Misleading mollies: The effect of an audience on the expression of mating preferences

An increasing body of literature considers the question of how mate choice is influenced by the social environment of the choosing individual (non-independent mate choice). For example, individuals may copy the mate choice of others. A very simple form of socially influenced mate choice, however, remained comparatively little investigated: choosing individuals may adjust their mate choice to the mere presence of rivals. Recent studies in our groups1-4 have examined this question. Using live bearing fish (mollies, Poecilia spp.) as a model, we could show that (a) males will copy the mate choice of other males,5 (b) males cease expressing mating preferences in the presence of a conspecific rival male,1,2 whereas (c) females copy each other's mate choice, but are otherwise not affected by an audience.3 (d) Most importantly, males, when presented with an audience (potential rival), first approached the previously non-preferred female, suggesting that males attempt to lead the rival away from their preferred mate, thereby exploiting male mate choice copying behavior.4 We discuss that these effects are best explained as male adaptations to reduce the risk of sperm competition in a highly dynamic mating system with frequent multiple mating.