This can result in stabilising selection through the purging of deleterious genetic polymorphisms that arise through random mutations.
[2][3] Purging of deleterious alleles can be achieved on the population genetics level, with as little as a single point mutation being the unit of selection.
In the case of strong negative selection on a locus, the purging of deleterious variants will result in the occasional removal of linked variation, producing a decrease in the level of variation surrounding the locus under selection.
Evidence supporting the masking theory has been reported in the single-celled yeast Saccharomyces cerevisiae.
[8] Further evidence of strong purifying selection in haploid tissue-specific genes, in support of the masking theory, has been reported for the plant, Scots Pine.