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 Ion treatments for cardiac arrhythmia — Non-invasive alternative to catheter-based surgery
20.01.2017 | GSI Helmholtzzentrum für Schwerionenforschung GmbH

nachricht Seeking structure with metagenome sequences
20.01.2017 | DOE/Joint Genome Institute

All articles from Life Sciences >>>

The most recent press releases about innovation >>>

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

Im Focus: Traffic jam in empty space

New success for Konstanz physicists in studying the quantum vacuum

An important step towards a completely new experimental access to quantum physics has been made at University of Konstanz. The team of scientists headed by...

Im Focus: How gut bacteria can make us ill

HZI researchers decipher infection mechanisms of Yersinia and immune responses of the host

Yersiniae cause severe intestinal infections. Studies using Yersinia pseudotuberculosis as a model organism aim to elucidate the infection mechanisms of these...

Im Focus: Interfacial Superconductivity: Magnetic and superconducting order revealed simultaneously

Researchers from the University of Hamburg in Germany, in collaboration with colleagues from the University of Aarhus in Denmark, have synthesized a new superconducting material by growing a few layers of an antiferromagnetic transition-metal chalcogenide on a bismuth-based topological insulator, both being non-superconducting materials.

While superconductivity and magnetism are generally believed to be mutually exclusive, surprisingly, in this new material, superconducting correlations...

Im Focus: Studying fundamental particles in materials

Laser-driving of semimetals allows creating novel quasiparticle states within condensed matter systems and switching between different states on ultrafast time scales

Studying properties of fundamental particles in condensed matter systems is a promising approach to quantum field theory. Quasiparticles offer the opportunity...

Im Focus: Designing Architecture with Solar Building Envelopes

Among the general public, solar thermal energy is currently associated with dark blue, rectangular collectors on building roofs. Technologies are needed for aesthetically high quality architecture which offer the architect more room for manoeuvre when it comes to low- and plus-energy buildings. With the “ArKol” project, researchers at Fraunhofer ISE together with partners are currently developing two façade collectors for solar thermal energy generation, which permit a high degree of design flexibility: a strip collector for opaque façade sections and a solar thermal blind for transparent sections. The current state of the two developments will be presented at the BAU 2017 trade fair.

As part of the “ArKol – development of architecturally highly integrated façade collectors with heat pipes” project, Fraunhofer ISE together with its partners...

All Focus news of the innovation-report >>>

Anzeige

Anzeige

Event News

Sustainable Water use in Agriculture in Eastern Europe and Central Asia

19.01.2017 | Event News

12V, 48V, high-voltage – trends in E/E automotive architecture

10.01.2017 | Event News

2nd Conference on Non-Textual Information on 10 and 11 May 2017 in Hannover

09.01.2017 | Event News

 
Latest News

An innovative high-performance material: biofibers made from green lacewing silk

20.01.2017 | Materials Sciences

Ion treatments for cardiac arrhythmia — Non-invasive alternative to catheter-based surgery

20.01.2017 | Life Sciences

Bodyguards in the gut have a chemical weapon

20.01.2017 | Life Sciences

VideoLinks
B2B-VideoLinks
More VideoLinks >>>