Mate choice copying in non-human animals: an update of two meta-analyses

<jats:p>Mate choice copying, the use of social information from the mating decisions of others, is a taxonomically widespread form of social learning with the potential to shape sexual selection. Two meta-analyses concluded that social information moderately and positively biases mate choice, but both rest on literature searches now at least seven years old. Using a multilingual, grey-literature-inclusive search across seven languages, we added 69 effect sizes from 29 studies to the original datasets and harmonized the two source metrics onto common scales, giving 227 Hedges’ g effect sizes from 87 studies and 172 log odds ratios from 69 studies across 33 species. Re-analysed with phylogenetically informed multilevel models, the overall effect remained positive and significant but was appreciably smaller than before (Hedges’ g = 0.45, 95% CI: 0.25 to 0.66, vs. 0.58; odds ratio = 1.81, 95% CI: 1.34 to 2.45, vs. 2.71). Heterogeneity was high and concentrated within studies and among species, not across the phylogeny. We detected strong small-study effects on both scales, and correcting for them drew the adjusted mean towards zero. Overall, in some species, individuals do copy the mate choices of conspecifics, but the effect is smaller, more variable, and more sensitive to publication bias than previously estimated.</jats:p>