Clonal interference occurs in asexual populations where beneficial mutations arising in different lineages compete with each other before being fixed, slowing the rate of adaptation. In sexual populations, beneficial mutations recombine and are fixed simultaneously, providing an advantage. Muller's model predicts that the rate of adaptation increases with population size and mutation rate until beneficial mutations interfere at larger rates. Experimental results show adaptive substitutions occur rarely regardless of these factors.

1. Clonal Interference and Evolution of RNA Viruses

3. 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.

4. 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.

5. 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.

6. 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.

7. Experimental Results.

9. 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.

10. 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.