Complexity of Gene Expression Evolution after Duplication: Protein Dosage Rebalancing

Figure 2

Schematic representation of the “protein dosage rebalancing” hypothesis [34]. This synthetic model is a combination of the dosage effect and DDC models: many recent gene duplications (or gene copy-number variations (CNVs) at the population level) 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 [3, 7, 21–23]. Balancing of positive and negative dosage effects influenced by natural selection may be an important factor which is causing diversification of expression patterns (rebalancing of expression) of duplicate genes in the course of fixation of gene duplications. This process is similar to the conventional dosage effect hypothesis [3]. After the gene duplication is fixed in a population, preservation of this gene duplication may be largely explained by the DDC model (maintenance of duplicate genes due to differential loss or reduction of expression in various tissues).