Editing Molecular evolution (section)

===Gene conversion===

{{Main|Gene conversion}}

Gene conversion occurs during recombination, when nucleotide damage is [[DNA repair|repaired]] using  an homologous genomic region as a template. It can be a biased process, i.e. one allele may have a higher probability of being the donor than the other in a gene conversion event. In particular, GC-biased gene conversion tends to increase the [[GC-content]] of genomes, particularly in regions with higher recombination rates.<ref name="Duret_2009">{{cite journal | vauthors = Duret L, Galtier N | title = Biased gene conversion and the evolution of mammalian genomic landscapes | journal = Annual Review of Genomics and Human Genetics | volume = 10 | pages = 285–311 | year = 2009 | pmid = 19630562 | doi = 10.1146/annurev-genom-082908-150001 }}</ref> There is also evidence for GC bias in the mismatch repair process.<ref name="Galtier_2001">{{cite journal | vauthors = Galtier N, Piganeau G, Mouchiroud D, Duret L | title = GC-content evolution in mammalian genomes: the biased gene conversion hypothesis | journal = Genetics | volume = 159 | issue = 2 | pages = 907–911 | date = October 2001 | pmid = 11693127 | pmc = 1461818 | doi = 10.1093/genetics/159.2.907 }}</ref> It is thought that this may be an adaptation to the high rate of methyl-cytosine deamination which can lead to C→T transitions.

The dynamics of biased gene conversion resemble those of natural selection, in that a favored allele will tend to increase [[Exponential growth|exponentially]] in frequency when rare.