Student and Faculty Member's Study of Rare Frog Behavior Is Cover of National Journal

Rebecca Taylor '16 (left) and Lisa Mangiamele, assistant professor of biological sciences, in the lab at Smith.

As if graduating wasn’t exciting enough, Smith senior Rebecca Taylor recently learned that a study she wrote with a faculty member has been published in the official journal of the National Academy of Sciences.

Their study of the role testosterone plays in the behavior of rare Bornean rock frogs—which Taylor co-authored with Lisa Mangiamele, assistant professor of biological sciences—is the cover of the May 17 issue of Proceedings of the National Academy of Sciences

The research focuses on a unique mating signal, called a foot flag, that a tropical frog species has developed over millions of years in response to its rainforest waterfall habitat. Instead of croaking sounds used by most frogs—which would be difficult to hear near the rushing water—male Bornean rock frogs wave their back legs to expose white foot webbing as a signal to potential mates.

The new study, done in collaboration with researchers at Wake Forest University and the University of Vienna, Austria, found that testosterone plays an important role in the development of the frogs’ unique behavior.

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A tiny male Bornean rock frog shows its unique foot-flagging signal to potential mates.

“We know that testosterone increases male communication signals,” Mangiamele says. “So the big question we were asking in our paper is, when we see a novel signal emerge—such as the one these rock frogs use—is it also modulated by testosterone?”

Research that Taylor did for the study helped reveal the answer is “yes,” Mangiamele says. Taylor watched video of rock frogs living in an indoor rainforest enclosure at the Vienna Zoo in Austria and counted the number of times males waved their back legs to signal females. She then performed a statistical analysis to test whether frogs treated with testosterone waved more than untreated frogs.

“Rebecca’s statistical analysis is what helped us realize we were onto something,” Mangiamele says. “Our study shows that this novel foot-flagging behavior is indeed increased by testosterone.”

In fact, the data showed the rock frog’s leg muscles are about 10 times more sensitive to testosterone than those of a related frog species that doesn’t use foot flagging—a finding that has implications for understanding the evolution of animal behavior.

“We know this is a novel signal and a relatively new one among amphibians in the tropics,” Mangiamele says. “Because foot flagging makes communication among these animals more efficient in their noisy environment, our study shows evolution works on behavior and on the leg muscles of the frogs.”

Taylor says watching more than 100 hours of video wasn’t the most difficult part of the research—though she concedes “there was a lot of rewinding” before she became expert at spotting frog foot-waving.

The biggest challenge was mastering statistical models used to analyze the foot flagging counts. “I had to figure out how to calculate things differently, in ways that weren’t covered in my basic statistics class,” Taylor says.

A neuroscience and biochemistry major at Smith, Taylor says having research published in a peer-reviewed journal has helped bolster her identity as a scientist.

“That’s not something I expected to happen,” she says. “It has definitely boosted my confidence in my skills as a researcher.”

Mangiamele says Taylor exhibited one of the key requirements for success in STEM.

“It was her passion that made the difference,” Mangiamele says. “She was invested in the outcome of our study and really wanted to find the answer.”

The new study suggests avenues for continued research on the tiny rainforest frogs, Mangiamele says.

“Now that we know the foot-flagging behavior is increased by testosterone, we can look further at the physiological basis for these signals,” she says. “The next step is to look at the spinal cords of these animals. This is an ongoing project for our lab.”

Taylor says she will use lessons learned through her work on the frog study when she begins work as a research assistant at Beth Israel Deaconess Medical Center in Boston after graduation.

“I’ve learned I have the patience to find answers to questions I’m excited about,” she says.