Book review: Quasispecies as a unifying concept in population dynamics

The quasispecies concept had two independent origins. One source was the theoretical ideas of Manfred Eigen and Peter Schuster in the 1970s. Studying the self-organization and evolution of primitive RNA molecules, they defined quasispecies as a distribution of mutant viral genomes generated by the mutation-selection process. In particular, the quasispecies nucleotide distribution consists of a singular fittest genotype, called the master sequence, surrounded by similar mutant spectra. The other source of the quasispecies concept can be traced to the growing empirical knowledge on RNA viruses formulated around the same time. Genomic sequencing of viral RNA indicated a variety of nucleotide sequences, or a distribution of sequences. Mutations in both Eigen’s theoretical system in the RNA viruses are not rare, as RNA is structurally less stable than RNA, but common, preventing the fittest genotype from becoming dominant. Virologists have adopted the quasispecies concept, with some papers on Covid-19 using the construct to explain that virus’s behavior.