Male and female responses to species-specific coloration in darters (Percidae: Etheostoma)

Male secondary sexual traits often comprise multiple components and can function in different contexts. Male signals can target females for mating, males for aggression, and may also function in interspecific interactions. In darter fishes (Percidae: Etheostoma), male nuptial coloration is a multicomponent secondary sexual signal. Females are known to respond to this signal in both intra- and interspecific contexts; they prefer conspecific over heterospecific coloration and prefer a particular colour variant within species. We also have shown that two components of this complex signal (colour and pattern) are each sufficient, in isolation, to attract females. Here, we demonstrate that males also respond to variation in nuptial coloration. Males of two sympatric species showed an association preference for motorized models with conspecific over heterospecific coloration. We also sought to determine whether colour or pattern presides over the other in its influence on female and male behaviour. Using model fish representing conspecific colour (hue) with mismatched heterospecific patterning (and vice versa), we asked whether either sex preferred one element over the other. Female and male Etheostoma barrenense preferred models showing conspecific male coloration in a heterospecific pattern. In contrast, neither male nor female Etheostoma zonale showed a preference for models displaying conspecific colour or conspecific pattern. We speculate that colour may be under stronger sexual selection than pattern in E. barrenense, whereas colour and pattern may be equally important social cues for E. zonale.