"Junk" DNA Has Evolutionary Value

So-called "junk DNA" actually has evolutionary importance, says a University of California, San Diego, study in the Oct. 20 issue of Nature. This form of DNA was tagged with this label because it doesn't contain instructions for protein-coding genes, and also appears to have little or no function that's critically important to evolutionary survival. However, this study of genes from the fruit fly species Drosophila melanogaster found these non-coding regions of junk DNA actually play a vital role in maintaining an organism's genetic integrity. These regions are strongly affected by evolutionary natural selection, which favors the survival of organisms and genes best suited to their particular environment, the study found. Junk DNA accounts for about 80 percent of the total Drosophila genome, the researchers said. The study also revealed that there's an unusually large amount of functional genetic divergence between junk DNA found in different species of Drosophila. The study authors said this provides further proof that junk DNA plays an important role in evolution.