Modification of Gene Duplicability during the Evolution of Protein Interaction Network
Figure 2
Origin, conservation, and duplicability of genes in evolution.
(A) The percentage of genes that originated at each internal nodes of the tree of life is shown for the four species used in the analysis, and for seven additional species. The group-specific nodes correspond to primates for H. sapiens, rodents for M. musculus, birds for Gallus gallus, fishes for D. rerio, nematodes for C. elegans, insects for D. melanogaster and A. mellifera, fungi for S. cerevisiae and Schizosaccharomyces pombe, and bacteria for E. coli and Bacillus subtilis. The lack of specific genes for C. elegans, G. gallus and M. musculus is likely an artifact due to presence in EggNOG of few species for the corresponding group-specific nodes. LUCA, last universal common ancestor; euk, eukaryotes; opi, opisthokonts; met, metazoans; ver, vertebrates. (B) The percentage of genes that have the same conservation is shown for each species. Conservation is measured as the number of internal nodes where no ortholog is found since the gene appeared. In all species, conservation ranges from 0 (i.e. no missing node) to 5 (i.e. the gene originated with LUCA and has orthologs only in prokaryotes and in the group-specific cluster). Since only few genes have conservation 5, we grouped them with genes with conservation 4. (C) The percentage of singleton and duplicated genes is shown for all eleven species.