Fig. 4

Codon-based measure of evolutionary pressure on M. catarrhalis prophage genes. The d_N/d_S value for each codon (represented by each blue +) is plotted against the length of each prophage gene encoding large terminase subunit, integrase, and portal. Similarly, the d_N/d_S value for each codon is plotted for the concatenation of 7 M. catarrhalis MLST housekeeping genes. An average value for four subsequent codons is represented by the red line. Values of d_N/d_S < 1 indicates purifying selection, d_N/d_S > 1 indicates diversifying selection, and d_N/d_S = 1 indicates neutrality