Monarch Butterfly Migration: The Secret Power of White Spots

by Klaus Müller
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Monarch butterfly migration

Monarch Butterfly Migration: The Influence of White Spots on Successful Flight

Recent research conducted by the University of Georgia reveals that monarch butterflies adorned with more white spots on their wings have a higher likelihood of completing their extensive migration to south and central Mexico.

It turns out that monarch butterflies with larger white spots exhibit enhanced flight efficiency, making their long journeys considerably easier.

In this new study, approximately 400 wild monarch wings were examined, and it was discovered that the monarchs who successfully migrated had about 3% less black pigmentation and 3% more white pigmentation on their wings. The researchers propose that the butterflies’ coloring is linked to the amount of solar radiation they receive during their migration, with the white spots playing a role in improving their flight efficiency. However, due to rising temperatures and alterations in solar radiation, these butterflies may need to adapt in order to maintain their migration success.

For those curious about the origin of the monarch butterfly’s distinctive spots, researchers from the University of Georgia may have found an answer. According to their study, monarch butterflies with a greater number of white spots demonstrate a higher rate of success in reaching their wintering destination over long distances. While the exact mechanism by which the spots aid in the species’ migration remains unclear, it is possible that they influence airflow patterns around their wings.

Lead author Andy Davis, an assistant researcher in UGA’s Odum School of Ecology, explains, “We embarked on this project to understand how such a small creature can accomplish such a successful long-distance flight. Initially, we hypothesized that monarchs with darker wings would be more successful at migrating since dark surfaces can improve flight efficiency. However, our findings contradicted our expectations.”

Surprisingly, it was the monarchs with less black pigmentation on their wings and more white spots that successfully reached their ultimate destination, spanning nearly 3,000 miles to south and central Mexico.

Davis further emphasizes, “It seems that the white spots are the differentiating factor.”

The University of Georgia study demonstrates that monarch butterflies with an abundance of white spots on their wings experience greater success in their long-distance migration, likely due to improved flight efficiency through optimized absorption of solar energy. Nevertheless, this advantage is threatened by climate change, as heightened solar intensity has the potential to reduce aerial efficiency.

Migration serves as a driving force for the development of butterfly spots. Through the analysis of nearly 400 wild monarch wings collected at different stages of their journey, the researchers measured the proportions of different colors. They found that successful migrant monarchs exhibited approximately 3% less black pigmentation and 3% more white pigmentation on their wings.

An additional analysis of museum specimens, encompassing monarchs and six other butterfly species, highlighted the monarchs’ significantly larger white spots compared to their nonmigratory counterparts.

The only other species that came close to displaying a similar proportion of white spots on its wings was the semi-migratory relative of the monarch, known as the southern monarch.

Monarchs utilize solar energy to enhance their flight capabilities. The researchers believe that the butterflies’ coloration is connected to the amount of solar radiation they receive during their journey. Given that the monarchs undertake longer journeys and, consequently, encounter greater sunlight exposure, they have evolved to possess more white spots.

Davis explains, “Monarchs receive an extreme amount of solar energy during their journey, especially since they fly with their wings spread open most of the time. After engaging in this migration for thousands of years, they have figured out a way to utilize that solar energy to enhance their aerial efficiency.”

However, as temperatures continue to rise and alter the amount of solar radiation reaching the Earth’s surface, monarchs will likely need to adapt in order to survive, as pointed out by Mostafa Hassanalian, co-author of the study and an associate professor at the New Mexico Institute of Mining and Technology.

Davis adds, “With increased solar intensity, some of that aerial efficiency could be lost. This would present yet another obstacle hindering the species’ fall migration to Mexico.”

Fortunately, the news is not entirely bleak for these airborne insects. Previous work conducted by Davis indicated that the summer populations of monarchs have remained relatively stable over the past 25 years. This finding suggests that the species’ population growth during the summer compensates for losses incurred during migration, winter conditions, and changing environmental factors.

Davis concludes, “The breeding population of monarchs appears to be fairly stable, so the greatest challenges faced by the monarch population lie in reaching their winter destination. This study allows us to gain further insight into how monarchs successfully arrive at their destination.”

The study, titled “How the monarch got its spots: Long-distance migration selects for larger white spots on monarch butterfly wings,” was published in PLOS ONE. Co-authors of the study include Christina Vu from UGA’s Odum School of Ecology, Paola A. Barriga from UGA’s Department of Plant Biology, and Brenden Herkenhoff from New Mexico Tech.

Frequently Asked Questions (FAQs) about Monarch butterfly migration

What did the researchers from the University of Georgia find regarding monarch butterflies and their migration?

The researchers found that monarch butterflies with more white spots on their wings are more likely to complete their long-distance migration to south and central Mexico. These white spots contribute to improved flight efficiency, making the long trips easier for the butterflies.

How many wild monarch wings were examined in the study?

The study examined nearly 400 wild monarch wings to gather data on their color proportions and analyze the relationship between wing pigmentation and migration success.

How do the white spots on the wings of monarch butterflies help in their migration?

While the exact mechanism is not yet clear, it is believed that the white spots may influence airflow patterns around the wings, contributing to enhanced flight efficiency. Additionally, the white spots may play a role in optimizing solar energy absorption, which is crucial for their long-distance flights.

How does climate change affect the advantage of white spots in monarch butterfly migration?

Climate change poses a threat to the advantage provided by white spots. Rising temperatures and changes in solar radiation can potentially reduce the butterflies’ aerial efficiency, hindering their successful migration to Mexico. The monarch butterflies may need to adapt to these changing conditions to maintain their migration success.

Are the breeding populations of monarch butterflies stable?

Yes, according to previous research, the breeding populations of monarch butterflies have remained relatively stable over the past 25 years. This suggests that the species’ population growth during the summer compensates for losses during migration, winter weather, and other environmental factors. The primary challenges lie in ensuring successful migration to their wintering destination.

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