Gene Expression Level and Single Nucleotide Polymorphism Rates

Proteins in the same species evolve at different rates so the systems evolutionary genomics field studies the factors that determine the evolutionary rates of proteins. In the last thirty years, due to the lack of the sequence data, the evolutionary theory suggested that protein evolutionary rates are controlled by the density of amino acid residues in a protein under the influence of their functional importance. Recently, after the genome-scale data of sequences, some genomic factors demonstrate weak but statistically significant correlations with evolutionary rates. Among the genomic factors, in unicellular organisms, the expression level is the most prominent negative correlate with evolutionary protein rate.