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Comparative analysis of encephalization in mammals reveals relaxed constraints on anthropoid primate and cetacean brain scaling
Author(s) -
BODDY A. M.,
McGOWEN M. R.,
SHERWOOD C. C.,
GROSSMAN L. I.,
GOODMAN M.,
WILDMAN D. E.
Publication year - 2012
Publication title -
journal of evolutionary biology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.289
H-Index - 128
eISSN - 1420-9101
pISSN - 1010-061X
DOI - 10.1111/j.1420-9101.2012.02491.x
Subject(s) - encephalization , biology , brain size , allometry , primate , phylogenetic tree , evolutionary biology , phylogenetic comparative methods , evolution of mammals , phylogenetics , zoology , extant taxon , ecology , medicine , biochemistry , gene , magnetic resonance imaging , radiology
There is a well‐established allometric relationship between brain and body mass in mammals. Deviation of relatively increased brain size from this pattern appears to coincide with enhanced cognitive abilities. To examine whether there is a phylogenetic structure to such episodes of changes in encephalization across mammals, we used phylogenetic techniques to analyse brain mass, body mass and encephalization quotient (EQ) among 630 extant mammalian species. Among all mammals, anthropoid primates and odontocete cetaceans have significantly greater variance in EQ, suggesting that evolutionary constraints that result in a strict correlation between brain and body mass have independently become relaxed. Moreover, ancestral state reconstructions of absolute brain mass, body mass and EQ revealed patterns of increase and decrease in EQ within anthropoid primates and cetaceans. We propose both neutral drift and selective factors may have played a role in the evolution of brain–body allometry.