RT Journal
A1 Conant, Gavin C.
A1 Wagner, Andreas
T1 Asymmetric Sequence Divergence of Duplicate Genes
JF Genome Research 
JO Genome Research 
YR 2003 
FD September 01 
VO 13 
IS 9 
SP 2052 
OP 2058 
DO 10.1101/gr.1252603 
UL http://genome.cshlp.org/content/13/9/2052.abstract 
AB Much like humans, gene duplicates may be created equal, but they do not  stay that way for long. For four completely sequenced genomes we show that  20%–30% of duplicate gene pairs show asymmetric evolution in the amino  acid sequence of their protein products. That is, one of the duplicates  evolves much faster than the other. The greater this asymmetry, the greater  the ratio Ka/Ks of amino acid substitutions  (Ka) to silent substitutions (Ks) in a gene pair. This  indicates that most asymmetric divergence may be caused by relaxed selective  constraints on one of the duplicates. However, we also find some candidate  duplicates where positive (directional) selection of beneficial mutations  (Ka/Ks > 1) may play a role in asymmetric divergence.  Our analysis rests on a codon-based model of molecular evolution that allows a  test for asymmetric divergence in Ka. The method is also more  sensitive in detecting positive selection (Ka/Ks > 1)  than models relying only on pairwise gene comparisons.