Correlations between Quantitative Measures of Genome Evolution, Expression and Function

In addition to multiple, complete genome sequences, genome-wide data on biological propproperties of genes, such as knockout effect, expression levels, protein-protein interactions,and others, are rapidly accumulating. Numerous attempts were made by many groups to examine connections between these properties and quantitative measures of gene evolution. The questions addressed pertain to the most fundamental aspects of biology: what determines the effect of the knockout of a given gene on the phenotype (in particular, is it essential or not) and the rate of a gene’s evolution and how are the phenotypic properties and evolution con-nected? Many significant correlations were detected, e.g., positive correlation between the ten-dency of a gene to be lost during evolution and sequence evolution rate, and negative correla-tions between each of the above measures of evolutionary variability and expression level or the phenotypic effect of gene knockout. However, most of these correlations are relatively weak and explain a small fraction of the variation present in the data. We propose that the majority of the relationships between the phenotypic (“input”) and evolutionary (“output”) variables can be described with a single, composite variable, the gene’s “social status in the genomic community”, which reflects the biological role of the gene and its mode of evolution. “High-status ” genes, involved in house-keeping processes, are more likely to be higher an