Meeting Abstract
P3.188 Tuesday, Jan. 6 Male Cichlid Colors as Conspicuous Signals in Lake Malawi: The Fish’s Perspective DALTON, B.E.*; CARLETON, K.L.; MARSHALL, N.J.; CRONIN, T.W.; University of Maryland, Baltimore County; University of Maryland, College Park; University of Queensland; University of Maryland, Baltimore County briand7@gmail.com
Cichlids in Lake Malawi have diversified rapidly, forming 500 to 1000 species in approximately the last million years. Although the responsible speciation mechanisms have yet to be firmly established, sexual selection is likely involved. In the rock-dwelling clade (known as mbuna) male territoriality and asymmetrical reproductive investment by mouthbrooding females are typical. We hypothesize that if sexual selection is driving this diversification, males will be more conspicuous than females. Indeed, closely related species differ primarily in male nuptial coloration. Previous analyses of mbuna colors were biased by human perception, however. Relative to human vision, mbuna spectral sensitivity is shifted toward shorter wavelengths, including the UV. Using a trichromatic color space model, we compared the conspicuousness of male and female colors in nine species from the perspective of their own visual systems. Conspicuousness of a color was evaluated as its distance in color space from viewing backgrounds and from other colors on the same fish. Male colors generally appeared more conspicuous than female colors in most contexts. The blue and yellow colors typical of male mbuna contrasted well with each other and with the backgrounds. Interestingly, in three species female colors were more conspicuous than male colors in some viewing contexts. We also revealed that effects of changing illumination due to water depth can be countered by simple mechanisms of color constancy. These results suggest that male mbuna colors could function as conspicuous signals in a broad range of viewing conditions found in their habitat, consistent with sexual selection as an important diversifying force.
