Figure 2. Annual diversity among accessory genomes.

The diversity was calculated between strains collected within the same year. Using a binary measure of the presence (1) or absence (0) of a gene in each accessory OG, diversity among strains was calculated by applying the distance measure described by Dutilh et al.⁴⁷. Core OG diversity was determined by comparing the pairwise distances between isolates from the phylogenetic tree per year. Circles: means accessory distance; diamonds: means core OG distance; whiskers: 95% confidence intervals.