Imperfect morphological convergence: variable changes in cranial structures underlie transitions to durophagy in moray eels

Convergence is central to the study of evolution because it demonstrates the power of natural selection to deterministically shape phenotypic diversity. However, the conditions under which a common morphology repeatedly evolves may be restrictive. Many factors—such as differing genetic and environmental backgrounds and many-to-one mapping of form to function—contribute to variability in responses to selection. Nevertheless, lineages may evolve similar, even if not identical, forms given a shared selective regime, providing opportunities to examine the relative importance of natural selection, constraint and contingency. Here, we show that following 10 transitions to durophagy in moray eels (Muraenidae), cranial morphology repeatedly evolved toward a novel region of morphological space indicative of enhanced feeding performance on hard prey. Disparity among the resulting 15 durophagous species, however, is greater than disparity among ancestors that fed on large evasive prey, contradicti...

趋同演化是演化生物学研究的核心议题之一，因其直观展现了自然选择以确定性方式塑造表型多样性的强大能力。然而，重复演化出同一形态的前提条件往往具有限制性。诸多因素——例如差异化的遗传与环境背景、形态与功能间的多对一映射关系等——都会导致生物对选择压力的响应存在差异。尽管如此，若类群处于共享的选择环境中，仍可演化出相似（即便并非完全一致）的形态，这为探究自然选择、演化约束与演化偶然性的相对重要性提供了研究契机。
本研究显示，海鳗科（Muraenidae）的10个类群先后完成向食硬食物习性（durophagy）的转变后，其颅部形态（cranial morphology）均反复向形态空间的全新区域演化，这一特征表明它们对硬质猎物的捕食效能得到提升。然而，最终形成的15个食硬食物物种类群间的形态差异度（disparity），要高于以大型逃逸性猎物为食的祖先类群，这与……相悖