The role of bite force in the evolution of head shape and head shape dimorphism in Anolis lizards

Abstract

Abstract Patterns of convergent evolution in head shape, combined with performance measures, provide ideal opportunities to understand the processes driving its evolution. Anole lizards represent an excellent subject to test this, as recurrent habitat specialists or ecomorphs evolved independently across different islands. We show that phenotypic similarity corresponds to both phylogenetic similarity and similarity in habitat, indicating that there is convergent evolution in head shape among ecomorphs. Moreover, we show that the evolution of tall, wide heads correlate with the evolution of higher bite forces, driving head shape variation among and within ecomorphs. In addition, the processes affecting head shape variation can differ between sexes, leading to sexual head shape dimorphism. These processes might, however, still depend on the habitat. Consequently, there could also be convergent evolution in head shape dimorphism among ecomorphs. We found no evidence for convergent evolution in sexual head shape dimorphism. Moreover, the sexual head shape dimorphism correlates poorly with bite force, suggesting that intersexual head shape differences are related to other functions. Different processes are thus driving the evolution of head shape and head shape dimorphism. A free Plain Language Summary can be found within the Supporting Information of this article.