Featured Research

from universities, journals, and other organizations

Robotic Lizards Help Prove Long-standing Signaling Theory

Date:
November 25, 2008
Source:
University of California - Davis
Summary:
Like teachers who rap a ruler before announcing homework in noisy classrooms, Puerto Rican anole lizards perform eye-catching pushups before beginning head-bobbing displays that advertise their territory and status, according to a new study. The study is the first to show that animals in noisy environments can use visual displays to grab their neighbors' attention before initiating a more information-rich performance.

A real anole male has moved from his perch several meters away to confront a robotic rival.
Credit: Terry Ord/UC Davis photography

UC Davis researchers using robotic lizards in a Puerto Rico forest have shown that in noisy visual environments, animals can use body language to alert neighbors to forthcoming information-rich messages.

Like teachers who rap a ruler before announcing homework in noisy classrooms, Puerto Rican anole lizards perform eye-catching pushups before beginning head-bobbing displays that advertise their territory and status, according to a new study by researchers at the University of California, Davis.

With the help of robotic lizards that mimic their flesh-and-blood counterparts, research associate Terry Ord and professor emerita Judy Stamps, both with the Department of Evolution and Ecology, have shown for the first time that animals in noisy environments can use visual displays to grab their neighbors' attention before initiating a more information-rich performance.

The study will be published in the November 24 Proceedings of the National Academy of Sciences.

"What's really interesting is that the anoles are in some way assessing the environmental variables that are likely to affect the detection of their signals," Ord said, "and they are tailoring their behavior accordingly."

The work confirms a nearly 30-year-old hypothesis that when the environment is noisy, animals might use conspicuous signals, or "alerts," to let neighbors know that a message is forthcoming.

Audible alerts, like trills or barks, have been documented in only one species, towhees, but studies suggest that coyotes and tree frogs also issue them. Until now, however, no one has shown that mute species can use body language to do the same thing, said Ord, who also holds a postdoctoral fellowship at Harvard University's Museum of Comparative Zoology.

"It's a real formidable task for animals to be communicating out in the real world," Ord explained. "Not only is there a lot of acoustic noise, but there's visual noise, as well. The trouble for an animal that tries to send an information-rich signal under low-light conditions or when the wind is blowing branches and leaves around is that the signal will not transmit very far. To solve that conundrum, the theory goes, you start the communication with a conspicuous component to attract the attention of your receivers."

Scientists working with audible alerts have the advantage of being able to use recorded songs and calls in the field. But to study body language in yellow-chinned anoles (Anolis gundlachi) living in Puerto Rico's deep, shaded forests, Ord had to design and build realistic models that could dip, bend and unfurl flaps of skin on their chins, known as dewlaps. His hand-painted latex constructions were so realistic they fooled humans and anoles alike.

Ord housed small motors powered by packs of AA batteries in a box below his robotic lizards, then programmed the models to precisely imitate the typical four-legged pushups and head-bobbing displays performed by anoles. He also programmed two alternate sequences: displays with head bobs only (no pushups), and displays that began with quick dewlap extensions, a behavior not typically performed by this species.

Then the researcher planted his creations in a Puerto Rican forest and observed how neighboring anoles responded to the various displays. After viewing and analyzing more than 300 responses, Ord and Stamps concluded that pushups are an alert that the lizards mostly use only when necessary, such as when their neighbors are far away or when the light is dim.

They also found that both the pushups and rapid dewlap extensions prompted neighboring lizards to orient themselves more quickly to the displaying robots than when head bobs were performed without these alerts. The fact that the lizards responded to the atypical, but eye-catching dewlap extensions confirmed the hypothesis that any high-speed movement at the onset of a display could function as an effective alert.

By adding animals that use visual alerts to the roster of species already suspected of using audible alerts, the case can be made that alert signals represent a significant example of evolutionary convergence, Ord noted.

"This is interesting," he said, "because it's an example of very different species converging on a similar strategy."


Story Source:

The above story is based on materials provided by University of California - Davis. Note: Materials may be edited for content and length.


Cite This Page:

University of California - Davis. "Robotic Lizards Help Prove Long-standing Signaling Theory." ScienceDaily. ScienceDaily, 25 November 2008. <www.sciencedaily.com/releases/2008/11/081124174849.htm>.
University of California - Davis. (2008, November 25). Robotic Lizards Help Prove Long-standing Signaling Theory. ScienceDaily. Retrieved September 22, 2014 from www.sciencedaily.com/releases/2008/11/081124174849.htm
University of California - Davis. "Robotic Lizards Help Prove Long-standing Signaling Theory." ScienceDaily. www.sciencedaily.com/releases/2008/11/081124174849.htm (accessed September 22, 2014).

Share This



More Plants & Animals News

Monday, September 22, 2014

Featured Research

from universities, journals, and other organizations


Featured Videos

from AP, Reuters, AFP, and other news services

Raw: San Diego Zoo Welcomes Cheetah Cubs

Raw: San Diego Zoo Welcomes Cheetah Cubs

AP (Sep. 20, 2014) The San Diego Zoo has welcomed two Cheetah cubs to its Safari Park. The nearly three-week-old female cubs are being hand fed and are receiving around the clock care. (Sept. 20) Video provided by AP
Powered by NewsLook.com
Chocolate Museum Opens in Brussels

Chocolate Museum Opens in Brussels

AFP (Sep. 19, 2014) Considered a "national heritage" in Belgium, chocolate now has a new museum in Brussels. In a former chocolate factory, visitors to the permanent exhibition spaces, workshops and tastings can discover derivatives of the cocoa bean. Duration: 01:00 Video provided by AFP
Powered by NewsLook.com
Could Grief Affect The Immune Systems Of Senior Citizens?

Could Grief Affect The Immune Systems Of Senior Citizens?

Newsy (Sep. 19, 2014) The study found elderly people are much more likely to become susceptible to infection than younger adults going though a similar situation. Video provided by Newsy
Powered by NewsLook.com
Jury Delivers Verdict in Salmonella Trial

Jury Delivers Verdict in Salmonella Trial

AP (Sep. 19, 2014) A federal jury has convicted three people in connection with an outbreak of salmonella poisoning five years ago that sickened hundreds of people and was linked to a number of deaths. (Sept. 19) Video provided by AP
Powered by NewsLook.com

Search ScienceDaily

Number of stories in archives: 140,361

Find with keyword(s):
Enter a keyword or phrase to search ScienceDaily for related topics and research stories.

Save/Print:
Share:

Breaking News:
from the past week

In Other News

... from NewsDaily.com

Science News

Health News

Environment News

Technology News



Save/Print:
Share:

Free Subscriptions


Get the latest science news with ScienceDaily's free email newsletters, updated daily and weekly. Or view hourly updated newsfeeds in your RSS reader:

Get Social & Mobile


Keep up to date with the latest news from ScienceDaily via social networks and mobile apps:

Have Feedback?


Tell us what you think of ScienceDaily -- we welcome both positive and negative comments. Have any problems using the site? Questions?
Mobile: iPhone Android Web
Follow: Facebook Twitter Google+
Subscribe: RSS Feeds Email Newsletters
Latest Headlines Health & Medicine Mind & Brain Space & Time Matter & Energy Computers & Math Plants & Animals Earth & Climate Fossils & Ruins