Metamorphosis is widespread across the animal kingdom and induces fundamental changes in the morphology, habitat and resources used by an organism during its lifetime. Metamorphic species are likely to experience more dynamic selective pressures through ontogeny compared with species with single-phase life cycles, which may drive divergent evolutionary dynamics. Here, we reconstruct the cranial evolution of the salamander using geometric morphometric data from 148 species spanning the order’s full phylogenetic, developmental and ecological diversity. We demonstrate that life cycle influences cranial shape diversity and rate of evolution. Shifts in the rate of cranial evolution are consistently associated with transitions from biphasic to either direct-developing or paedomorphic life cycle strategies. Direct-developers exhibit the slowest rates of evolution and the lowest disparity, and paedomorphic species the highest. Species undergoing complete metamorphosis (biphasic and direct-developing) exhibit greater cranial modularity (evolutionary independence among regions) than do paedomorphic species, which undergo differential metamorphosis. Biphasic and direct-developing species also display elevated disparity relative to the evolutionary rate for bones associated with feeding, whereas this is not the case for paedomorphic species. Metamorphosis has profoundly influenced salamander cranial evolution, requiring greater autonomy of cranial elements and facilitating the rapid evolution of regions that are remodelled through ontogeny. Rather than compounding functional constraints on variation, metamorphosis seems to have promoted the morphological evolution of salamanders over 180 million years, which may explain the ubiquity of this complex life cycle strategy across disparate organisms.

变态现象在整个动物界中很普遍，并且会在生物的一生中引起其形态，栖息地和资源的根本变化。与具有单相生命周期的物种相比，变质物种通过个体发育可能会经历更多的动态选择压力，这可能会推动不同的进化动力学。在这里，我们使用来自148个物种的几何形态学数据重建了am的颅骨进化，该物种涵盖了该物种的完整的系统发育，发育和生态多样性。我们证明生命周期影响颅骨形状多样性和进化的速度。颅骨进化速率的变化与从双相生命周期过渡到直接发育或古生命周期策略始终相关。直接开发者的进化速度最慢，差异最小，古样物种最高。经历完全变态（双相和直接发育）的物种比经历变态变质的变态物种表现出更大的颅骨模块化（区域间的进化独立性）。相对于与进食相关的骨骼的进化速度，双相和直接发育的物种也表现出更高的差异，而对于古形物种则不是这样。变态已经深刻地影响了sal的颅骨进化，要求颅骨元素具有更大的自治性，并促进通过个体发育而重塑的区域的快速进化。与其在变体上加重功能约束，