Complexity of Gene Expression Evolution after Duplication: Protein Dosage Rebalancing

The concept of genetic balance traces back to the early days of genetics. With the increasing availability of genomic data, it became clear that numerous gene families have diverged in function through series of duplications, including many lineage specific expansions (or gene copy-number variations, CNVs, at the population level). This is not surprising taking into account that gene duplications are traditionally considered to be a major evolutionary source of new protein functions Results of large-scale analyses of gene duplications are best consistent with the following possible scenario of gene duplications: many recent gene duplications/CNVs have a positive effect in some tissues and/or environmental conditions, whereas they also have a negative effect in some other tissues and/or environmental conditions. It seems likely that balancing of positive and negative dosage effects is an important factor which is causing diversification of expression patterns (rebalancing of expression) of duplicate genes in the course of fixation of gene duplications.