Think of a monarch butterfly (帝王蝶), and a unique image pops up: black-and-orange wings, with some white spots around the black edges. Those white spots may actually help monarchs complete their long-distance migration by changing the airflow around their wings. This is the new idea of a team of researchers that has analyzed hundreds of monarch wings collected along their migration routes.
“If you have larger white spots, you’re simply more successful at reaching Mexico,” says Andy Davis, a researcher. He and his colleagues believe that the pattern of color could interact with sunlight to create some temperature differences on the wing that can change airflow, easing the butterflies’ flight.
Monarch butterflies definitely need to fly well to complete their annual fall migration of up to 3,000 miles. Monarchs from as far north as Canada fly south every fall all the way to some mountain top sites in central Mexico. Most research on butterfly coloring focuses on its use as a warning to predators (捕食者). Since monarchs eat milkweed that contains poisons, their bright orange color serves as a signal that they’re unpleasant prey (猎物).
Andy Davis had studied the black-and-white patterns on migrating birds, and concluded that black coloring could affect temperature and airflow in ways that might improve their flight performance. So the researchers decided to look at the black-and-white pattern in the edge of monarch wings. What they found is that the wings of the summer monarchs that aren’t migrating have less white, while those that are migrating but haven’t made it all the way to Mexico have more. And monarchs that successfully reached Mexico have even more white.
“It is a totally new idea,” says Marcus Kronforst, a biologist. “I’ve worked on butterfly color patterns my whole life, but it’s never crossed my mind that it might influence how the butterflies fly. I do think that this aerodynamic (空气动力学) explanation is exciting. It’s definitely different. But I just think there are potentially some other explanations that could be explored.”
【小题1】What is the new idea of monarch butterflies’ white spots?A.They serve as a warning to predators. |
B.They improve butterflies’ flying performance. |
C.They attract the attention of butterfies’ mates. |
D.They help butterflies hide in their surroundings. |
A.By changing the flow of air. |
B.By making butterflieslighter. |
C.By guiding migratingbutterflies. |
D.By turning sunshine into energy. |
A.Unconcerned. | B.Supportive. |
C.Skeptical. | D.Disappointed. |
A.Monarch butterflies migrate the longest distance |
B.Monarch butterflies use airflow to help their flights |
C.Monarch butterflies have more white spots than others |
D.Monarch butterflies’ white spots may help them fly farther |