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Hibernation constrains brain size evolution in mammals
Author(s) -
Heldstab Sandra A.,
Isler Karin,
Schaik Carel P.
Publication year - 2018
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/jeb.13353
Subject(s) - biology , hibernation (computing) , brain size , phylogenetic comparative methods , torpor , ecology , confounding , energy expenditure , constraint (computer aided design) , phylogenetic tree , evolutionary biology , zoology , statistics , endocrinology , medicine , mechanical engineering , state (computer science) , biochemistry , mathematics , algorithm , computer science , gene , magnetic resonance imaging , engineering , thermoregulation , radiology
The expensive brain hypothesis predicts that the lowest stable level of steady energy input acts as a strong constraint on a species’ brain size, and thus, that periodic troughs in net energy intake should select for reduced brain size relative to body mass. Here, we test this prediction for the extreme case of hibernation. Hibernators drastically reduce food intake for up to several months and are therefore expected to have smaller relative brain sizes than nonhibernating species. Using a comparative phylogenetic approach on brain size estimates of 1104 mammalian species, and controlling for possible confounding variables, we indeed found that the presence of hibernation in mammals is correlated with decreased relative brain size. This result adds to recent comparative work across mammals and amphibians supporting the idea that environmental seasonality (where in extremis hibernation is necessary for survival) imposes an energetic challenge and thus acts as an evolutionary constraint on relative brain size.