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 Topologische Quantenchemie
21.07.2017 | Max-Planck-Institut für Chemische Physik fester Stoffe

nachricht Topological Quantum Chemistry
21.07.2017 | Max-Planck-Institut für Chemische Physik fester Stoffe

All articles from Life Sciences >>>

The most recent press releases about innovation >>>

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

Im Focus: Manipulating Electron Spins Without Loss of Information

Physicists have developed a new technique that uses electrical voltages to control the electron spin on a chip. The newly-developed method provides protection from spin decay, meaning that the contained information can be maintained and transmitted over comparatively large distances, as has been demonstrated by a team from the University of Basel’s Department of Physics and the Swiss Nanoscience Institute. The results have been published in Physical Review X.

For several years, researchers have been trying to use the spin of an electron to store and transmit information. The spin of each electron is always coupled...

Im Focus: The proton precisely weighted

What is the mass of a proton? Scientists from Germany and Japan successfully did an important step towards the most exact knowledge of this fundamental constant. By means of precision measurements on a single proton, they could improve the precision by a factor of three and also correct the existing value.

To determine the mass of a single proton still more accurate – a group of physicists led by Klaus Blaum and Sven Sturm of the Max Planck Institute for Nuclear...

Im Focus: On the way to a biological alternative

A bacterial enzyme enables reactions that open up alternatives to key industrial chemical processes

The research team of Prof. Dr. Oliver Einsle at the University of Freiburg's Institute of Biochemistry has long been exploring the functioning of nitrogenase....

Im Focus: The 1 trillion tonne iceberg

Larsen C Ice Shelf rift finally breaks through

A one trillion tonne iceberg - one of the biggest ever recorded -- has calved away from the Larsen C Ice Shelf in Antarctica, after a rift in the ice,...

Im Focus: Laser-cooled ions contribute to better understanding of friction

Physics supports biology: Researchers from PTB have developed a model system to investigate friction phenomena with atomic precision

Friction: what you want from car brakes, otherwise rather a nuisance. In any case, it is useful to know as precisely as possible how friction phenomena arise –...

All Focus news of the innovation-report >>>

Anzeige

Anzeige

Event News

Closing the Sustainability Circle: Protection of Food with Biobased Materials

21.07.2017 | Event News

»We are bringing Additive Manufacturing to SMEs«

19.07.2017 | Event News

The technology with a feel for feelings

12.07.2017 | Event News

 
Latest News

NASA looks to solar eclipse to help understand Earth's energy system

21.07.2017 | Earth Sciences

Stanford researchers develop a new type of soft, growing robot

21.07.2017 | Power and Electrical Engineering

Vortex photons from electrons in circular motion

21.07.2017 | Physics and Astronomy

VideoLinks
B2B-VideoLinks
More VideoLinks >>>