Figure 4.

Gene duplicability dependent on degrees. Correlation between the degree and the duplicability of proteins in the (A) yeast, (B) worm, (C) fly, (D) human, and (E) malaria parasite PINs. L, M, and H represent low- (k = 1), middle- (k = 2-6), and high-degree (k > 7) proteins, respectively. A vertical axis indicates the mean duplicability in each category. A species name above each diagram denotes the species with which the orthologous relationships were examined. For example, in the top left diagram in (A), gene duplicabilities were investigated using a phylogenetic tree containing S. cerevisiae and S. paradoxus genes. In (A) and (C), the results for MIPS and Rual et al. datasets, respectively, are shown, and those for other yeast and human datasets are provided in Additional file 5: Figure S5. In each diagram, the duplicability of proteins in each category is compared to one another by using the Wilcoxon rank-sum test with the Bonferroni correction. *, P < 0.05; **, P < 0.01; ***, P < 0.001.