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!
Closing the carbon loop
08.12.2016 | University of Pittsburgh
Newly discovered bacteria-binding protein in the intestine
08.12.2016 | University of Gothenburg
In recent years, lasers with ultrashort pulses (USP) down to the femtosecond range have become established on an industrial scale. They could advance some applications with the much-lauded “cold ablation” – if that meant they would then achieve more throughput. A new generation of process engineering that will address this issue in particular will be discussed at the “4th UKP Workshop – Ultrafast Laser Technology” in April 2017.
Even back in the 1990s, scientists were comparing materials processing with nanosecond, picosecond and femtosesecond pulses. The result was surprising:...
Have you ever wondered how you see the world? Vision is about photons of light, which are packets of energy, interacting with the atoms or molecules in what...
A multi-institutional research collaboration has created a novel approach for fabricating three-dimensional micro-optics through the shape-defined formation of porous silicon (PSi), with broad impacts in integrated optoelectronics, imaging, and photovoltaics.
Working with colleagues at Stanford and The Dow Chemical Company, researchers at the University of Illinois at Urbana-Champaign fabricated 3-D birefringent...
In experiments with magnetic atoms conducted at extremely low temperatures, scientists have demonstrated a unique phase of matter: The atoms form a new type of quantum liquid or quantum droplet state. These so called quantum droplets may preserve their form in absence of external confinement because of quantum effects. The joint team of experimental physicists from Innsbruck and theoretical physicists from Hannover report on their findings in the journal Physical Review X.
“Our Quantum droplets are in the gas phase but they still drop like a rock,” explains experimental physicist Francesca Ferlaino when talking about the...
The Max Planck Institute for Physics (MPP) is opening up a new research field. A workshop from November 21 - 22, 2016 will mark the start of activities for an innovative axion experiment. Axions are still only purely hypothetical particles. Their detection could solve two fundamental problems in particle physics: What dark matter consists of and why it has not yet been possible to directly observe a CP violation for the strong interaction.
The “MADMAX” project is the MPP’s commitment to axion research. Axions are so far only a theoretical prediction and are difficult to detect: on the one hand,...
16.11.2016 | Event News
01.11.2016 | Event News
14.10.2016 | Event News
08.12.2016 | Life Sciences
08.12.2016 | Physics and Astronomy
08.12.2016 | Materials Sciences