Poison Frog Uses Less-Toxic Looks to Survive, Study Finds

March 8, 2006

Many animals avoid being eaten by copying the appearance of their poisonous neighbors. But when it comes to deciding whose looks to mimic, an Amazonian poison frog is teaching biologists a new lesson about this evolutionary trick.

Instead of copying its most poisonous and numerous neighbors, a nontoxic species of poison frog in Ecuador has been found to get better protection from predators by looking like a less abundant frog that packs a less toxic punch.

The finding may make scientists rethink the laws of Batesian mimicry, as the copycat safety strategy is known, said Catherine Darst, a graduate student in biology at the University of Texas at Austin.

"We found another way that Batesian mimicry works," she said.

According to Darst, the way predators learn to avoid toxic prey can drive the evolution of the copycats' color patterns.

The more toxic frogs are so nasty that predators quickly learn to avoid anything that remotely resembles them, she explained. But predators that eat the less toxic frogs learn to only avoid that species and its exact mimics.

Since all the frogs look similar, the mimics can afford an imperfect match with the more toxic species and gain the advantage of looking just like the less toxic frog, Darst said.

She and colleague Molly Cummings, a University of Texas biology professor, report the discovery in tomorrow's issue of the science journal Nature.

David Pfennig, who studies snake mimics at the University of North Carolina at Chapel Hill, said the findings may seem counterintuitive, but they "make sense."

"These results are likely general to other systems as well," he said.

"There should be a larger cone of protection around more toxic species," which gives mimics room to evolve new color patterns.

Copycat Protection

Continued on Next Page >>


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