Different species of fruit flies exhibit different markings on their wings.  Researchers have uncovered a genetic mechanism that can explain how such diverse decorations can evolve.

Sean B. Carroll of Howard Hughes Medical Institute and colleagues have studied segments of DNA called cis-regulatory elements, which - unlike genes - do not code for a specific protein.  However, these elements can alter the function of a nearby gene.

In terms of evolution, Carroll argues that mutations in a gene could be very damaging to an organism, whereas a mutation in a cis-regulatory element might cause more subtle changes - like an extra spot on a wing. 

"These systems already have all the structural details in place, like the structure of a Christmas tree," Carroll said. "And all evolution has to do is to alter these regulatory elements mutationally to bring out a pattern -- like hanging ornaments on the tree."

To test this theory, Carroll's team investigated the fruit fly gene, yellow, which was known to affect wing pigmentation.  Both spotted and unspotted flies have this gene, but the scientists discovered that the spotted species had multiple mutations in a nearby cis-regulatory region, which apparently allowed other proteins to interact with the yellow gene.

These interacting proteins resulted in the formation of a separate spot pattern - a "Christmas ornament" from the above analogy.

The study was published in the Feb. 3, 2005, issue of the journal Nature.

-- LiveScience Staff

Credit: Nicolas Gompel and Benjamin Prud'homme