New Poison Frog Species Evolving Before Our Eyes, Study Says

A poison dart frog from Peru that mimics its neighbors in incredible detail is evolving into a new species, scientists believe. 

The mimic frog (Ranitomeya imitator) is the first vertebrate, and only the second known animal, to suggest that mimicry can split populations into separate species, according to a study published recently in Nature Communications. The other animal is a group of Heliconius butterflies, which are also found in South America.

Photo of a imitator varadero frog.
Ranitomeya imitator, dubbed Varadero, a poison dart frog that mimics its neighbor R. fantastica, is seen in San Gabriel de Varadero, Peru. Photograph by Evan Twomey

We can’t hold the frog in our hands just yet, though—the new species may not finish evolving for several thousand more years.

freshwater species of the weekSeparate geographic populations of R. imitator can look wildly different, depending on the frog species they’re mimicking. In north-central Peru, two R. imitator populations colorfully masquerade as two contrasting poison frog species: The splash-back poison frog (R. variabilis) or red-headed poison frog (R. fantastica). (See more pictures of poison dart frogs.)

In a phenomenon known as Müllerian mimicry, which occurs when two or more poisonous or unpalatable species adopt the same colorful warning signal to predators, one of the R. imitator morphs—called “striped”—takes on the black-and-yellow stripes and marbled aqua legs of R. variabilis.

The other morph, or type—dubbed Varadero—has the orange head, black splotches, and blue legs of R. fantastica.

The study found that where these R.imitator morphs, which usually live apart, come into contact, the process of forming a new species begins.

Sticking With Their Own

The early signal of this process is that the two R. imitator morphs prefer to mate with their own type, according to the team’s observations in the wild.

In the experiments, scientists gave courting males the choice of a female from each morph, and then recorded the amount of courtship time between the male and each of the two female morphs to measure their preference.

“We think this will lead to speciation”—the process in which new species evolve—”but we’ll have to come back in a few thousand years to be sure,” said study co-author Kyle Summers, an evolutionary biologist at East Carolina University in Greenville, North Carolina.

R. variabilis, one of the species mimicked by R. imitator, from the Cainarachi Valley, Peru. Photograph by Evan Twomey

Evidence that the morphs prefer to hook up with their own kind “suggests there has been some sort of negative consequence of breeding with the wrong morph,” said Summers, who received funding from National Geographic’s Committee for Research and Exploration.

Maybe “their offspring are less fit or they are more likely to be predated,” he added. “They have evolved this preference, but only where they’re likely to be at risk of making a mistake.” (See “New Frog Found—Has ‘Striking’ Color Change.”)

What’s more, the frogs’ ability to imitate is driving their genetic separation, the study team suspects, because the two morphs can use their elaborate patterns to tell each other apart.

Summers and colleagues’ past and ongoing studies into the vision of poison dart frogs make him “fairly confident that they can see the color pattern differences quite clearly,” he said.

Fascinating Link

James Mallet, an evolutionary biologist at Harvard University in Cambridge, Massachusetts, said that R. imitator’s ability to dramatically mimic different color patterns within various parts of its range is “amazing” and “very similar to what is happening in Ecuador and eastern Peru in the Heliconius butterflies.”

Photo of a fantastica varadero frog.
 R. fantastica, the second species whose color is mimicked by R. imitator, seen in Varadero, Peru. Photograph by Evan Twomey

Mallet, who wasn’t involved in the new study, added that the finding that R.imitator’s mimicry switching is shown to be associated with mating behavior is “fascinating” and “gives an argument” for a new species in process.

But Mallet said that while color patterns are known to influence the mating decisions of some poison dart frogs, the new study “did not present any data showing that mate choice was based on color.” (See “Wild Romance: Weird Animal Courtship and Mating Rituals.”)

The distinct morphs “may be using some different signals, such as song,” he added.

Dealing with these frog masters of disguise, it was always going to be difficult to tell.

James Owen is a journalist and author based in Stockholm, Sweden. After cutting his teeth on the news and features desks of several UK newspapers, he struck out as a freelance writer, specializing in life sciences and natural history. His fish biography 'Trout' (Reaktion Books) was published in 2012.
  • Luiz Rocha

    The very first sentence of this article (and perhaps the boldest claim of the paper) is incorrect. Mimicry has been suggested as the main driver of speciation in several fishes (which are also vertebrates). Here is just one example: http://rspb.royalsocietypublishing.org/content/274/1615/1265

  • James Wesley


    There has also been research that suggest that Ranitomeya imitators to be monogamous in the wild.

