Brightly colored prey generally signify danger in the form
of toxins for the predator. Predators instinctively know that a brightly
colored prey is a sign of bad news and not a suitable meal. Researchers at
Michigan State University however are exploring how this evolved and in the
process found some animals have actually only imitated the trait in an effort
to survive event though they are not poisonous.
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According to Kenna Lehmann, MSU
doctoral student of zoology, “In some cases, nonpoisonous prey gave up their
protection of camouflage and acquired bright colors.” Her research was
conducted through MSU’s
BEACON Center for the Study of Evolution in Action. She wondered,
“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 snakes 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.
Read more at Michigan
State University Today.
Coral Snake and King Snake images via Shutterstock; combined by Robin Blackstone.