Mate choice copying is a form of social learning that is defined as the increased likelihood of an individual choosing a particular mate after observing another individual choosing that mate. Mate choice copying has been demonstrated in a range of taxonomic groups, but not usually for both sexes. Mate choice copying experiments were performed here using two congeneric sympatric darters, Etheostoma flabellare and E. zonale. In E. flabellare, males guard a nest site under a rock and care for developing eggs. In E. zonale, eggs are attached to filamentous green algae and neither sex provides parental care. Our results provide the first evidence that mate choice copying occurs in darters. Previously it was hypothesised that copying might be more common in species and sexes that provide parental care, the reasoning being that the costs of choosing poorly may be higher. However, mate choice copying was found in both sexes of E. zonale (no parental care) and in male but not female E. flabellare (male only parental care). Thus, the only group that did not mate choice copy was the one whose mate would be providing care, and even E. flabellare females copy the mate choice of other females by some definitions. The relationship, if any, between which sex provides parental care and whether copying occurs remains unclear, and the number of species for which such data are available is limited.
Human mate-choice copying is domain-general social learning