3.3 Evolution rate
Because outlier genes with larger dN/dS may generate deviations in evaluating the overall selective constraint for species, we filtered our dataset to remove genes with dN/dS>100. The rest of genes were used to evaluate the overall selective constraints in the species analyzed. The dN/dS value was calculated for each species in this study (Figure 3). Higher dN/dS values in species of the macrotis group (R. episcopus : 0.2919, R. siamensis : 0.3723, R. osgoodi : 0.3355, R. rex : 0.2742, R. marshalli : 0.2683) than other species (R. pusillus : 0.225, R. sinicus : 0.2524, H. armiger : 0.217) demonstrated that the majority of genes experienced purifying selection on other species, suggesting that genes evolved at a higher rate in the species of the macrotisgroup.