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The secret lives of frogs

Ana Carolina Carnaval / UC-Berkeley
The frog Hypsiboas semilineatus is found in Brazil's Atlantic rainforest.

This has been a fantastic week for frogs, and the scientists who love them.

First, there was a report that as many as 10 new species of amphibians have been discovered in the jungles of Colombia. Then, a frog-finding duo said they found a dozen new species in the forests of India. Finally, researchers published promising results from an experiment that used DNA from nearly 200 Brazilian tree frogs to help identify the hottest biodiversity hot spots.

Marco Rada / CI-Colombia
Click for slideshow: See the
new amphibian species discovered in Colombia's Darien region.


The week's findings demonstrated that there's still lots to learn about the world's amphibian species - and that even tiny frogs can make a big contribution to global environmental awareness.

Frogs and other amphibians could use a bit of good news: They're facing challenges ranging from climate change to fungal infections to a mysterious wave of deformities. Habitat loss is the biggest factor working against them, and it doesn't help that they're so darn delicious.

Robin Moore, amphibian conservation officer for Conservation International, told me that he takes heart from the discovery of new species like the ones found in Colombia's Darien region. "The fact that these areas still exist shows that we still have time, and we still have a chance," he said.

Which hot spots are hottest?
Conservation International has identified 34 hot spots around the world that take in only 2.3 percent of Earth's land surface, and yet serve as native territory for more than 50 percent of the world's plant species as well as 42 percent of all terrestrial vertebrate species. All these areas deserve to be preserved from environmental degradation - but how do you prioritize one area (or even one part of one area) over another?

Ana Carolina Carnaval / UC-Berkeley
Hypsiboas albomarginatus was one
of the three frog species that
figured in the Science study.


The research from Brazil, published in today's issue of the journal Science, suggests one method: First, researchers developed a computer model to determine which areas have had the most stable climate over time. Then they looked for a way to measure the amount of biodiversity in those areas.

Their hypothesis was that in the more stable areas, native species have had more time to spread out and reflect genetic diversity - while the species currently living in the less stable areas haven't been around as long and thus would be less diverse.

Brazil's Atlantic forest region, one of Conservation International's hot spots, served as a test case. The model indicated that the region's central rainforests were more stable climatically than the southern forests, going back as far as 21,000 years. That suggested that the biodiversity would be greater in the north than in the south.

To check the hypothesis, the researchers took DNA samples from 184 tree frogs representing three different species. Sure enough, an analysis of mitochondrial DNA showed less genetic diversity in the south than in the central area. The researchers confirmed that assessment by reviewing previously published genetic data for mammals and reptiles. Bird studies showed a similar pattern.

Ana Carolina Carnaval / UC-Berkeley
Hypsiboas faber was another one
of the Brazilian frog species
sampled for the Science study.


"The study has shown us that the central Atlantic forest, which hasn't had the investment of resources and effort as the southern, has been stable from a climatic standpoint and therefore is likely more diverse than currently believed," study co-author Craig Moritz, a biologist at the University of California at Berkeley, said in a news release. "But because this area is under great human impact, it deserves conservation and research priority."

That doesn't mean the southern forests aren't important, said Berkeley's Ana Carolina Carnaval, another one of the study's co-authors. But it does mean there can be a hidden dimension to biodiversity - at least in the hot spot she and her colleagues analyzed.

"The broader story is that we think this technique could be applied in other countries and other hotspot areas to identify regions that haven't been well-sampled yet - regions that could possibly harbor as yet undiscovered unique diversity," she said.

New frogs by the dozen
Based on this week's findings, the forests of India's Western Ghats might qualify as one of those regions. It's already listed, along with Sri Lanka, as a Conservation International hot spot. But the fact that researchers reported 12 new frog species in the Zoological Journal of the Linnean Society indicates that lots of secret lives are playing out in that region.

It wasn't easy to find all those frogs, one of the researchers told me by e-mail. "You can study the animals only during the night," said Sathyabhama D. Biju, an expert on amphibians at the Delhi University Systematics Lab. What's more, the best time to find them is during the monsoon season, which is their breeding time.

S.D. Biju / Frogindia.org
Click for slideshow: See the 12
frog species discovered in India.


"It is difficult and at the same time enjoyable too," Biju wrote. "Seeing new frogs croaking in the dark nights with torrential rain is really good!"

Seven of the 12 new species were discovered in unprotected areas that were once heavily forested, according to Biju and his co-author, Franky Bossuyt of the Amphibian Evolution Lab at Vrije Universiteit Brussel. The duo also rediscovered the Travancore bushfrog, a species that was last officially sighted more than 100 years ago and was thought to have gone extinct. They said the frog was found in "a highly degraded environment in its original locality."

Biju said that frogs in India, like frogs in South America, are considered an important indicator species for the health of an ecosystem. And he's deeply concerned about forest-clearing in the Western Ghats, where some of India's best-known tea, coffee and rubber plantations are located.

"It is a shame that human interference like plantation (legal and illegal) near the forest, and urbanization (for the sake of so-called development) contribute to rapidly vanishing habitat," he wrote. "Really, I am worried about my frogs."


Co-authors of the study in Science include Carnaval and Moritz as well as Michael Hickerson of Queens College, New York; Celio Haddad of Universidade Estadual Paulista; and Miguel Rodrigues of Universidade de Sao Paulo. To keep track of biodiversity and other big environmental issues, check out msnbc.com's Environment section.