The relationship between gene density and proportion of DPGs among eukaryotic genomes. The divergent ratio was calculated by dividing the number of DPGs over the total number of genes in a genome. The species among various lineages including vertebrates, insects, nematodes, fungi, and plants are indicated with solid circles in red, blue, orange, magenta, and green, respectively. The dished line is added to indicate linear regression. The gene densities of insects and vertebrates are much lower than other eukaryotes and the Drosophila species have slightly higher proportions of DPGs than the vertebrates.