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How monarch butterflies fix bearing in long flight?
2008/1/9 11:44:43
U.S. scientists have discovered that monarch butterflies' biological clocks help them use the sun as a compass, which helps explain how the butterflies find their way from Canada to winter nesting grounds in the mountains of Mexico, according to media reports Wednesday.

Since its discovery, the annual migration of eastern North American monarch butterfly has captivated the scientists. That millions of butterflies annually fly up to about 3,240 km to reach a cluster of pine groves in central Mexico comprising just some 183 square km is for many an awesome and mysterious occurrence.

However, over the past decade, scientists have begun to unveil the journey for what it is -- a spectacular result of biology, driven by an intricate molecular mechanism in a tiny cluster of cells in the butterfly brain.

Monarch butterflies have unique circadian clocks, which regulate daily activities, said Dr. Steven Reppert, the University of Massachusetts neurobiologist who led the research team.

His studies have shown that time compensation is provided by the butterfly's circadian clock, which allows the monarch butterflies to continually correct its flight direction to maintain a fixed flight bearing even as the sun moves across the sky.

The researchers genetically mapped the molecular underpinings of the butterflies' circadian clocks and found cryptochrome proteins common in both insects and mammals. These proteins enable the butterflies to navigate using the sun's position, Reppert said

This clock-to-compass pathway provides an essential link between the clock and the sun compass, as both are necessary for successful orientation and navigation during migration, as Reppert explained.

The find might help shed light on the biological clocks of humans, and in turn aid research into everything from sleep disorders to depression.

Source: Xinhua/agencies

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