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Samuk, Kieran; Iritani, Davis; Schluter, Dolph

<b>Abstract</b><br/>Uncovering factors that shape variation in brain morphology remains a major challenge in evolutionary biology. Recently, it has been shown that brain size is positively associated with level of parental care behavior in various taxa. One explanation for this pattern is that the cognitive demands of performing complex parental care may require increased brain size. This idea is known as the parental brain hypothesis (PBH). We set out to test the predictions of this hypothesis in wild populations of threespine stickleback (Gasterosteus aculeatus). These fish are commonly known to exhibit (1) uniparental male care and (2) sexual dimorphism in brain size (males>females). To test the PBH, we took advantage of the existence of closely related populations of stickleback that display variation in parental care behavior: common marine threespine sticklebacks (uniparental male care) and white threespine sticklebacks (no care). To begin, we quantified genetic differentiation among two common populations and three white populations from Nova Scotia. We found overall low differentiation among populations, although FST was increased in between-type comparisons. We then measured the brain weights of males and females from all five populations along with two additional common populations from British Columbia. We found that sexual dimorphism in brain size is reversed in white stickleback populations: males have smaller brains than females. Thus, while several alternatives need to be ruled out, the PBH appears to be a reasonable explanation for sexual dimorphism in brain size in threespine sticklebacks.; <b>Usage notes</b><br /><div class="o-metadata__file-usage-entry"><h4 class="o-heading__level3-file-title">Brain weights and SLs of Nova Scotian sticklebacks</h4><div class="o-metadata__file-name">Dryad Brain Data - July 2014.csv</br></div><div class="o-metadata__file-name"></div></div><div class="o-metadata__file-usage-entry"><h4 class="o-heading__level3-file-title">SNP Table for Nova Scotian Sticklebacks</h4><div class="o-metadata__file-description">A table of single nucleotide polymorphisms derived from a sample of males from six populations of Nova Scotian sticklebacks. Each row represents a position in the stickleback reference genome, and each column the genotype of an individual fish. See manuscript for population codes.</div><div class="o-metadata__file-name">WhiteCommon SNP Table - July 2014.txt</br></div></div>

Nova Scotia

Dryad version number: 1</p>

Version status: submitted</p>

Dryad curation status: Published</p>

Sharing link: https://datadryad.org/stash/share/QcQZLtPQZy2DckOQeGAe4ObkhBLIZ-EIxKNnLOkjoi0</p>

Storage size: 4848419</p>

Visibility: public</p>

University of British Columbia Library

10.14288/1.0397990

https://doi.org/10.5683/SP2/WPUGHV; https://doi.org/10.5061/dryad.r8547

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