Universals of genome and molecular phenome evolution.

The figure shows idealized versions of universal dependencies and distributions. The scattered points show the range of characteristic variance. (A) Log-normal distribution of evolutionary rates of orthologous genes. (B) Anticorrelation between gene expression level (protein abundance) and sequence evolution rate. (C) Power law–like distribution of paralogous family size. (D) Differential scaling of functional classes of genes with the total number of genes in a genome. Three fundamental exponents are thought to exist: 0 – no dependence, typical of translation system component; 1 – linear dependence, characteristic of metabolic enzymes; 2 – quadratic dependence, characteristic of regulatory and signal transduction system components.