Snake Camouflage Deters Predators.

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Harmless snakes using the colors of dangerous species to protect themselves from predators can successfully get away with this strategy--but only in areas where deadly snakes are found, according to researchers at The University of Texas at Austin and the University of North Carolina at Chapel Hill. Their studies add new weight to the evidence for natural selection.

The researchers focused on predator behavior toward extremely poisonous coral snakes, noted for their ringed markings of red, black, and yellow, or red, black, and white, along with their harmless imitators, the kingsnakes. The theory of Batesian mimicry holds that edible species that look like dangerous species will be protected, because predators evolve to avoid dangerous species--even without previous, real-life, bad dining experiences.

"Mimicry has been used as the preeminent example of how natural selection works and why it works the way it does," indicates Karin Pfennig of the University of Texas' College of Natural Sciences. "There is very strong selection for predators to avoid snakes with these kinds of ringed patterns because they look dangerous. This is probably not based on predators having previous experience with coral snakes, because all it takes is one bite and you're dead. You're out of the gene pool."

The researchers predicted that the protective effect of looking like a coral snake would break down in those areas where poisonous coral snakes were absent. Under such circumstances, the process of natural selection would not operate to eliminate heedless predators. There would be no need for color-conscious predators to evolve.

To measure predator attacks, the researchers and their assistants constructed about 1,200 fake snakes composed of nontoxic plasticine threaded onto an S-shaped wire. They used caulk guns to squirt out appropriately sized tricolor, striped, and plain...