Resembling the juvenile colour of host cichlid facilitates access of the guest cichlid to host territory

Abstract

AbstractIn two coexisting species with similar body colours, one species may acquire benefits from mimicking the body colour of the other species. In Lake Tanganyika, the zoobenthivorous cichlid Neolamprologus mustax preferentially exploits the territories of the algivorous cichlid Variabilichromis moorii as a feeding ground, even though other zoobenthivorous cichlid species are expelled from these territories. The yellow body colour of the guest species, N. mustax, resembles that of juveniles of the host species, V. moorii, adults of which have entirely black bodies. To estimate the effect of juvenile colour on aggression from conspecific adults, the responses of adult V. moorii to dummy fish of four colours (black, yellow, white, and blue) were observed in this lake system. Our observations clearly demonstrated that adult V. moorii were less aggressive toward yellow, white, and blue dummies compared to black ones, with a slight difference in response to the yellow and white or blue dummies. This study indicates that resembling the colour of host juveniles can facilitate access of the guest species to host territory, but does not provide sufficient evidence for a hypothesis that the guest species mimics the body colour of the host juvenile.