The Multifactorial Nature of Beak and Skull Shape Evolution in Parrots and Cockatoos (Psittaciformes)

Authors

Jen A. Bright, University of South FloridaFollow
Jesús Marugán-Lobón, Unidad de Paleontologıa
Emily J. Rayfield, University of Bristol
Samuel N. Cobb, University of York

Document Type

Article

Publication Date

5-2019

Keywords

Birds, Geometric morphometrics, Allometry, Integration, Feeding, Parrots

Digital Object Identifier (DOI)

https://doi.org/10.1186/s12862-019-1432-1

Abstract

Background: The Psittaciformes (parrots and cockatoos) are characterised by their large beaks, and are renowned for their ability to produce high bite forces. These birds also possess a suite of modifications to their cranial architecture interpreted to be adaptations for feeding on mechanically resistant foods, yet the relationship between cranial morphology and diet has never been explicitly tested. Here, we provide a three-dimensional geometric morphometric analysis of the developmental and biomechanical factors that may be influencing the evolution of psittaciformes’ distinctive cranial morphologies.

Results: Contrary to our own predictions, we find that dietary preferences for more- or less- mechanically resistant foods have very little influence on beak and skull shape, and that diet predicts only 2.4% of the shape variation in psittaciform beaks and skulls. Conversely, evolutionary allometry and integration together predict almost half the observed shape variation, with phylogeny remaining an important factor in shape identity throughout our analyses, particularly in separating cockatoos (Cacatuoidea) from the true parrots (Psittacoidea).

Conclusions: Our results are similar to recent findings about the evolutionary trajectories of skull and beak shape in other avian families. We therefore propose that allometry and integration are important factors causing canalization of the avian head, and while diet clearly has an influence on beak shape between families, this may not be as important at driving evolvability within families as is commonly assumed.

Rights Information

This work is licensed under a Creative Commons Attribution 4.0 License.

Was this content written or created while at USF?

Yes

Citation / Publisher Attribution

BMC Evolutionary Biology, v. 19, art. 104

Scholar Commons Citation

Bright, Jen A.; Marugán-Lobón, Jesús; Rayfield, Emily J.; and Cobb, Samuel N., "The Multifactorial Nature of Beak and Skull Shape Evolution in Parrots and Cockatoos (Psittaciformes)" (2019). School of Geosciences Faculty and Staff Publications. 2160.
https://digitalcommons.usf.edu/geo_facpub/2160