High redundancy and little new functionality among duplicated genes in yeast

PLoS Genetics published today a paper by Dean, J., Davis, J.C., Davis, R.W., and D.A. Petrov on the pervasive redundancy and apparent lack of new functionality among duplicated genes in yeast. We built a large number of yeast strains carrying single and double gene deletions of duplicated genes and measured their growth rates in rich medium. Using these data, we determined that many duplicated genes are functionally redundant to a substantial degree. We also demonstrated that the fitness effects of double deletions of duplicate genes are indistinguishable from our best estimate of the fitness effects of deletions of their ancestral singleton genes. We therefore argued that many duplicate genes do not gain substantial new functionality at least in the rich medium. Our results suggest that subfunctionalization does not generally proceed to completion, even after very long periods of time, and that neofunctionalization is either rare or of little consequence, at least under some growth conditions. This work was a collaboration between the Petrov and Davis labs.