Data from: Trait decoupling promotes evolutionary diversification of the trophic and acoustic system of damselfishes

Trait decoupling, wherein evolutionary release of constraints permits specialization of formerly integrated structures, represents a major conceptual framework for interpreting patterns of organismal diversity. However, few empirical tests of this hypothesis exist. A central prediction, that the tempo of morphological evolution and ecological diversification should increase following decoupling events, remains inadequately tested. In damselfishes (Pomacentridae), a ceratomandibular ligament links the hyoid bar and lower jaws, coupling two main morphofunctional units directly involved in both feeding and sound production. Here, we test the decoupling hypothesis by examining the evolutionary consequences of the loss of the ceratomandibular ligament in multiple damselfish lineages. As predicted, we find that rates of morphological evolution of trophic structures increased following the loss of the ligament. However, this increase in evolutionary rate is not associated with an increase in trophic breadth, but rather with morphofunctional specialization for the capture of zooplanktonic prey. Lineages lacking the ceratomandibular ligament also shows different acoustic signals (i.e. higher variation of pulse periods) from others, resulting in an increase of the acoustic diversity across the family. Our results support the idea that trait decoupling can increase morphological and behavioural diversity through increased specialization rather than the generation of novel ecotypes.性状解耦（Trait decoupling）指进化约束释放使得原先整合的结构得以特化，是阐释生物多样性格局的核心概念框架之一。然而，针对该假说的实证检验却寥寥无几。其核心预测为：解耦事件发生后，形态进化速率与生态分化速度理应提升，但该预测仍未得到充分验证。在雀鲷科（Pomacentridae）鱼类中，角下颌韧带（ceratomandibular ligament）连接舌弓与下颌，将直接参与摄食与发声的两个核心形态功能单元耦合在一起。本研究通过探究多个雀鲷支系中角下颌韧带丢失的进化效应，对性状解耦假说进行检验。正如预测所示，我们发现摄食结构的形态进化速率在该韧带丢失后有所提升。但该进化速率的提升并未伴随摄食生态位宽度的扩大，而是指向针对浮游动物猎物捕获的形态功能特化。缺失角下颌韧带的支系同样表现出与其他支系迥异的声学信号（即脉冲周期变异度更高），进而提升了整个雀鲷科的声学多样性。本研究结果证实，性状解耦可通过强化特化而非产生新型生态型，提升生物的形态与行为多样性。