Fig. 2From: Genome-wide signals of positive selection in strongylocentrotid sea urchinsDistributions of rates of nonsynonymous (d N) and synonymous (d S) substitutions and d N/d S ratios for the a positive selected genes (PSGs; n = 1008), b genes not showing positive selection (non-PSGs; n = 5512), and c all genes (n = 6520)Back to article page