Tempo and Pattern of Avian Brain Size Evolution

Ksepka, Daniel T. and Balanoff, Amy M. and Smith, N. Adam and Bever, Gabriel S. and Bhullar, Bhart-Anjan S. and Bourdon, Estelle and Braun, Edward L. and Burleigh, J. Gordon and Clarke, Julia A. and Colbert, Matthew W. and Corfield, Jeremy R. and Degrange, Federico J. and De Pietri, Vanesa L. and Early, Catherine M. and Field, Daniel J. and Gignac, Paul M. and Gold, Maria Eugenia Leone and Kimball, Rebecca T. and Kawabe, Soichiro and Lefebvre, Louis and Marugán-Lobón, Jesús and Mongle, Carrie S. and Morhardt, Ashley and Norell, Mark A. and Ridgely, Ryan C. and Rothman, Ryan S. and Scofield, R. Paul and Tambussi, Claudia P. and Torres, Christopher R. and van Tuinen, Marcel and Walsh, Stig A. and Watanabe, Akinobu and Witmer, Lawrence M. and Wright, Alexandra K. and Zanno, Lindsay E. and Jarvis, Erich D. and Smaers, Jeroen B. (2020) Tempo and Pattern of Avian Brain Size Evolution. Current Biology. ISSN 0960-9822 DOI https://doi.org/10.1016/j.cub.2020.03.060

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Official URL: https://doi.org/10.1016/j.cub.2020.03.060


Relative brain sizes in birds can rival those of primates, but large-scale patterns and drivers of avian brain evolution remain elusive. Here, we explore the evolution of the fundamental brain-body scaling relationship across the origin and evolution of birds. Using a comprehensive dataset sampling> 2,000 modern birds, fossil birds, and theropod dinosaurs, we infer patterns of brain-body co-variation in deep time. Our study confirms that no significant increase in relative brain size accompanied the trend toward miniaturization or evolution of flight during the theropod-bird transition. Critically, however, theropods and basal birds show weaker integration between brain size and body size, allowing for rapid changes in the brain-body relationship that set the stage for dramatic shifts in early crown birds. We infer that major shifts occurred rapidly in the aftermath of the Cretaceous-Paleogene mass extinction within Neoaves, in which multiple clades achieved higher relative brain sizes because of a reduction in body size. Parrots and corvids achieved the largest brains observed in birds via markedly different patterns. Parrots primarily reduced their body size, whereas corvids increased body and brain size simultaneously (with rates of brain size evolution outpacing rates of body size evolution). Collectively, these patterns suggest that an early adaptive radiation in brain size laid the foundation for subsequent selection and stabilization.

Item Type: Article
Uncontrolled Keywords: 2020AREP, IA76
Subjects: 04 - Palaeobiology
Divisions: 04 - Palaeobiology
08 - Green Open Access
Journal or Publication Title: Current Biology
Identification Number: https://doi.org/10.1016/j.cub.2020.03.060
Depositing User: Sarah Humbert
Date Deposited: 30 Apr 2020 21:01
Last Modified: 23 Apr 2021 00:00
URI: http://eprints.esc.cam.ac.uk/id/eprint/4697

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