Mimicry is key for butterfly survival

A yellow Heliconius cydno butterfly from the rain forests of northwestern Ecuador

By Environmental News Network staff

In the butterfly world, collaboration is a key survival tactic.

Though they do not come from the same species, three South American butterflies strongly resemble one another and share many secrets, according to a recent study in the journal Nature.

Durrell Kapan, a biology researcher at the Universidad Rio Piedras in Puerto Rico, based his research on the idea established by German naturalist Fritz Müller.

In 1879, Müller proposed that two unrelated noxious butterflies that share similar warning colors benefit because they spread the burden of educating predators to avoid them. Kapan is the first scientist to test that theory in the field.

Supported by a team of volunteers from the Earthwatch Institute, Kapan examined mimicry among a collection of Heliconius butterfly species that live in the rain forest in western Ecuador.

As living "stop signs," certain foul-tasting species of butterflies exhibit similar color patterns that tell predators to keep their distance, Kapan explained. When several species display the same "stop-sign," they share the number of sacrificed butterflies to teach predators that all butterflies of that color taste bad and are to be avoided.

Predators also benefit because they have to learn only one signal to discriminate which species to avoid instead of having to learn separate cues for each bad-tasting species.

Durrell Kapan, a biology researcher at the Universidad Rio Piedras in Puerto Rico, documents the start of his study, gently marking a butterfly's wing with a unique number before releasing it

The intricate connection between certain butterfly species may have profound implications for their future survival.

All three of the butterflies live in a rapidly vanishing ecosystem.

In 1988, only 8 percent of the low-elevation primary forest that the butterflies depend on remained in western Ecuador, Kapan said. "This figure has probably halved again in the past 12 to 13 years. From the point of view of unique species at risk of extinction it may be the most imperiled area in all of the New World."

While each species of butterfly has a different level of dependence on rain forest habitat, the destruction of one species could have a direct effect on the survival of other species.

"We do not know what would happen if the mimicry relationship is broken because of forest destruction," Kapan said. "The loss of mimicry due to the loss of one of these butterflies could accelerate the demise of the remaining species."

Copyright 2001, Environmental News Network, All Rights Reserved

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