Data from: Reversed brain size sexual dimorphism accompanies loss of parental care in white sticklebacks

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.

Usage notes

Brain weights and SLs of Nova Scotian sticklebacks Dryad Brain Data - July 2014.csv SNP Table for Nova Scotian Sticklebacks 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.

WhiteCommon SNP Table - July 2014.txt