The Muller's ratchet in evolutionary genetics refers to a procedure by which gathering of harmful mutations takes place in an irreversible way by the genomes of an asexual population. Muller suggested this process as one of the cause that why sexual reproduction can be considered over to asexual reproduction.
The main influence of Muller's ratchet is the gathering of somewhat deleterious mutations. Such gathering of mutation can at certain occasions result in eventual extinction.
This takes place if population size is finite, recombination is absent, slightly deleterious rates of mutations are high, almost no back mutations takes place, and purifying selection is very weak to eradicate all the novel deleterious mutations.
