Editor's Summary
20 October 2005
The sound of silent DNA
Time to junk the term 'junk DNA', or to reserve it for DNA of proven uselessness. Geneticists favour the less judgmental term 'non-coding DNA' for those parts of the genome not translated into protein, and there is growing evidence that it is important in disease, development and evolution. Despite this, little is known about the evolutionary forces acting on it. Now a new population genetics approach shows that most non-coding DNA in Drosophila melanogaster is subject to adaptive evolution and selection. The big surprise comes from a comparison between Drosophila species: a significant fraction of the divergence between species in non-coding DNA is adaptive, driven by positive selection. In fact, the number of beneficial substitutions in non-coding DNA is an order of magnitude larger than in proteins. Non-coding DNA includes 'cis-acting' regulatory sequences, so this finding may reflect the immense importance of regulatory evolution, previously suggested on intuitive grounds.
News and Views: Evolutionary biology: Fruitfly genome is not junk
A comparison of two fruitfly genomes shows that much of their non-coding DNA is controlled by either negative or positive selection, dealing a double blow to the neutral theory of molecular evolution.
Alexey S. Kondrashov
doi: 10.1038/4371106a
Letter: Adaptive evolution of non-coding DNA in Drosophila
Peter Andolfatto
doi: 10.1038/nature04107
First paragraph | Full Text | PDF (201K) | Supplementary information
