Chapel Hill -- In 1862, British naturalist Henry Bates proposed -- but could not prove -- that over time, some animal and plant species that taste good to predators come to resemble other animals and plants that pose a danger to the hungry hunters.
By evolving in that way, the good-tasting species develop an effective defense mechanism and are more likely to survive and reproduce.
Although widely accepted and taught as early as elementary school, Batesian mimicry has remained unconfirmed. Now, however, a University of North Carolina at Chapel Hill scientist believes experiments he and others conducted with fake snakes strongly show the Englishman was right. Their report appears in the March 15 issue of the journal Nature. Authors are Dr. David W. Pfennig, associate professor of biology at UNC, undergraduate William R. Horcombe and Dr. Karen S. Pfennig, postdoctoral fellow at the University of Texas at Austin.
"What made Bates' idea so attractive and so unusual for its time was that there was no direct interaction between the dangerous species, which we call the model, and the mimic species," Pfennig said. "Instead, the evolution of mimicry was driven by the predators because if they didn't learn to avoid dangerous prey, they would not survive themselves. The ones that did survive were more likely to leave behind genes causing them to avoid danger."
The question became -- if you've got two species that look like each other -- how do you determine if it's really mimicry? he said.
"Lots of other nice studies of mimicry have been done, but we believe ours is the first to really test this critical prediction, which is that where there's no dangerous model present, then the protection from mimicry should break down," Pfennig said. "If the model that presents a risk is present, then there's very strong selective pressure to avoid the mimic."
In their experiments, he, his wife Karen and his student Horcombe relied on th
Contact: David Williamson
University of North Carolina at Chapel Hill