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Dryad

Craniofacial modularity and cranial kinesis evolution in the adaptive radiation of Furnariidae (Aves: Passeriformes)

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Dec 27, 2024 version files 14.64 MB

Abstract

The role of phenotypic modularity in the evolution of skull morphology in birds has been a subject of debate in recent years. Furnariids (ovenbirds, woodcreepers, and allies), a spectacular avian adaptive radiation, are distinguished in their cranial morphology as the only passerines with two types of cranial kinesis, constituting a great model to test whether the evolution of novelties in cranial kinesis was associated with shifts in patterns of evolutionary modularity and allometry in the avian skull. Our analyses by means of geometric morphometric tools and phylogenetic comparative methods show that the beak and neurocranium of furnariids evolved in a modular fashion and were shaped by the cranial kinesis evolution. Besides, species with prokinesis show a higher degree of modularity and morphological disparity, lower phenotypic rates, as well a higher contribution of allometry in the evolution of the beak morphology than species with proximal rhynchokinesis, suggesting, as observed in several vertebrates, that the functional demands associated with higher degrees of cranial kinesis promoted rapid integration throughout the skull. Prokinetic - robust morphotypes and proximal rhynchokinetic - gracile morphotypes, have repeatedly evolved by evolutionary convergence in both evolutionary modules, which suggests the existence of functional trade-offs and long-standing adaptive optima related to cranial kinesis.