Lack of phylogenetic conservatism of Bacillus anthracis plasmid copy number. Lack of phylogenetic conservatism of Bacillus anthracis plasmid copy number. A dendrogram was constructed based on the average nucleotide identity (ANI) distances calculated for 412 B. anthracis strains. Presence or absence of pXO1 (inner circle in blue) and pXO2 (inner circle in red) and estimated plasmid copy number data (bar plots) are shown. Strains with high and low plasmid copy numbers were found to be dispersed across the three main clades, i.e., clade A (n = 397), clade B (n = 12), and clade C (n = 3), and no apparent clusters were evident. The tree scale corresponds to 1 − ANI distance. Angela Pena-Gonzalez et al. mSystems 2018; doi:10.1128/mSystems.00065-18