Evolutionary divergence in brain size between migratory and resident birds
Date
2010
Authors
Sol, Daniel
Garcia, Nuria
Iwaniuk, Andrew N.
Davis, Katie
Meade, Andrew
Boyle, W. Alice
Szekely, Tamas
Journal Title
Journal ISSN
Volume Title
Publisher
Public Library of Science
Abstract
Despite important recent progress in our understanding of brain evolution, controversy remains regarding the evolutionary
forces that have driven its enormous diversification in size. Here, we report that in passerine birds, migratory species tend to
have brains that are substantially smaller (relative to body size) than those of resident species, confirming and generalizing
previous studies. Phylogenetic reconstructions based on Bayesian Markov chain methods suggest an evolutionary scenario
in which some large brained tropical passerines that invaded more seasonal regions evolved migratory behavior and
migration itself selected for smaller brain size. Selection for smaller brains in migratory birds may arise from the energetic
and developmental costs associated with a highly mobile life cycle, a possibility that is supported by a path analysis.
Nevertheless, an important fraction (over 68%) of the correlation between brain mass and migratory distance comes from a
direct effect of migration on brain size, perhaps reflecting costs associated with cognitive functions that have become less
necessary in migratory species. Overall, our results highlight the importance of retrospective analyses in identifying selective
pressures that have shaped brain evolution, and indicate that when it comes to the brain, larger is not always better.
Description
Sherpa Romeo green journal: open access
Keywords
Brain evolution , Brain size , Migratory birds , Resident birds , Migration
Citation
Sol, D., Garcia, N., Iwaniuk, A., Davis, K., Meade, A., Boyle, W. A., & Szekely, T. (2010). Evolutionary divergence in brain size between migratory and resident birds. PLoS ONE, 5(3), e9617. doi:10.1371/journal.pone.0009617