Scientists have discovered how monarch butterflies are able to complete such an astounding mass migration of 3,000 miles.
According to Reuters, the authors of a study published in the journal Nature sequenced the insect's genome and found one gene that directly affected the efficiency of its flight muscle. The monarch butterfly will migrate from anywhere as far as Canada down to Mexico and parts of coastal California.
"The results of this study shift our whole thinking about these butterflies," study senior author Dr. Marcus Kronforst, an assistant professor of ecology and evolution at the University of Chicago, said in a press release. "Migration is regarded as a complex behavior, but every time that the butterflies have lost migration, they change in exactly the same way, in this one gene involved in flight muscle efficiency.
"In populations that have lost migration, efficiency goes down, suggesting there is a benefit to flying fast and hard when they don't need to migrate."
The study authors suggested that monarch butterflies are long used to this protracted mass migration, meaning they would have developed the muscle capacity to do it and then passed it down from generation to generation.
"One gene really stood out from everything else in the genome," Kronforst told Reuters. "An analogy might be the difference between marathon runners (migrating butterflies) and sprinters."
However, not all monarch butterflies are travelers. Though they are found chiefly in North America, species found elsewhere are non-migratory. The study authors sequenced the genome of 92 monarch butterflies from several different parts of the world and found the specific flight muscle gene just in the migratory ones.
"I find it amazing that these little butterflies live for months and fly thousands of miles to perform this annual migration," Kronforst said. "Our study shows that monarchs have been doing this every year for millions of years. There is nothing else like this on the planet."
