Two Major Paths of Gene-Duplicates Evolution

Our analyses of several genomes indicate that in about 10% gene pairs, selection begins to guard a new gene copy very soon after a duplication event whereas the vast majority (90%) of extra genes remain redundant and unrecognised by selection. Such duplicates accumulate all mutations (including degenerative) in neutral fashion and are actually destined to become pseudogenes. We revealed this “two-stream” evolutionary pattern by the analysis of mutations in 2 versus 3 codon positions but not by the routinely used ratio of amino acid replacements (R) versus silent substitutions (S), i.e. the ‘2 vs. 3‘ metric proved to be more resolving than the traditional ‘R vs. S’ one for distinguishing neutrally evolving future pseudogenes from their functional counterparts controlled by negative selection.