Coefficient of variations (CVs) of gene expression values for actin genes within groups (black columns) and species (red columns) in each tissue. Each column represents average CVs of all groups (or species) for one tissue. For all the five tissues, the black columns are significantly lower than red ones, indicating that the actin genes within groups exhibited similar expression patterns, while actin genes within species did not (P < 0.001, using two-tailed t-test).
