New Insights into Bite Performance: Morphological Trade-Offs Underlying the Duration and Magnitude of Bite Force.

Biting performance is important for feeding, territory defense, and mating in many animals. While maximal bite force is a well-studied trait, other aspects of biting and their variation depending on behavior are rarely considered. Here, we took an innovative approach, where (1) we quantified a novel trait, bite duration in lizards; (2) we examined variation across setups that simulate feeding and antagonistic behavior; and (3) we used F-matrix statistics to investigate how different functional components are optimized for ecological and social demands with respect to individual morphology. Our results did not show differences between the sexes in bite duration, but bite performance varied across experimental setups in males, suggesting a higher functional flexibility in this sex. The investigation of form-function associations revealed that trade-offs, facilitations, and one-to-one relationships are simultaneously involved in the morphological optimization of bite force and duration. Put together, our integrated analysis of two different components of bite performance-force and duration-demonstrates their importance for males in both ecological and social tasks. Our findings also suggest the existence of trade-offs in the morphological optimization of functional components, possibly due to physiological constraints on muscle composition, insertion, and orientation.