GIANT POPULATIONS. “An important aspect of the quasispecies concept is that the large size of virus populations enables positive and negative interactions between individual viruses to establish a quasi-equilibrium of the variant proportions. Genetic variation is generated by the accumulation of mutations during replication and their re-arrangement by genetic recombination, and genome segment reassortment in the case of segmented genomes.”
http://www.sciencedirect.com/science/article/pii/S0042682215001580