Quasi-species evolution in subdivided populations favours maximally deleterious mutations

Abstract

Most models of quasi-species evolution predict that populations will evolve to occupy areas of sequence space with the greatest concentration of neutral sequences, thus minimizing the deleterious mutation rate and creating mutationally 'robust' genomes. In contrast, empirical studies of the principal model of quasispecies evolution, RNA viruses, suggest that the effects of deleterious mutations are more severe than in similar DNA-based microbes. We demonstrate that populations divided into discrete patches connected by dispersal may favour genotypes where the deleterious effect of non-neutral mutations is maximized. This effect is especially strong in the absence of back mutation and when the amount of time spent in hosts prior to dispersal is intermediate. Our results indicate that RNA viruses that produce acute infections initiated by a small number of virions are expected to evolve fragile genetic architectures when compared with other RNA viruses.

Survival of the steepest: hypersensitivity to mutations as an adaptation to soft selection

“…There is a similarity with the model of O’Fallon et al. (2007), however, in that we both have two stages of selection: in O’Fallon et al. (2007) because of migration between different subdivided populations, in which selection occurs first within a group and then in the whole population; in my model instead selection occur first during development and then in the adult phase, with no migration and no subdivided populations.…”

“…O’Fallon et al. (2007) show that populations divided into discrete patches connected by dispersal may also favour antirobust genotypes.…”

“…(2007) are concerned primarily with microbes, in particular RNA viruses, whereas my model applies to multicellular organisms. There is a similarity with the model of O’Fallon et al. (2007), however, in that we both have two stages of selection: in O’Fallon et al.…”

“…This is similar to Levene’s (1953) metapopulation model, and a similar scenario (populations evolving separately before competing) is described in my competition simulation, where I show that the effects of juvenile soft selection are similar to the effects of independent selection within sub‐populations before competition. O’Fallon et al. (2007) are concerned primarily with microbes, in particular RNA viruses, whereas my model applies to multicellular organisms.…”

“…The difference with juvenile selection is that this first phase of selection occurs in different locations and the sub‐population then migrate to a common location where competition occurs (see Levene, 1953; a similar scenario has been modelled by Wilke et al. , 2001 and O’Fallon et al. , 2007); moreover here multiple rounds of selection are possible.…”