Meeting Abstract
Evolutionary biomechanics offers an opportunity to explore the evolution of disparate biological systems that share common underlying mechanics. Sunfish and mantis shrimp are united by having prey-capture mechanisms actuated by four-bar linkages. Sunfishes capture prey via their oral jaws that are mobilized in part by a linkage connecting the mandible and the operculum. Mantis shrimp subdue prey using a power-amplified raptorial appendage driven by a four-bar linkage. Previous work on the mantis shrimp linkage revealed an evolutionary pattern of “mechanical sensitivity” where the functional output of the linkage (kinematic transmission) was tightly correlated with evolutionary changes in some morphological components but not others. This differential sensitivity of mechanical outputs to changes in specific morphological components is potentially a common feature of linkage systems across biology. To explore this possibility, we compared evolutionary patterns in the four-bar systems of sunfishes and mantis shrimp to see if they would show similar evolutionary patterns. We built dynamic linkage models of both linkage systems and used phylogenetic generalized least squares regression (PGLS) to compare evolutionary shifts in linkage morphology and mechanical outputs derived from the models. We found that in both four-bar systems the kinematics are most sensitive to changes in the output link, while measures of overall displacement are sensitive to changes in the coupler link. Our study illustrates the power of comparative biomechanics, allowing us to compare the evolution of biological systems from different phyla based on common mechanical underpinnings.
