Asymmetry of substitution rates in paralogs. A: The distribution of Ka asymmetry in paralogous clade (red) relative to simulated asymmetry based on random placement of substitutions on the two clades (black). B: The portion of pairs of paralogs in which the observed asymmetry is either low (green) or significantly high (red, adjusted χ2 test P value <0.05 after Bonferroni correction). C. Substitution rates asymmetry of in paralogous clades vs. Ka values observed in the orthologous singleton clade, binned at 0.05 unit intervals on the logarithmic scale. Vertical bars are standard errors. Black lines: expected asymmetry in case of the shape parameter of gamma-distribution of substitution rate among amino acid sites 2 (top line) and 0.5 (bottom line). Linear regressions drawn through all points with different upper-bound duplication age estimate of duplication ages (colours as on Figure 2).