Figure 3: Minimum spanning tree of 31 French B. anthracis strains belonging to the A.Br.011/009 canSNP subgroup

Minimum spanning tree of 31 French B. anthracis strains belonging to the A.Br.011/009 canSNP subgroup (obtained with BioNumerics 6.6 from Applied Maths). Data are based on 560 chromosomal SNPs (A), 20 pXO1 SNPs (B) and 18 pXO2 SNPs (C). The six resolved branches are color-coded. The diameter of each circle varies according to the number of isolates having the same genotype. The length of each branch is proportional (logarithmic scale) to the number of SNPs identified between strains. Indicated in red are the positions and names for two canSNPs described in this study. NE: North-East, SW: South-West, SE: South-East. Based on a parsimony approach, the tree size is 561, i.e. it contains approximately 0.18% of homoplasia. Concerning the plasmids, the tree sizes are 20 and 18 for pXO1 and pXO2, respectively, i.e. it contains no homoplasia.

本研究构建的最小生成树（minimum spanning tree, MST）包含31株法国源炭疽芽孢杆菌（Bacillus anthracis）菌株，所有菌株均隶属于A.Br.011/009 canSNP亚组，分析过程采用Applied Maths公司的BioNumerics 6.6软件完成。本数据集以560个染色体单核苷酸多态性（single nucleotide polymorphism, SNP）位点（组A）、20个pXO1质粒单核苷酸多态性位点（组B）以及18个pXO2质粒单核苷酸多态性位点（组C）作为分析基础。图中6个解析得到的进化分支均采用颜色编码标识。每个圆圈的直径与携带相同基因型的分离菌株数量呈正相关；各分支的长度以对数尺度计算，与菌株间鉴定出的单核苷酸多态性位点数量成正比。本研究报道的2个canSNP位点的位置与名称以红色标注。缩写说明：NE：东北（North-East），SW：西南（South-West），SE：东南（South-East）。基于简约法（parsimony approach）分析，该染色体最小生成树的树长为561，其中约包含0.18%的同塑性（homoplasia）变异。针对pXO1和pXO2质粒，其对应最小生成树的树长分别为20和18，未检测到同塑性变异。