The Evolution of Relative Brain Size in Marsupials Is Energetically Constrained but Not Driven by Behavioral Complexity

Weisbecker, Vera, Blomberg, Simon, Goldizen, Anne W, Brown, Meredeth and Fisher, Diana (2015) The Evolution of Relative Brain Size in Marsupials Is Energetically Constrained but Not Driven by Behavioral Complexity. Brain, Behavior and Evolution, 85 2: 125-135. doi:10.1159/000377666

Author Weisbecker, Vera
Blomberg, Simon
Goldizen, Anne W
Brown, Meredeth
Fisher, Diana
Title The Evolution of Relative Brain Size in Marsupials Is Energetically Constrained but Not Driven by Behavioral Complexity
Journal name Brain, Behavior and Evolution   Check publisher's open access policy
ISSN 0006-8977
Publication date 2015-05-07
Year available 2015
Sub-type Article (original research)
DOI 10.1159/000377666
Open Access Status
Volume 85
Issue 2
Start page 125
End page 135
Total pages 11
Place of publication Basel, Switzerland
Publisher S. Karger AG
Language eng
Subject 2806 Developmental Neuroscience
2802 Behavioral Neuroscience
Abstract Evolutionary increases in mammalian brain size relative to body size are energetically costly but are also thought to confer selective advantages by permitting the evolution of cognitively complex behaviors. However, many suggested associations between brain size and specific behaviors - particularly related to social complexity - are possibly confounded by the reproductive diversity of placental mammals, whose brain size evolution is the most frequently studied. Based on a phylogenetic generalized least squares analysis of a data set on the reproductively homogenous clade of marsupials, we provide the first quantitative comparison of two hypotheses based on energetic constraints (maternal investment and seasonality) with two hypotheses that posit behavioral selection on relative brain size (social complexity and environmental interactions). We show that the two behavioral hypotheses have far less support than the constraint hypotheses. The only unambiguous associates of brain size are the constraint variables of litter size and seasonality. We also found no association between brain size and specific behavioral complexity categories within kangaroos, dasyurids, and possums. The largest-brained marsupials after phylogenetic correction are from low-seasonality New Guinea, supporting the notion that low seasonality represents greater nutrition safety for brain maintenance. Alternatively, low seasonality might improve the maternal support of offspring brain growth. The lack of behavioral brain size associates, found here and elsewhere, supports the general ‘cognitive buffer hypothesis' as the best explanatory framework of mammalian brain size evolution. However, it is possible that brain size alone simply does not provide sufficient resolution on the question of how brain morphology and cognitive capacities coevolve.
Keyword Brain size
Maternal investment
Life history
Q-Index Code C1
Q-Index Status Confirmed Code
Grant ID DE120102034
Institutional Status UQ

Document type: Journal Article
Sub-type: Article (original research)
Collections: Official 2016 Collection
School of Biological Sciences Publications
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Citation counts: TR Web of Science Citation Count  Cited 9 times in Thomson Reuters Web of Science Article | Citations
Scopus Citation Count Cited 11 times in Scopus Article | Citations
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