Figure 3. High degree of genomic similarity among PMEN1 strains.

Grouping of 51 S. pneumoniae strains based on (A) the number of distributed genes or (B) the number of variable core alleles. These trees provide a measure of the genic or alleic distance between strains without making any inference regarding their phylogeny, since the high rates of recombination within the population can interfere with population-wide phylogenetic results. The PMEN1 genomes are more closely related to one-another than any one isolate is to any other independently isolated strains.