  • Michael Stypko

    This only means that they are genetically predisposed to mate with frogs that have the same morph, how are they evolving into a new species? The only distinct trait is the coloration. There are other dart frog species who have different coloration but are the same species, right?

    • James Owen

      Hi Michael, the study authors argue that these frogs are at an early stage of speciation where reproductive isolation – an essential condition if a new species is to form – is becoming evident. Actually, if I understand correctly, these two R. imitator mimic morphs that live in areas where the two wouldn’t expect to run into each other don’t show a mating preference, despite their different patterning. It’s only in the very small area where the two morphs come into contact that a preference seems to have evolved. In this so-called “transition zone” the two morphs also show evidence of other differences, including in their mating calls, the study found.

      And yes, there are various other poison frog species that show a range of color patterns (including, I think, the poison frog species that these two R. imitator morphs are mimicking) but that doesn’t in itself mean they’re likely to evolve into new species.

  • John Pistachio

    Is any genetic work being done on these two morphs? I’m guessing it is far too early to notice any differentiation yet phylogenetically, but I’m at least interested in seeing how their genetic divergence compares even at this early stage. Especially given the fact that cryptic species complexes are quite common in amphibian populations and can potentially complicate this analysis.

  • Marco

    I doubt it means evolution.The process of speciation can be enhanced and completed by altering the prevelance of allels in two different populations to that level they wont mate. Evolution is needless for this purpose. It happend with human guidance in canidaes so for instance Doberman Pinscher can’t natrually reproduce with miniature Pinscher though they are both very much the same.

  • James Owen

    In answer to John, yes the study team did run some genetic analyses. The results showed evidence of genetic divergence between the morphs associated with color pattern rather than geographic distance, and suggests reduced gene flow between the morphs when they come into contact. Here’s the study link if you’d like more info: http://www.nature.com/ncomms/2014/140827/ncomms5749/full/ncomms5749.html

  • Raúl Picaporte

    I’d like to ask if you can give a simple yet thorough explanation of how R. imitator changes color, how long this takes, and the chemical factors involved, including the specific nutrients required to make the color variations. I would guess the flow of different chemicals would eventually contribute greatly to the transformation of physical structures. At the same time, I’d like to ask if you think there is a relationship between this differentiation and possible speciation and the genealogy of the different human races.

  • C.B.Ross

    Am I correct is saying that, at the end of the “several thousand years” this creature will still be a frog?!

  • D Smith

    I must have first thought that this was a Creation article pointing out how secular scientists are Wrong Again in their interpretation of the facts about this Frog Species evolving. What some secular scientists would say is “evolving” is actually mutation or variation of a species, or what they would call “micro-evolution” which does happen, but it is still “a frog”. There is not, nor has there ever been any observable examples of evolution or changing from what the Bible calls “kinds.” There has never been an observable example of one “kind” changing to another “kind,” such as a reptile changing into a bird. A frog is still a frog, a finch is still a finch, a moth is still a moth, a bacteria is still a bacteria. There is a difference between “Observational Science” and “Historical Science.” We cannot observe what has happened in the past history. We can only have presuppositions based on our individual world views. The “belief” in the possibility of “microbes to microbiologist evolution” has never been observed, and is not science, but it is a presuppositional theory or world-view, or a religious belief that is a matter of the persons “faith” in this idea, and has nothing to do with any observable science.

  • DarrelX

    There is absolutely nothing in this article that proves macro-evolution to be a fact or Abiogenesis for that matter. Given the insurmountable gap between dead matter and life. The irreducible complexity of life on every level, species and organs’ and the fact that only life can create life (and I challenge you to prove otherwise) this is just another emperor’s new clothes spin by evolutionist.

  • Zachary

    I think it is a amazing creature

  • Franck Merlot

    The confirmation bias of the religious commenters is blatant. Certain people are unable to appreciate the fact that this is an important scientific finding. It does in fact reinforce the plausibility of evolution.

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