Dietary carotenoids and male mating success in the guppy: an environmental component to female choice

Summary This study examined the relationship between dietary carotenoids, female choice, and male mating success in the guppy, Poecilia reticulata. Using a split-brood design, male siblings were either raised on a diet enhanced with astaxanthin and canthaxin or fed a basal diet without carotenoids. Males were photographed, and the location, size, and brightness of their red and orange pigment spots on the body were measured. Courtship behaviors were recorded during visual and mating trials. Males fed the carotenoid-enhanced diet had red and orange spots that averaged 2.5 times brighter, spent significantly more time near the female in visual response trials, were preferred by females in visual choice tests, and had a higher mating success than their siblings raised on the carotenoid-free diet. Diet did not affect male size, location or size of the red and orange pigment spots, or the intensity of courtship behavior. The results of this study show that females respond to environmentally-induced variation in the expression of a secondary sexual trait and that this has important consequences for male mating success.