A rare breed, indeed

Smithsonian researchers breed tiny poison dart frog
This tiny poison dart frog is smaller than a dime. Photo courtesy of Smithsonian National Zoo
This dart frog was discovered last year and is very rare. It is only found in the rainforest in a tiny area of central Panama. Photo courtesy of Smithsonian National Zoo

Researchers with the Smithsonian Conservation Biology Institute in Front Royal recently helped in the successful captive breeding of a rare Panamanian species of poison dart frog.

This development is part of an ongoing project called the Panama Amphibian Rescue and Conservation Project, which includes Smithsonian researchers.

Smithsonian researcher and project director Brian Gratwicke expressed excitement over the successful breeding of the species known as Andinobates geminisae.

“It’s just neat to learn about the natural history of an animal in these captive situations,” Gratwicke said.

The breeding of this species, Gratwicke explained, was in response to “potential habitat modifications” occurring in that area of Panama.

Gratwicke said they were worried about the potential modifications, so they “took two frogs out of the forest, to just see if we could breed them, and they bred right away.”

This species of frog is actually different than most frogs, Gratwicke said, in terms of how it breeds.

“With most frogs, you get them to lay a bunch of eggs and then all of a sudden you have a bunch of tadpoles,” he said, “With this frog, they lay their eggs sort of one-at-a-time.”

Gratwicke said he thinks this is related to “the fact that they’re restricted to breeding in little tree holes … or something.”

According to Gratwicke, this species was only just discovered — or described — to scientists late in 2014.

“It’s a pretty neat little frog in that it’s really, really tiny,” Gratwicke said, explaining that it “only grows to about the size of your pinky finger nail.”

The frog is also extraordinarily rare. Gratwicke said that it “only occurs in the rainforest in a very, very tiny area of central Panama.”

Outside of the frog’s distribution and rarity, Gratwicke said, “We know nothing about its natural history [and] we don’t even know if it is susceptible to this chytrid disease.”

Over the years, researchers have noted that the chytrid fungus — or chytridiomycosis — has caused rapid population declines and, in some cases, even the extinction of certain amphibious species.

According to Gratwicke, one of their collaborators at the University of Massachusetts in Boston, Doug Woodhams, has recently developed a new method for testing chytrid fungus on frogs.

“He has developed a technique, where you can basically put the frog in a little, tiny bit of water and then give it a prolonged rinse,” Gratwicke said.

After that, scientists can “look at all of the metabolites in that rinse water and see if they inhibit growth of chytrid in a broth.”

With this method, Gratwicke said, “You would never have to expose the frog to the chytrid fungus. It’s a pretty humane way to actually measure the susceptibility of a species.”

Although Gratwicke noted that this species is not being tested for chytrid at the moment, he said, “I sort of have it in the back of my mind that we’ll ask Doug to come down and see if he could try … this new test.”

From here, Gratwicke said they will probably be looking to get more frogs in order to have a larger in-captive population — or what is called a “genetically viable population.”

“In order to do that, you really need to capture 10 male and 10 female frogs in a second generation and you need to breed those out,” Gratwicke said.

This population would essentially allow researchers to preserve “95 percent of the genetic variation in the species over 1,000 generations” in captivity.

It would also allow researchers to observe natural behaviors of this species of dart frogs.

As an example, Gratwicke explained that one aspect of this species researchers are unclear on is which parent “carries the tadpole on its back” once it has hatched.

Gratwicke said this is done by some species of poison dart frogs in order to “find a suitable” pool inside of a tree to place the tadpole.

“We haven’t actually been able to observe whether that’s the male or the female,” Gratwicke said. “I hope that we’ll learn that soon enough in our captive breeding populations.”

Contact staff writer Kevin Green at 540-465-5137 ext. 155, or kgreen@nvdaily.com

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