Clonal interference

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This diagram illustrates how sex might create novel genotypes more rapidly. Two advantageous alleles A and B occur at random. The two alleles are recombined rapidly in a sexual population (top), but in an asexual population (bottom) the two alleles often arise in separate lineages and compete with each other.

Clonal interference is a phenomenon in the population genetics of organisms with significant linkage disequilibrium, especially asexually reproducing organisms. It occurs when two (or more) different beneficial mutations arise independently in different individuals. Prior to, or in the absence of genetic recombination, the mutations cannot be combined into a single more-fit genotype, but instead compete against each other. This typically leads to the loss of one of them,[1] confirming that the fate of an advantageous mutation can be determined by other mutations present in the same population.[2] In organisms with sexual reproduction, two beneficial mutations arising in different organisms can be combined in a descendant. This allows evolution to proceed more rapidly, a phenomenon known as the Hill-Robertson effect.

Clonal interference is named because an asexual lineage ("clone") with a beneficial mutation, which would likely be fixed if it occurred alone, may fail to be fixed, or even be lost, if another beneficial-mutation lineage arises in the same population; the multiple clones interfere with each other. This can also occur in cancer and pre-cancer cell lineages within a patient [3] .

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References[edit]

  1. ^ Marianne Imhof and Christian Schlötterer: Fitness effects of advantageous mutations in evolving Escherichia coli populations, Proc Natl Acad Sci U S A. 2001 January 30; 98(3): 1113–1117
  2. ^ Lang, G. I.; Rice, D. P.; Hickman, M. J.; Sodergren, E.; Weinstock, G. M.; Botstein, D.; Desai, M. M. (2013). "Pervasive genetic hitchhiking and clonal interference in forty evolving yeast populations". Nature. 500 (7464): 571–4. doi:10.1038/nature12344. PMC 3758440free to read. PMID 23873039. 
  3. ^ Baker AM, Graham TA, Wright NA (2013). Pre-tumour clones, periodic selection and clonal interference in the origin and progression of gastrointestinal cancer: potential for biomarker development. J Pathol 229(4): 502-514. doi: 10.1002/path.4157.