Considering all the dynamics of all four strains from population A in Fig \ref{621939}. Note that lines are colored according to strain rather than population. Strains can be divided into two discordant sets of non-overlapping alleles: {1, 1} and {2, 2}, and {1, 2} and {2, 1}. Each strain of a discordant set  behaves identically due to identical parametrization and no interaction between strains that do not share at least one allele, but discordant sets interact with one another due to partial cross-reactive immunity. Thus, when one set is abundant, the other is rare and vice versa. We highlight the maximum value of each discordant set's cycle with a vertical line in order to facilitate comparisons between strains and sets.