Negative frequency-dependent behaviours in Trinidadian guppies ( Poecilia reticulata ): male–male aggression and dispersal

Negative frequency-dependent (NFD) selection, a form of balancing selection where the fitness associated with a given phenotype or genotype is negatively correlated with its relative abundance in the population, is a particularly powerful process that can contribute to the maintenance of genetic variation. Guppies (Poecilia reticulata) have been the focus of a number of studies of negative frequency-dependent selection (NFDS) for several reasons. Male Trinidadian guppies exhibit extreme variation in colour patterns and studies have shown that male guppies with rare morphs have both a survival and reproductive advantage over common morph males in the lab and in natural populations. The goal of this study was to determine whether changes in the mating strategies of common morph males, which are less preferred by female guppies, could contribute to the pattern of NFD survival observed in natural populations. We manipulated male morph frequency in an artificial stream setup and recorded male mating, aggressive and dispersal behaviours in the presence of females. Rare morph males that dispersed were significantly less likely to engage in aggressive interactions with other males in their trials before they moved, potentially providing them with enhanced opportunities to court and mate with females in their home pool. This article is part of the theme issue 'Exploring negative frequency dependent selection across levels: from genetics to ecology and back again'.