌头则可增强伸出力。这些结果可能表明，与sal一样，早期的四足动物在其水生环境中可能已经开发出新的觅食机制，而这些功能创新后来可能为陆生觅食机制铺平了道路。