A. Proportions of ancestry from groups A, B1, B2 and D as inferred by STRUCTURE and their assignment to six groups as displayed with DISTRUCT (). The plot shows one vertical line for each isolate indicating the proportions of ancestry from the four groups, colour-coded as in part B.
B. Distribution of A, B1, B2, D, AxB1 and ABD within a minimal spanning tree (MSTREE) of 275 E. coli STs based on the degree of allele sharing. Dots are coloured according to group and lines connecting ST complexes (see ) are shaded in grey. Clades that are illustrated in greater detail in part c are indicated by numbers and encircled by lines.
C. Details of microevolution within eight selected clades. The branch order within each clade and the ancestral ST were taken from the MSTREE. Boxes are colour-coded as in panel B and indicate stretches of nucleotides that are derived from the four ancestral groups A, B1, B2 and D within each of the seven loci, shown in the order: adk, fumC, gyrB, icd, mdh, purA and recA. Numbers in contrasting colours indicate the numbers of nucleotides that differ from the allele that was previously present.