Figure 1

Chances of survival upon gene-KO/KD vary between organisms. While the number and fraction of duplicate genes increases from prokaryotes to single- and multi-cellular eukaryotes, the fraction of essential genes (and hence chances of survival upon gene-KO/KD) vary widely. The three panels show the probability of survival P(S)(A), the gene family distribution and number of genes with duplicates (D ≥ 1)(B). Singleton genes are labeled D = 0, members of two-gene families are labeled D = 1, members of larger gene families are labeled D ≥ 2. Red bars indicate values for all genes, as also listed in Table 1. High (black) and low (white) gene expression levels are estimated by codon bias indices (see methods). Significant differences between genes of high and low expression (χ² test) are marked with ** (P-value ≤ 0.01) and *** (P-value ≤ 0.001). D – effective gene family size (number of additional duplicates of a gene); S – survival upon gene deletion (1-essentiality). Mgen – Mycoplasma genitalium; Hpyl – Helicobacter pylori; Hinf – Haemophilus influenzae; Mtub – Mycobacterium tuberculosis; Paer – Pseudomonas aeruginosa; Bsub – Bacillus subtilis; Ecol – Escherichia coli; Scer – Saccharomyces cerevisiae (yeast); Cele – Caenorhabditis elegans (worm); Dmel – Drosophila melanogaster (fly); Mmus – Mus musculus (mouse).