Volume 73, Issue 10
ORIGINAL ARTICLE

Larger brains spur species diversification in birds

Ferran Sayol

E-mail address: ferran.sayol@bioenv.gu.se

Department of Biological and Environmental Sciences, University of Gothenburg, SE 405 30 Gothenburg, Sweden

Gothenburg Global Biodiversity Centre, SE 405 30 Gothenburg, Sweden

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Oriol Lapiedra

CREAF, Cerdanyola del Vallès, 08193 Catalonia, Spain

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Simon Ducatez

CREAF, Cerdanyola del Vallès, 08193 Catalonia, Spain

Department of Biology, McGill University, H3A 2T5 Montréal, Canada

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Daniel Sol

CREAF, Cerdanyola del Vallès, 08193 Catalonia, Spain

CSIC, Cerdanyola del Vallès, 08193 Catalonia, Spain

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First published: 13 September 2019

Abstract

Evidence is accumulating that species traits can spur their evolutionary diversification by influencing niche shifts, range expansions, and extinction risk. Previous work has shown that larger brains (relative to body size) facilitate niche shifts and range expansions by enhancing behavioral plasticity but whether larger brains also promote evolutionary diversification is currently backed by insufficient evidence. We addressed this gap by combining a brain size dataset for >1900 avian species worldwide with estimates of diversification rates based on two conceptually different phylogenetic‐based approaches. We found consistent evidence that lineages with larger brains (relative to body size) have diversified faster than lineages with relatively smaller brains. The best supported trait‐dependent model suggests that brain size primarily affects diversification rates by increasing speciation rather than decreasing extinction rates. In addition, we found that the effect of relatively brain size on species‐level diversification rate is additive to the effect of other intrinsic and extrinsic factors. Altogether, our results highlight the importance of brain size as an important factor in evolution and reinforce the view that intrinsic features of species have the potential to influence the pace of evolution.

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