Data from: Common evolutionary trends underlie the four-bar linkage systems of sunfish and mantis shrimp

Comparative biomechanics offers an opportunity to explore the evolution of disparate biological systems that share common underlying mechanics. Four-bar linkage modelling has been applied to various biological systems such as fish jaws and crustacean appendages to explore the relationship between biomechanics and evolutionary diversification. Mechanical sensitivity states that the functional output of a mechanical system will show differential sensitivity to changes in specific morphological components. We document similar patterns of mechanical sensitivity in two disparate four-bar systems from different phyla: the opercular four-bar system in centrarchid fishes and the raptorial appendage of stomatopods. We built dynamic linkage models of 20 centrarchid and 36 stomatopod species and used phylogenetic generalized least squares regression (PGLS) to compare evolutionary shifts in linkage morphology and mechanical outputs derived from the models. In both systems, the kinematics of the four-bar mechanism show significant evolutionary correlation with the output link, while travel distance of the output arm is correlated with the coupler link. This common evolutionary pattern seen in both fish and crustacean taxa is a potential consequence of the mechanical principles underlying four-bar systems. Our results illustrate the potential influence of physical principles on morphological evolution across biological systems with different structures, behaviors and ecologies.

比较生物力学为探究共享底层力学机制的迥异生物系统的演化提供了重要契机。四连杆机构建模（Four-bar linkage modelling）已被应用于鱼类颌骨、甲壳类附肢等多种生物系统，以探究生物力学与演化分异之间的关联。机械敏感性原理（Mechanical sensitivity）指出，机械系统的功能输出会对特定形态组分的变化表现出差异化敏感性。我们在两个源自不同门类的迥异四连杆系统中，观测到了相似的机械敏感性模式：日鲈科鱼类的鳃盖四连杆系统，以及口足类动物的捕食附肢。我们构建了20种日鲈科鱼类和36种口足类动物的动态连杆模型，并运用系统发育广义最小二乘回归（phylogenetic generalized least squares regression, PGLS），对比了模型推导得到的连杆形态与力学输出的演化偏移。在这两个系统中，四连杆机构的运动学均与输出连杆呈现出显著的演化相关性，而输出臂的行程距离则与连接杆（coupler link）相关联。这种在鱼类和甲壳类类群中均观测到的共同演化模式，可能源于四连杆系统背后的力学原理。我们的研究结果表明，物理原理可对结构、行为与生态各异的各类生物系统的形态演化产生潜在影响。