Meeting Abstract
Plethodontid salamanders are characterized by specialized feeding mechanisms, with ballistic and thermally robust tongue projection having evolved multiple times. All ballistic taxa project their tongues with an elastic-recoil mechanism that not only amplifies muscle power but also confers relative thermal insensitivity to projection. To understand the morphological foundation of this derived mechanism, we measured the performance of tongue projection and retraction at a range of temperatures and examined the morphology of the tongue apparatus in several ballistic and non-ballistic species from across the plethodontid phylogeny. Using phylogenetic comparative methods we found that taxa with greater projector muscle mass relative to projectile (i.e., tongue) mass produce higher power output and project their tongues with greater thermal robustness. This relationship appears to be largely driven by the evolution of relatively large projector muscles, high power output and high thermal robustness in the clade containing Hydromantes and Ensatina compared to its sister clade containing Plethodon. These results suggest that both thermal robustness and high power output are enabled by the ability to accommodate reduced mass-specific work of the projector muscle afforded by its relatively larger mass.
