Robot Reptile “Released” Into Wild to Aid Breeding Research
Posted by Miqe on June 12, 2007
On Stephens Island in New Zealand’s storm-wracked Cook Strait, the tuatara—one of the most ancient reptile species on Earth—is getting a hand from distinctly 21st-century science (see a New Zealand map).Researchers have placed in the wild a very special male that, like its wild cousins, can put on physical displays to establish its dominance.
But this reptile’s skin is made of rubber, not scales, and its “heart” is a nickel-cadmium battery.
The alpha male in question is “Robo-Ollie,” a robotic tuatara created to help researchers understand the behavior of these rare reptiles, the last species in a family that dates back 200 million years.
Specifically, postdoctoral student Jennifer Moore wants to know how male tuatara establish dominance—how they attract and keep females.
Understanding critical behaviors could help tuatara translocation and captive-breeding programs, perhaps by guiding conservation managers to the genetically fittest, most productive males.
(Related news: “Warming May Drive Gender-Bending Reptiles Extinct, Scientists Say” [November 10, 2006].)
“We needed a model we could manipulate in the field to look at aggression between males, which ultimately leads to reproductive success,” Moore said.
“That can give us an idea of who is winning the fights; who’s getting the ladies, who’s fathering the children—who is more successful, generally.”
To Bob or Not to Bob
To create a controllable tuatara, Moore enlisted aid from Weta Workshops, the Wellington-based animatronics company that fashioned monsters for such films as Peter Jackson’s Lord of the Rings trilogy.
Weta’s senior prosthetics supervisor, Gino Acevedo, first took a cast from the venerable corpse of Oliver, a captive tuatara that recently passed away at Victoria University in Wellington.
“After defrosting him, I packed his body with cotton wool, then added in spheres for his eyes and pins to hold up his spines,” Acevedo said.
With advice from Moore, he set Oliver’s body into a lifelike pose before pouring silicone over him to create a perfect negative mold.
From this Acevedo made a polyurethane cast out of the mold.
Weta then installed electrical servos, tiny devices for controlling motion that allow Moore to choreograph Robo-Ollie’s territorial posturing. The robot can’t walk around; its movement is limited to its head, Moore noted.
And there are still a few tweaks to be made to his programming: Right now Robo-Ollie inadvertently displays at least one gender-bending trait.
“He bobs his head,” Moore said, “which we now know is a female signal, so he’s sending mixed messages. We’re going to have to tweak things a little bit.”
Moore thinks head bobbing in females is an appeasement gesture, a way of pacifying aggressive males.
Instead, “Ollie should be gaping his mouth, which is a very strong signal from one male to another.”
Ritual of Aggression
Moore and her team spent five weeks with Robo-Ollie on Stephens Island in March gaining valuable insights into the tuatara breeding hierarchy.
After the robot is placed in the wild, the researchers left it alone for a few hours at a time, with only remote cameras to monitor interactions.
After reviewing the tapes, Moore and her colleagues have seen wild tuatara respond less with aggression and more with curiosity.
Robo-Ollie has taught the researchers that gaping among males is just the curtain-raiser in a long, ritualized pantomime.
“If one gapes and the other one doesn’t gape back, that’s the end of it,” Moore said.
“But if one gapes and the other one gapes back, then the first one puffs up and then the other one puffs up, and it escalates from there.
“If one doesn’t back down, it degenerates into full-on fighting and rolling.”
Moore thinks tuatara have evolved such rites as a way of stalling physical confrontation.
“These are animals that spend perhaps 95 percent of their time sitting motionless. So if they are forced to do something that requires big bursts of energy, then that’s really costly,” she said.
“They often lose tails in fights, and [regenerating them] can be a big cost, too.”
Eventually, Moore said, she believes her data will show a correlation between competitive success and reproductive success.
For example, it appears that just 25 percent of the males produce all of Stephen Island’s young. Typically, these are the biggest individuals, some of which could be up to 90 years old.
But much remains unexplained.
For example, researchers right now believe that tuatara are highly visual creatures and don’t rely on scent for establishing territory or breeding.
But Moore noted, scientists don’t understand olfaction in tuatara very well, so there’s a chance that smell could play a role.
The researcher also noted that the reptiles don’t always practice expected patterns of fidelity.
“Male tuatara may have one or two partners in a season,” she said. “On the other side of the coin, females will occasionally mate with more than one male in a season, so there’s a lot going on.
“It’s complex. I’m just starting to get some of these details figured out.”
From National Geographic