Does diet drive the evolution of head shape and bite force in chameleons of the genus Bradypodion?

The head is a complex integrated system that is implicated in many vital functions. As such, its morphology is impacted by different and sometimes conflicting demands. Consequently, head shape varies greatly depending on the environment and dietary ecology of an organism. Moreover, given its role in territory defence and mating in lizards, it is also subjected to strong sexual selection in these animals.
We investigated the relationships between head shape, bite performance and diet in 14 of the 17 extant Bradypodion species to determine whether variation in diet can explain the observed diversity in bite force and head shape in this genus. We also evaluate differences between sexes in terms of the relationships between head shape, bite force and diet and predict tighter relationships in females given that the head in this sex is principally under natural selection.
Our results show that there is indeed a correlation between head shape, diet and bite force, but the direction and magni...