Figure 4
From: Chance and necessity in the genome evolution of endosymbiotic bacteria of insects
Endosymbiotic bacteria of insects converge in their selective constraints at genes that are unrelated to the insect host. We analyzed the distribution of the selective constraints among endosymbiotic genes and studied the convergences among the five independent endosymbiotic groups. We studied two sets of genes, (a) one in which the ratio between the symbiotic and free-living bacterial non-synonymous-to-synonymous rates ratio (R=ωe/ωf) is R<2, hence this set includes genes with strong selective constraints (R<1) and slightly relaxed constraints (1<R<2), and (b) a set of strongly constrained symbiotic genes when compared with their free-living bacterial orthologs R<1. Gray-colored squares in the matrix indicate genes convergently constrained between two or more endosymbiotic groups; white squares are genomes in which such genes are under relaxed constraints. (c) Convergently constrained genes in endosymbiotic genomes. These genes are color-coded according to their functional classification using GO terms. Only seven genes were relevant to the metabolism of the bacterial host (green-colored genes).
