Non-synonymous versus synonymous substitutions in the depressant toxin family. dN over dS in intrafamilial comparisons of the leader and mature toxin coding domains. (A) Residue specific plot. Leader and mature residues are indicated by white and gray bars, respectively. Cysteine residues are indicated by yellow bars. (B) Matrix alignment plots were utilized to establish the correlation between the synonymous substitution rates and dN/dS ratios. Two lines distinguishes between values indicating positive (>1), neutral (0.6–1) and negative (<0.6) selections.