Predators drive the evolution of poison dart frogs' skin patterns

November 21, 2011
Research published in the American Naturalist by Université de Montréal's Mathieu Chouteau links the colors and patterns of poison dart frogs to their predators. Print resolution available. Credit: Mathieu Chouteau, Université de Montréal

Natural selection has played a role in the development of the many skins patterns of the tiny Ranitomeya imitator poison dart frog, according to a study that will be published in an upcoming edition of American Naturalist by University of Montreal biologist Mathieu Chouteau.

The researcher's methodology was rather unusual: on three occasions over three days, at two different sites, Chouteau investigated the number of attacks that had been made on fake frogs, by counting how many times that had been pecked. Those that were attacked the least looked like local frogs, while those that came from another area had obviously been targeted.

The brightly coloured frogs that we find in are in fact sending a clear message to : "don't come near me, I'm poisonous!" But why would a single species need multiple patterns when one would do? It appears that when predators do not recognize a poisonous frog as being a member of the local group, it attacks in the hope that it has chanced upon edible prey. "When predators see that their targets are of a different species, they attack. Over the long term, that explains how patterns and colours become uniform in an area," said Bernard Angers, who directed Chouteau's doctoral research.

A total of 3,600 life-size plasticine models, each less than one centimetre long, were used in the study. The menagerie was divided between two carefully identified sites in the . "The trickiest part was transporting my models without arousing suspicion at the airport and customs controls," Chouteau said. He chose plasticine following a review of scientific literature. "Many scientists have successfully used plasticine to create models of snakes, and poison dart frogs." The Peruvian part of the forest proved to be ideal for this study, as two radically different looking groups of frogs are found there: one, living on a plain, has yellow stripes, and the other, living on a mountain, has green patches. The two colonies are ten kilometers apart. 900 fake frogs were placed in each area in carefully targeted positions. Various combinations of colours and patterns were used.

Chouteau was particularly surprised by the "very small spatial scale at which the evolutionary process has taken place." Ten kilometers of separation sufficed for a clearly different adaptation to take place. "A second surprise was the learning abilities of the predator community, especially the speed at which the learning process takes place when a new and exotic defensive signal is introduced on a massive scale," Chouteau said.

This process could be at origin of the wide range of colour patterns that are observed not only in but also many species of butterflies, bees, and other animals. Mathieu Chouteau is in fact currently undertaking post-doctoral research into the Heliconius genus of butterfly. "Considering that this kind of project requires regular field work, I have taken up residence in the small town of Tarapoto, where I am responsible for the opening of a research centre that will facilitate the study of neotropical butterfly mimicry," he said.

Explore further: Vanishing cricket frogs get a look

More information: The Role of Predators in Maintaining the Geographic Organization of Aposematic Signals, American Naturalist: www.jstor.org/stable/10.1086/662667

Related Stories

Vanishing cricket frogs get a look

June 25, 2006

Researchers in the Chicago area are trying to track the vanishing population of cricket frogs, once so common they were hardly ever studied.

Amazonian amphibian diversity traced to Andes

March 10, 2009

Colorful poison frogs in the Amazon owe their great diversity to ancestors that leapt into the region from the Andes Mountains several times during the last 10 million years, a new study from The University of Texas at Austin ...

A newly discovered chemical weapon in poison frogs' arsenal

June 4, 2009

New research documents a surprising chemical weapon used by some Amazonian poison frogs. The study identified for the first time a family of poisons never before known to exist in these brightly colored creatures or elsewhere ...

Scientist finds rapidly adapting fanged frogs

August 16, 2011

(PhysOrg.com) -- Scientists led by biologist Ben Evans of McMaster University have documented the rapid adaptation of new fanged frog species on the island of Sulawesi, Indonesia.

Recommended for you

Research advances on transplant ward pathogen

August 28, 2015

The fungus Cryptococcus causes meningitis, a brain disease that kills about 1 million people each year—mainly those with impaired immune systems due to AIDS, cancer treatment or an organ transplant. It's difficult to treat ...

Genomes uncover life's early history

August 24, 2015

A University of Manchester scientist is part of a team which has carried out one of the biggest ever analyses of genomes on life of all forms.

Rare nautilus sighted for the first time in three decades

August 25, 2015

In early August, biologist Peter Ward returned from the South Pacific with news that he encountered an old friend, one he hadn't seen in over three decades. The University of Washington professor had seen what he considers ...

0 comments

Please sign in to add a comment. Registration is free, and takes less than a minute. Read more

Click here to reset your password.
Sign in to get notified via email when new comments are made.