Modularity and rates of evolutionary change in a power-amplified prey capture system

The dynamic interplay among structure, function and phylogeny form a classic triad of influences on the patterns and processes of biological diversification. While these dynamics are widely recognized as important, quantitative analyses of their interactions have infrequently been applied to biomechanical systems. Here we analyze these factors using a fundamental biomechanical mechanism: power amplification. Power-amplified systems use springs and latches to generate extremely fast and powerful movements. This study focuses specifically on the power amplification mechanism in the fast raptorial appendages of mantis shrimp (Crustacea: Stomatopoda). Using geometric morphometric and phylogenetic comparative analyses, we measured evolutionary modularity and rates of morphological evolution of the raptorial appendage’s biomechanical components. We found that “smashers” (hammer-shaped raptorial appendages) exhibit lower modularity and 10-fold slower rates of morphological change when compared...