On the U-M Gateway: Mimicking venomous snakes: untangling the history of deceptive coloration


By EEB
Jul 03, 2013 Bookmark and Share

Alison Davis Rabosky holding several ground snakes, a non-venomous species that displays four strikingly different color patterns. Rabosky is breeding ground snakes in her lab to understand the genetics behind the color variation in mimicry systems. Credit: Eric Bronson, Michigan Photography

Alison Davis Rabosky holding several ground snakes, a non-venomous species that displays four strikingly different color patterns. Rabosky is breeding ground snakes in her lab to understand the genetics behind the color variation in mimicry systems. Credit: Eric Bronson, Michigan Photography

Wednesday, July 03, 2013

Red on yellow, kill a fellow. Red on black, friend of Jack.

That folk rhyme is supposed to help people distinguish venomous coral snakes from several non-venomous "mimics," animals that discourage predators by deceptively imitating a dangerous species.

Problem is, the rhyme is unreliable due to the vast amount of color and pattern variation, called color polymorphism, found in both coral snakes and their mimics. The harmless ground snake, a common coral snake mimic, displays four strikingly different color patterns, only one of which closely resembles its dangerous red-and-black-and-yellow-banded counterpart.

If a mimicry system offers protection from predators, then why hasn't evolution eliminated the "failed mimics," such as ground snakes sporting color patterns that don't remotely resemble a coral snake? That's the puzzle that U-M evolutionary biologist Alison Davis Rabosky has spent the last four years trying to solve.

Rabosky is an assistant research scientist in the Department of Ecology and Evolutionary Biology and an assistant curator of herpetology at the Museum of Zoology who worked with Christian L. Cox of the University of Virginia. They don't claim to have fully resolved the paradox, but they did gain insights that help explain the persistence of non-mimic color patterns in ground snakes, especially rare patterns. Their findings were published online June 26, 2013 in The American Naturalist.

Read about their findings in the U-M News Service press release and watch for a forthcoming EEB research feature.

In this article:

Davis Rabosky, Alison

The four color patterns, which are called morphs, found in the ground snake

The four color patterns, which are called morphs, found in the ground snake: plain brown, red stripe down the back, black-banded on a light gray background, and the red-and-black-banded "mimic morph," which resembles the venomous coral snake. Credit: Alison Davis Rabosky.