Why some monarch butterflies are marathoners
Why some monarch butterflies are marathoners
Monarch butterflies can be found throughout the world, but only in North America do they make a spectacular mass migration, annually flying from as far north as Canada to winter in Mexico.
Now, by sequencing genomes of 90 monarch butterflies from around the world, researchers have discovered a gene that plays a critical role in determining whether monarchs are migratory, along with new details about their origins, migratory behavior and coloring, reports The New York Times.
Until now, for example, it was thought that North American monarchs were predated by those in South and Central America.
The new research suggests that the North Americans are oldest, said Marcus Kronforst, an evolutionary biologist at the University of Chicago and an author of the study, which appears in Nature.
“And then at some point,” he said, “they dispersed into South and Central America and across the Atlantic and Pacific Oceans.”
The scientists discovered that migratory butterflies had reduced levels of a collagen gene that is involved in forming flight muscles. By using a flight monitor, they also found that the migrators consumed less oxygen and had a lower metabolic rate, allowing them to fly long distances.
“I like to think of it as a marathon runner versus a sprinter,” Dr Kronforst said. “The migratory ones are really marathon runners.”
While most monarchs are orange and black, a small percentage of those in Hawaii are white and black.
“There’s one spot in one gene where all the white ones are different from all the orange ones,” Dr Kronforst said.