Forum for Science, Industry and Business

Sponsored by:     3M 
Search our Site:

 

Body clocks keep migrating monarchs on course, Science study shows

23.05.2003


Butterfly flight simulator sheds light on epic migration



During their winter migration to Mexico, monarch butterflies depend on an internal clock to help them navigate in relation to the sun, scientists have found.

By studying monarchs inside a specially designed flight simulator, the researchers have gathered what they believe is the first direct evidence of the essential role of the circadian clock in celestial navigation. The study appears in the journal Science, published by the American Association for the Advancement of Science (AAAS).


In the fall, monarch butterflies journey from central and eastern North America to a small region in central Mexico. Only every fourth or fifth generation makes the trip, indicating that the urge to migrate is instinctive, rather than learned.

"Monarchs have a genetic program to undergo this marvelous long term flight in the fall…. They are essentially hell-bent on making it to their over-wintering grounds," said Science author Steven Reppert of the University of Massachusetts Medical School.

While scientists are fairly certain that monarchs use the sun to navigate, they know less about how the butterflies adjust their direction each day, as the sun’s position in the sky changes. It has long been suspected that monarchs use their internal, "circadian" clock as part of their sun compass.

"We have shown the requirement of the circadian clock for monarch butterfly migration," said Reppert. "When the clock is disrupted, monarchs are unable to orient toward Mexico. Without proper navigation, their migration to the south wouldn’t occur, and that generation of butterflies would not survive."

Reppert chose monarchs for the study in part because they don’t learn their route, as honeybees foraging for nectar do, for example.

"Monarch butterfly navigation seems to involve the interaction between a clock and a compass. This makes monarch navigation a bit simpler than navigation in foraging insects where each new route has to be learned," Reppert said.

Understanding how the circadian clock assists the sun compass in the relatively simple navigation by monarchs could provide a model for studying navigation by other animals, Reppert said, citing both foragers such as honeybees and desert ants, as well as long distance migrators such as songbirds.

"We would like to know how the circadian clock functions in four dimensions – not only how the clock functions to keep time, but also how time regulates spatial information," he said. "Increasing knowledge of the genetic makeup of the monarch circadian clock will help tease apart the entire migratory process, a process that remains one of the great mysteries of biology."

Research in other animals has been turning up a number of genes that make up the circadian clock, as their expression oscillates in a daily cycle. The clock is "entrained" to the daily light cycle via specialized by special light-sensitive cells, called photoreceptors.

The researchers found that a common clock gene, known as per, is also part of the monarch circadian clock. Constant light disrupted the cycling of this gene’s expression. It also affected the time of day butterflies emerged from their chrysalises, known to be a marker of circadian time-keeping in other insects.

Reppert and his colleagues then studied the effects of manipulating the daily light and dark cycles on monarchs inside a specially designed flight simulator, with a video camera and computer that record the flight direction.

After being housed under a light/dark cycle in the laboratory that was close to the fall outdoor lighting cycle (light from 7:00 a.m. to 7:00 p.m.) migrant butterflies exposed to outdoor sun oriented to the southwest, toward Mexico. Butterflies housed under an earlier cycle (light from 1:00 a.m. to 1:00 p.m.) flew to the southeast.

When the butterflies were exposed to constant light, they flew directly toward the sun, presumably having lost their sense of time.

Reppert’s team also found that, while UV light is required for sun compass navigation, some other wavelength of light was required for entraining the butterflies’ clocks. This difference may provide a means for untangling the two biological processes.

"The light input pathways are quite distinct, so tracking those pathways in may eventually lead us to the cellular level where this clock-compass interaction is occurring," Reppert said.

Lisa Onaga | EurekAlert!
Further information:
http://www.aaas.org/

More articles from Life Sciences:

nachricht Colorectal cancer: Increased life expectancy thanks to individualised therapies
20.02.2020 | Christian-Albrechts-Universität zu Kiel

nachricht Sweet beaks: What Galapagos finches and marine bacteria have in common
20.02.2020 | Max-Planck-Institut für Marine Mikrobiologie

All articles from Life Sciences >>>

The most recent press releases about innovation >>>

Die letzten 5 Focus-News des innovations-reports im Überblick:

Im Focus: A step towards controlling spin-dependent petahertz electronics by material defects

The operational speed of semiconductors in various electronic and optoelectronic devices is limited to several gigahertz (a billion oscillations per second). This constrains the upper limit of the operational speed of computing. Now researchers from the Max Planck Institute for the Structure and Dynamics of Matter in Hamburg, Germany, and the Indian Institute of Technology in Bombay have explained how these processes can be sped up through the use of light waves and defected solid materials.

Light waves perform several hundred trillion oscillations per second. Hence, it is natural to envision employing light oscillations to drive the electronic...

Im Focus: Freiburg researcher investigate the origins of surface texture

Most natural and artificial surfaces are rough: metals and even glasses that appear smooth to the naked eye can look like jagged mountain ranges under the microscope. There is currently no uniform theory about the origin of this roughness despite it being observed on all scales, from the atomic to the tectonic. Scientists suspect that the rough surface is formed by irreversible plastic deformation that occurs in many processes of mechanical machining of components such as milling.

Prof. Dr. Lars Pastewka from the Simulation group at the Department of Microsystems Engineering at the University of Freiburg and his team have simulated such...

Im Focus: Skyrmions like it hot: Spin structures are controllable even at high temperatures

Investigation of the temperature dependence of the skyrmion Hall effect reveals further insights into possible new data storage devices

The joint research project of Johannes Gutenberg University Mainz (JGU) and the Massachusetts Institute of Technology (MIT) that had previously demonstrated...

Im Focus: Making the internet more energy efficient through systemic optimization

Researchers at Chalmers University of Technology, Sweden, recently completed a 5-year research project looking at how to make fibre optic communications systems more energy efficient. Among their proposals are smart, error-correcting data chip circuits, which they refined to be 10 times less energy consumptive. The project has yielded several scientific articles, in publications including Nature Communications.

Streaming films and music, scrolling through social media, and using cloud-based storage services are everyday activities now.

Im Focus: New synthesis methods enhance 3D chemical space for drug discovery

After helping develop a new approach for organic synthesis -- carbon-hydrogen functionalization -- scientists at Emory University are now showing how this approach may apply to drug discovery. Nature Catalysis published their most recent work -- a streamlined process for making a three-dimensional scaffold of keen interest to the pharmaceutical industry.

"Our tools open up whole new chemical space for potential drug targets," says Huw Davies, Emory professor of organic chemistry and senior author of the paper.

All Focus news of the innovation-report >>>

Anzeige

Anzeige

VideoLinks
Industry & Economy
Event News

70th Lindau Nobel Laureate Meeting: Around 70 Laureates set to meet with young scientists from approx. 100 countries

12.02.2020 | Event News

11th Advanced Battery Power Conference, March 24-25, 2020 in Münster/Germany

16.01.2020 | Event News

Laser Colloquium Hydrogen LKH2: fast and reliable fuel cell manufacturing

15.01.2020 | Event News

 
Latest News

Journey to the center of Mars

20.02.2020 | Physics and Astronomy

Laser writing enables practical flat optics and data storage in glass

20.02.2020 | Physics and Astronomy

New graphene-based metasurface capable of independent amplitude and phase control of light

20.02.2020 | Power and Electrical Engineering

VideoLinks
Science & Research
Overview of more VideoLinks >>>