Cancer quasispecies and stem-like adaptive aneuploidy

A new implication of quasispecies dynamics: Broad virus diversification in absence of external perturbations

RNA genetic elements include many important animal and plant pathogens. They share high mutability, a trait that has multiple implications for the interactions with their host organisms. Here we review evidence of a new adaptive feature of RNA viruses that we term "broadly diversifying selection". It constitutes a new type of positive selection without participation of any external selective agent, and which is built upon a progressive increase of the number of different genomes that dominate the population. The evidence was provided by analyses of mutant spectrum composition of two important viral pathogens, foot-and-mouth disease virus (FMDV) and hepatitis C virus (HCV) after prolonged replication in their respective cell culture environment. Despite being fueled by mutations that arise randomly and in absence of an external guiding selective force, this type of selection prepares the viral population for a response to selective forces still to occur. Since current evidence suggests that broadly diversifying selection is favored by elevated mutation rates and population sizes, it may constitute a more general behavior, relevant also to the adaptive dynamics of microbial populations and cancer cells.

Molecular evolution between chemistry and biology : The interplay of competition, cooperation, and mutation

Biological evolution is reduced to three fundamental processes in the spirit of a minimal model: (i) Competition caused by differential fitness, (ii) cooperation of competitors in the sense of symbiosis, and (iii) variation introduced by mutation understood as error-prone reproduction. The three combinations of two fundamental processes each, ([Formula: see text]) competition and mutation, ([Formula: see text]) cooperation and competition, and ([Formula: see text]) cooperation and mutation, are analyzed. Changes in population dynamics that are induced by bifurcations and threshold phenomena are discussed.