Each fall millions of monarch butterflies from across the eastern United States begin a southward migration in order to escape the frigid temperatures of their northern boundaries, traveling up to 2,000 miles to an overwintering site in a specific grove of fir trees in central Mexico.
Surprisingly, a new study by scientists at the University of Massachusetts Medical School published in Current Biology, suggests that exposure to coldness found in the microenvironment of the monarch's overwintering site triggers their return north every spring. Without this cold exposure, the monarch butterfly would continue flying south.
These findings help explain why monarch butterflies transverse such long distances to overwinter at a relatively small region roughly 300 square miles in size atop frost-covered mountains. Upon arrival in November, the monarchs begin to congregate in tightly packed clusters in a few isolated locations in the high altitude coniferous forests. Both the clustering and the forest cover provide a microenvironment that protects against environmental extremes – the temperature remains low enough to keep metabolic demands low but not cold enough to cause freezing – and ultimately triggers their return north in the spring.
It also suggests that these delicate creatures may be influenced by and vulnerable to global climate changes, say researchers. "The temperature of the microenvironment at the overwintering sites is a critical component for the completion of the migration cycle," said Steven M. Reppert, MD, professor of neurobiology and senior author of the study. "Without this thermal stimulus, the annual migration cycle would be broken, and we could have lost one of the most intriguing biological phenomena in the world."
Though accomplished in a single calendar year, it takes at least three generations of monarch butterflies to complete a single migratory journey. The monarchs that return to Mexico each year have never been to the overwintering sites before, and have no relatives to follow on their way. The biological and genetic mechanisms underlying their incredible journey have intrigued scientists for generations.
Earlier work by Reppert's group found that monarchs rely on a time-compensated sun compass to direct their navigation south. Their new research shows that those same systems are responsible for guiding them north each spring.
This alone, however, didn't explain what was triggering the change in direction each spring. To find out, Patrick Guerra, a postdoctoral fellow in Reppert's lab at UMass Medical School and first author on the Current Biology study, collected wild monarchs at the start of their migration in the fall and subjected the monarchs to the same temperature and light levels they would experience in their overwintering ground in Mexico. When the monarchs were studied in a flight simulator 24 days later, instead of resuming their southward journey, the butterflies headed north.
Further study confirmed that changes in temperature alone altered the flight direction of the monarch butterflies. Those subjected to cold oriented north; monarchs who were protected from the cold would continue to orient south.
These findings, coupled with newly available genetic and genomic tools for monarchs, will lead to new insights about the biological processes underlying their remarkable migratory journey.
"The more we learn, the clearer it becomes that the monarch migration is a uniquely fragile biological process," said Reppert. "Understanding how it works means we'll be better able to protect this iconic system from external threats such as global warming."
About the University of Massachusetts Medical School
The University of Massachusetts Medical School, one of the fastest growing academic health centers in the country, has built a reputation as a world-class research institution, consistently producing noteworthy advances in clinical and basic research. The Medical School attracts more than $250 million in research funding annually, 80 percent of which comes from federal funding sources. The mission of the Medical School is to advance the health and well-being of the people of the commonwealth and the world through pioneering education, research, public service and health care delivery with its clinical partner, UMass Memorial Health Care. For more information, visit www.umassmed.edu.
Jim Fessenden | EurekAlert!
Don't Give the Slightest Chance to Toxic Elements in Medicinal Products
23.03.2018 | Physikalisch-Technische Bundesanstalt (PTB)
North and South Cooperation to Combat Tuberculosis
22.03.2018 | Universität Zürich
Satellites in near-Earth orbit are at risk due to the steady increase in space debris. But their mission in the areas of telecommunications, navigation or weather forecasts is essential for society. Fraunhofer FHR therefore develops radar-based systems which allow the detection, tracking and cataloging of even the smallest particles of debris. Satellite operators who have access to our data are in a better position to plan evasive maneuvers and prevent destructive collisions. From April, 25-29 2018, Fraunhofer FHR and its partners will exhibit the complementary radar systems TIRA and GESTRA as well as the latest radar techniques for space observation across three stands at the ILA Berlin.
The "traffic situation" in space is very tense: the Earth is currently being orbited not only by countless satellites but also by a large volume of space...
An international team of researchers has discovered a new anti-cancer protein. The protein, called LHPP, prevents the uncontrolled proliferation of cancer cells in the liver. The researchers led by Prof. Michael N. Hall from the Biozentrum, University of Basel, report in “Nature” that LHPP can also serve as a biomarker for the diagnosis and prognosis of liver cancer.
The incidence of liver cancer, also known as hepatocellular carcinoma, is steadily increasing. In the last twenty years, the number of cases has almost doubled...
In just a few weeks from now, the Chinese space station Tiangong-1 will re-enter the Earth's atmosphere where it will to a large extent burn up. It is possible that some debris will reach the Earth's surface. Tiangong-1 is orbiting the Earth uncontrolled at a speed of approx. 29,000 km/h.Currently the prognosis relating to the time of impact currently lies within a window of several days. The scientists at Fraunhofer FHR have already been monitoring Tiangong-1 for a number of weeks with their TIRA system, one of the most powerful space observation radars in the world, with a view to supporting the German Space Situational Awareness Center and the ESA with their re-entry forecasts.
Following the loss of radio contact with Tiangong-1 in 2016 and due to the low orbital height, it is now inevitable that the Chinese space station will...
Fraunhofer Institute for Organic Electronics, Electron Beam and Plasma Technology FEP, provider of research and development services for OLED lighting solutions, announces the founding of the “OLED Licht Forum” and presents latest OLED design and lighting solutions during light+building, from March 18th – 23rd, 2018 in Frankfurt a.M./Germany, at booth no. F91 in Hall 4.0.
They are united in their passion for OLED (organic light emitting diodes) lighting with all of its unique facets and application possibilities. Thus experts in...
A new scenario seeking to explain how Mars' putative oceans came and went over the last 4 billion years implies that the oceans formed several hundred million...
23.03.2018 | Event News
19.03.2018 | Event News
16.03.2018 | Event News
23.03.2018 | Materials Sciences
23.03.2018 | Agricultural and Forestry Science
23.03.2018 | Physics and Astronomy