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DOES DIVING LIMIT BRAIN SIZE IN CETACEANS?

Authors

  • Lori Marino,

    1. Neuroscience and Behavioral Biology Program and Department of Psychology, Emory University, Atlanta, Georgia 30322, U.S.A. E-mail: lmarino@emory.edu and Living Links Center for the Advanced Study of Ape and Human Evolution, Yerkes Regional Primate Center, Atlanta, Georgia 30329, U.S.A.
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  • Daniel Sol,

    1. Department of Biology, McGill University, 1205 Avenue Docteur Penfield, Montréal, Québec H3A 1B1, Canada and Centre de Recerca Ecològica i Aplicacions Forestals (CREAF), Universitat Autònoma de Barcelona E-08193 Bellaterra, Catalonia, Spain
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  • Kristen Toren,

    1. School of Medicine, Emory University, Atlanta, Georgia 30322, U.S.A.
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  • Louis Lefebvre

    1. Department of Biology, McGill University, 1205 avenue Docteur Penfield, Montréal, Québec H3A 1B1, Canada
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Abstract

We test the longstanding hypothesis, known as the dive constraint hypothesis, that the oxygenation demands of diving pose a constraint on aquatic mammal brain size.Using a sample of 23 cetacean species we examine the relationship among six different measures of relative brain size, body size, and maximum diving duration. Unlike previous tests we include body size as a covariate and perform independent contrast analyses to control for phylogeny. We show that diving does not limit brain size in cetaceans and therefore provide no support for the dive constraint hypothesis. Instead, body size is the main predictor of maximum diving duration in cetaceans. Furthermore, our findings show that it is important to conduct robust tests of evolutionary hypotheses by employing a variety of measures of the dependent variable, in this case, relative brain size.

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