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

Mate choice copying, the use of social information from others' mating decisions, is a taxonomically widespread form of social learning that can shape sexual selection. Two meta-analyses concluded that social information has a moderate positive effect on mate choice, but both rest on literature searches now at least seven years old. We asked whether the overall average effect they reported remains supported. Using a multilingual, grey-literature-inclusive search across seven languages, we added 69 effect sizes from 29 studies and harmonised the two source metrics, 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 (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, located within studies and among species rather than across the phylogeny. Small-study effects were strong on both scales, and correcting for them drew the mean towards zero. In some species, individuals do copy conspecifics' mate choices, but the effect is smaller, more variable, and more sensitive to publication bias than previously estimated.