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July 18, 2018

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From discovery to extinction: After 650,000 years roaming Nevada, newly discovered toad could be at risk


Courtesy of Patrick Donnelly

The Dixie Valley Toad has golden skin and large poison pouches.

Around the world, new species of amphibians are discovered almost every other day, according to C. Richard Tracy, an ecologist at UNR. In the United States though, these discoveries are rare, which made his lab’s recent identification of a new toad species a special find. But ever since publishing his findings in the peer-reviewed journal Zootaxa, Tracy has been raising the alarm about the future of the gleaming gold-speckled amphibian — the Dixie Valley toad — that roams the Great Basin. A month later, there is already a petition to list it as endangered.

“This toad is a beautiful toad,” Tracy said. “It’s not your average toad.”

Tracy said he cared about all toads, but this specimen had unique qualities — shiny golden skin and especially large poison pouches.

The Sunday met with the scientist, and he answered questions about discovering a new species, conservation and threats to the Dixie Valley toad.

How rare is this?

That depends on where you’re looking. In 2016, scientists around the world discovered about 18,000 new plants and animals. Of those, Tracy estimated that about 200 were amphibian species, and that a comparable number was discovered every year. But in the United States and Canada, the numbers drop off.

Tracy said the best estimates he could find suggested that scientists in those two countries had discovered only two bird species in the past 50 years, no new mammals and about three amphibians. It’s not that there is less biodiversity, Tracy says; many U.S. biologists have simply already discovered a great number of species.

Adding species to our library is good, right?

Discovering species can expand our knowledge, but don’t let that negate the fact that, in Tracy’s words, “We are losing species, especially amphibians, at a very rapid rate.”

A fungal disease has affected several amphibian populations. Other factors driving the extinction rate include climate change and habitat lost to human development. Amphibians are going extinct much faster than any other terrestrial invertebrate, Tracy said.

“You go into the library and walk around through the stack of books,” Tracy said. “And you discover a book. And you think, wow, that’s a neat book. That book was always there, and now you’ve discovered it. But if someone is taking books from the library and throwing them onto a blazing fire, then they’re gone forever. … They’re two completely different processes. Extinction is a permanent process. Finding a new species is an amazing thing, but it was something that was always there. In the case of the Dixie Toad, we know it’s been there for 650,000 years.”

Did you say 650,000 years?

A geology master’s student was assigned to investigate the paleohydrology to see when the toad wound up in the Northern Nevada valley for which the species was named. The student looked to see when Lake Lahontan last connected to the area, and wound up with a 650,000-year estimate. “That’s when our toad separated from the toad we can now find in the Humboldt/Lahontan area,” Tracy said. “That’s before humans were even humans.”

And it’s threatened?

A proposed geothermal project could damage the toad habitat by pumping billions of gallons of water out from an underground reservoir. Because of the project — the plans are under review by the Bureau of Land Management — conservationists want the toad listed as endangered. The Tucson, Ariz.-based nonprofit Center for Biological Diversity is petitioning the federal government to protect the species.

“That toad has been there 650,000 years. It’s a full species as much as we are a full species or the bald eagle is a full species,” Tracy said. “There’s no way we would allow the bald eagle to go extinct because we want some power plant to go in. ... The people of the United States care about species, so they endorsed the existence of the Endangered Species Act.”

While there has been conversation about restraining or “modernizing” the act, repealing it doesn’t appear to be on the table in any serious way.

What’s the value of keeping one species from disappearing?

Tracy, who teaches a class on extinction, said there were many answers. including ethics and ecosystem connectivity. But he also said there was a compelling case that biodiversity could help spur economic development.

“Toads have poison glands, and every species has a slightly different chemical structure in its poison glands,” he said. “And toxins from poison glands in general turn out to be of pharmacological value.” He cited the example of a new frog species found in South America. “You might say, ‘What’s the value of this frog?’ Well, they found that the mucus produced by this frog can actually kill H1 flu virus. Here’s a species that could actually do away with flu.”

So how does one find a new species?

In this case, it was dedicated field research.

For a separate project, one of Tracy’s students cataloged toads in most of the Western Great Basin, including the Mojave Desert and Northern Nevada. He took tissue samples from the webbing between the toads’ toes. After the student left for a teaching job in New York, Tracy did genetic testing on the samples and discovered a divergence when it came to three of the samples. In addition to the Dixie Valley toad, Tracy found two other new species in Northern Nevada.

Once it’s found, how is it made official?

Tracy and his team provided genetic and physical evidence that the Dixie Valley toad constituted a new species. Publication in a stringently peer-reviewed journal verifies such discoveries (Tracy said getting the publication accepted took more than a year and three submissions).

A specimen of the new species is stored at a museum. One sample is stored at California Academy of Science Herpetology Collection and another at UNR.

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