Summary: © 2005 Nature Publishing Group
Adaptive evolution of non-coding DNA in Drosophila
Peter Andolfatto1
A large fraction of eukaryotic genomes consists of DNA that is not
translated into protein sequence, and little is known about its
functional significance. Here I show that several classes of non-
coding DNA in Drosophila are evolving considerably slower than
synonymous sites, and yet show an excess of between-species
divergence relative to polymorphism when compared with
synonymous sites. The former is a hallmark of selective constraint,
but the latter is a signature of adaptive evolution, resembling
general patterns of protein evolution in Drosophila1,2
. I estimate
that about 40­70% of nucleotides in intergenic regions, untrans-
lated portions of mature mRNAs (UTRs) and most intronic DNA
are evolutionarily constrained relative to synonymous sites. How-
ever, I also use an extension to the McDonald­Kreitman test3
to
show that a substantial fraction of the nucleotide divergence in
these regions was driven to fixation by positive selection (about

Source: Andolfatto, Peter - Department of Ecology and Evolutionary Biology, Princeton University
Dean, Matthew D. - Department of Ecology and Evolutionary Biology, University of Arizona
Janzen, Fredric - Department of Ecology, Evolution, and Organismal Biology, Iowa State University
Nachman, Michael - Department of Ecology and Evolutionary Biology, University of Arizona

Collections: Biology and Medicine; Environmental Sciences and Ecology