Figure 2: Variations of relative synonymous codon usage (RSCU) values for actin genes within groups (black columns) and species (red columns) in each codon. Each column represents average variations of all groups (or species) for one codon. For all the 59 codons, the red columns are significantly higher than black ones (P < 0.001 for all codons, detailed corresponding P value for each codon see Table S4 in Supplementary Material available online at http://dx.doi.org/10.1155/2013/630803), representing that the codon usage patterns of actin genes within species were very distinct among each other, while those of actin genes within groups were much similar.