Rules of Attraction
There’s something about UT biologist Michael Ryan’s robotic male frogs that seem to make the females turn into horny toads.
Photo courtesy Frog Robot
Since 1982, Ryan has been a research associate at the Smithsonian Tropical Research Institute in Panama, where he has traveled every summer to study animal communication and sexual selection—specifically, the male and female mating behaviors of the túngara frog. By studying this native species of northern South and Central America for such an extended amount of time, Ryan says he and his fellow researchers from around the United States hope to gain a better understanding of how the frogs’ brains place information within their sensory channels.
But this group’s methods of research are not like most. Along with Ryan Taylor, an associate professor of biology at Salisbury University in Maryland, Walt Wilczynski, the director of the Neuroscience Institute at Georgia State University, and David Cannatella, a professor in the Section of Integrative Biology at UT, the biologists address questions about the variation in sexual selection that each male frog’s “chuck,” or ribbit, causes in the female amphibian’s brain. Think of it as trying to explain why some women prefer men with deeper voices.
For their study, the team of researchers began employing a robotic frog (pictured on page 30) seven years ago. Built by University of Wisconsin–La Crosse biologist Barrett Klein and Brooklyn’s Moey design studio co-founder Joey Stein, this mechanical decoy helps with assessing the acoustic and visual signal components when the mates choose each other.
The robotic male frog’s fake vocal sac, which is located underneath the chin, is activated by remote control. The female’s responses are monitored as the male’s calls are adjusted. The scientists have been able to discover how a female has the potential to evolve traits that exploit any pre-existing preferences towards the male’s mating calls. According to Ryan, that’s been the easier part of their work. “The challenge actually came in making the robots,” he says.
For instance, because of the stretchy material, condoms were originally used to make the robots’ expanding vocal sacs. “But they weren’t strong enough,” Ryan laughs. A switch was made last summer to a catheter material that has proven to be more successful during testing.
These remote-controlled characteristics and a realistic coat to duplicate the túngara’s markings seem to work nicely when it comes to turning female frogs’ heads. Now, with the help of six to 12 of these mechanical frogs, Ryan and his colleagues hope to gain further insight into the túngara’s motives and find a better understanding of other species’ mating habits in the future.