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How Time Flies
10 January 2012

How Time Flies

Flies can tell the time. In fact, some species have two body clocks so they know the time of year and day. For decades, scientists have been arguing over whether there is a connection between nature’s two timepieces, the circadian clock that controls daily activity such as sleeping and feeding, and the seasonal clock that is responsible for hibernation, or its insect equivalent, the diapause. Now, researchers have found a link by cross-breeding two varieties of fruit fly. Both have circadian clocks, but only one has a seasonal clock. The resulting hybrids inherit some genes that appear to be common to both clocks. The discovery is illustrated by this image showing two pairs of ovaries from dissected flies, the top pair functioning normally and the bottom pair, from a hybrid fly, shrivelled and rendered infertile by the onset of the diapause.

Written by Mick Warwicker

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BPoD stands for Biomedical Picture of the Day. Managed by the MRC Laboratory of Medical Sciences until Jul 2023, it is now run independently by a dedicated team of scientists and writers. The website aims to engage everyone, young and old, in the wonders of biology, and its influence on medicine. The ever-growing archive of more than 4000 research images documents over a decade of progress. Explore the collection and see what you discover. Images are kindly provided for inclusion on this website through the generosity of scientists across the globe.

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