Guppy love

Natural History, July-August, 2002 by Stephan Reebs

During courtship, female guppies are attracted to green, black, and especially orange spots on the flanks of mates. F. Helen Rodd, of the University of Toronto, and colleagues suggest that this color preference may have arisen from a taste for orange food. On the island of Trinidad, they watched guppies voraciously feeding on the rare and highly nutritious orange fruits of the cabrehash tree (Sloanea laurifolia), some of which had fallen into streams. After placing artificially colored disks in the water, the biologists observed that females (and males, too, though to a lesser extent) approached and pecked at orange disks more than at disks of any other color--with red a close second. Moreover, a comparison of six different guppy populations revealed a strong correlation between the strength of females' preference for males with bright spots and females' rate of pecking at orange objects. The population in which the females were most often attracted to males with the brightest orange spots, for example, was also the one in which females pecked most vigorously at orange disks. Because orange objects in nature are likely to be food, perhaps in the course of guppy evolution the way to a female's heart has been through her eyes ... and her stomach. ("A Possible Non-Sexual Origin of Mate Preference: Are Mate Guppies Mimicking Fruit?" Proceedings of the Royal Society of London B 269, 2002)

Stephan Reebs is a professor of biology at the Universite de Moncton in New Brunswick, Canada, and the author of Fish Behavior in the Aquarium and in the Wild (Cornell University Press).