Frogs are teaching scientists how nature can rebound

In 2012, Corinne Richards-Zawacki ventured to her old field sites in the Panama rainforest in search of an elusive target: the variable harlequin frog, which had gone missing in the five years since she last visited.

It had been years since anyone reported seeing the species, and scientists were weighing whether to declare it extinct. But Richards-Zawacki and colleagues weren’t convinced.

“We thought they deserved a second chance,” said Richards-Zawacki, a biology professor in the Kenneth P. Dietrich School of Arts and Sciences.

She was right.

On that first trip, the team found a single frog. Later, they saw signs of more, both the bright yellow object of her search and other species that scientists suspected had disappeared for good. It was a welcome surprise after years of witnessing amphibian declines.

Since then, scientists like Richards-Zawacki have continued to see signs of recovery in some frog and toad populations across the world that decades ago were devastated by the fungal disease chytridiomycosis (chytrid, for short).

“We had been used to the gloom and doom,” she said.

To study the rebound, Richards-Zawacki and a group of colleagues across the U.S. launched an institute today backed by a $12.5 million National Science Foundation grant. Centered at Pitt’s Pymatuning Laboratory of Ecology, RIBBiTR (Resilience Institute Bridging Biological Training and Research) will also look to draw bigger conclusions about how nature bounces back after being disturbed by human activity.

It’s a critical time for a group like this to come together, Richards-Zawacki said: Between climate change, habitat destruction and diseases such as chytrid that are caused by humans moving animals from place to place, nature is under more combined stresses than ever before.

“If we don’t understand how things bounce back, then we won’t know when we’ve hit a tipping point,” she explained. By then, it will be too late to restore those ecosystems to the way they were, or even to an altered state where they can still provide the natural resources that we need.

The first step, though, is simply figuring out what’s out there.

Researchers at the Pymatuning Laboratory of Ecology, a Pitt research lab and field station located in northwestern Pennsylvania and led by Richards-Zawacki, will pioneer modern approaches to tracking amphibians, like collecting tiny traces of DNA from the environment and automatically picking up the sound of frog calls. The latter project will be led by Pitt Assistant Professor of Biological Sciences Justin Kitzes, an expert in acoustic monitoring.

“We have a variety of very high-quality lab facilities that are right there in the middle of the ecosystems where people want to work,” Richards-Zawacki said, adding that nestled in a mosaic of farms, fields, lakes, forests and towns, Pymatuning is the perfect place to test these new technologies.

Work will happen on the Pittsburgh campus, too, dovetailing with a recent effort in Pitt’s Department of Biological Sciences to merge introductory biology labs with research experiences that get students working on real-world scientific problems. Students’ tasks will include analyzing what’s in the skin slime of frogs and toads — “the good stuff,” as Richards-Zawacki calls it — to help figure out what protects the animals from disease.

Graduate researchers will also have the chance to participate in workshops with others who are part of the collaboration, including experts in immunology, microbiomes and mathematical modeling.

Meanwhile, those researchers will conduct carefully aligned parallel experiments at field sites in Pennsylvania, California, Brazil and Panama to see how frogs and toads are rebounding in each location and build a more comprehensive understanding of the different paths recovery can take.

That coordinated effort is a big part of why the National Science Foundation categorizes the effort as an “institute” rather than a more modest grant-funded project, Richards-Zawacki said. “Institutes are there to support teams that are big enough to be able to tackle the big questions in science,” she said. “By coming together as a big team, we can achieve more.”

For Richards-Zawacki, the focus on nature’s resilience represents a vital change — both in a field of science often dominated by bad news and in her own career.

“When it was all about decline and disease and extinction, it was really hard for me to stay motivated,” she said. “I actually took a break from studying amphibian disease for a while. The thing that got me back in the field was wondering whether things could be starting to recover.”

That curiosity was a first step toward asking bigger questions about how ecosystems rebound after human harm. Like her golden frog in the rainforest, it may be too early to write off nature.

— Patrick Monahan