Impersonating poisonous prey

Mar 10, 2014
MSU scientists show that nontoxic imposters, like king snakes, benefit from giving off a poisonous persona, even when the signals are not even close. Credit: Courtesy of MSU

Imitation is the most sincere form of flattery – especially in the predator/prey/poison cycle.

In nature, bright colors are basically neon signs that scream, "Don't eat me!" But how did evolve these characteristics? When did predators translate the meaning?

In the current issue of the journal PLOS ONE, researchers at Michigan State University reveal that these color-coded communiqués evolve over time through gradual steps. Equally interesting, the scientists show how drab-colored, oft-eaten prey adopt garish colors to live long and prosper, even though they aren't poisonous, said Kenna Lehmann, MSU doctoral student of zoology.

"In some cases, nonpoisonous prey gave up their protection of camouflage and acquired bright colors," said Lehmann, who conducted the research through MSU's BEACON Center for the Study of Evolution in Action. "How did these imitators get past that tricky middle ground, where they can be easily seen, but they don't quite resemble colorful toxic prey? And why take the risk?"

They take the risk because the evolutionary benefit of mimicry works. A nontoxic imposter benefits from giving off a poisonous persona, even when the signals are not even close. Predators, engrained to avoid truly toxic prey, react to the impersonations and avoid eating the imposters.

An example of truly toxic animals and their imitators are coral snakes and king snakes. While coral snakes are poisonous, king snakes are not. Even though king are considered imperfect mimics, they are close enough that predators don't bother them.

Why don't all prey have these characteristics, and why don't the imitators evolve to develop poison instead? Leaving the safety of the cryptic, camouflage peak to go through the exposed adaptive valley over many generations is a dangerous journey, Lehmann said.

"To take the risk of traversing the dangerous middle ground – where they don't look enough like toxic prey – is too great in many cases," she said. "Toxins can be costly to produce. If prey gain protection by colors alone, then it doesn't make evolutionary sense to expend additional energy developing the poison."

The results suggest that these communicative systems can evolve through gradual steps instead of an unlikely large single step. This gives insight into how complex signals, both sent and received, may have evolved through seemingly disadvantageous steps.

Rather than conduct experiments of voracious predators chasing and eating, or completely avoiding, prey, the scientists used evolving populations of digital organisms in a virtual world called Avida.

Avida is a software environment developed at MSU in which specialized computer programs compete and reproduce. Because mutations happen when Avidians copy themselves, which lead to differences in reproductive rates, these digital organisms evolve, just like living things.

Explore further: Why are some snakes so venomous?

add to favorites email to friend print save as pdf

Related Stories

'Ghost' fish taking over the Caribbean

Oct 18, 2013

(Phys.org) —A spiny, toxic and beautiful member of the world's coral reef communities, the Red Lionfish is invisible to the small fish it likes to eat.

Crittercam captures crocodilian foraging behaviors

Jan 15, 2014

Animal-borne camera reveals that alligators may attempt to capture prey most often at night, even though the calculated probability of catching prey is highest in the morning, according to a study published ...

Recommended for you

User comments : 1

Adjust slider to filter visible comments by rank

Display comments: newest first

GSwift7
5 / 5 (1) Mar 11, 2014
Toxins can be costly to produce. If prey gain protection by colors alone, then it doesn't make evolutionary sense to expend additional energy developing the poison


Not to mention that if the imposter were to develop poison, then they would be competing with the original over the same niche of prey. Only developing the colors, without the poison, allows them to share the same habitat without directly competing for food.