Clonal Interference and Evolution of RNA Viruses

Clonal Interference In Sexual and Asexual Populations.

In asexual populations, the beneficial mutations occurring in different lineages compete with each other before being expressed termed as clonal interference.

Clonal interference makes it clear that the fixed characters are of large effects. As clonal interference takes time for the fixation of characters it slows down the rate of adaptation in asexual reproduction.

Clonal Interference In Sexual Population

In sexual populations, the beneficial mutations that occurring in the lineages recombine with each other and are fixed together. So there is a simultaneous fixation of mutations in sexual population.

Simultaneous fixation event is an advantage of sexual reproduction.

Muller's model

1. Probability of the fixation of mutation decreases with the population size and mutation rate.

2. As population size or mutation rate increases, adaptive substitutions can result in the fitness increase.

3. The rate of adaptation increase is a function of both population size and mutation rate.

4. Beneficial mutations commonly found don't achieve fixation as they interfere at larger rates.

Predictions Made Through Muller's Model

1. For the increasing population sizes, fitness effect associated with the fixed beneficial mutations were large.

2. Rate of adaptation of the population after mutations tends to a limit.

Experimental Results.

Conclusion

1. Adaptive substitutions occurs as discrete, rare events , regardless of population size and mutation rate.

2. In medium to large population, the rate of fitness increase is hardly affected by changes in either population size or mutation rate.

References

Miracles, Rosario et al. "Clonal interference and the evolution of RNA viruses." Science 285.5434 (1999): 1745-1747.

Kao, Katy C, and Gavin Sherlock. "Molecular characterization of clonal interference during adaptive evolution in asexual populations of Saccharomyces cerevisiae." Nature genetics 40.12 (2008): 1499-1504.

de Vassar, J Arjan GM, and Daniel E Rosen. "Clonal interference and the periodic selection of new beneficial mutations in Escherichia coli." Genetics 172.4 (2006): 2093-2100.