In diploid eukaryotes, this is a consequence of the system of sexual reproduction, where mutant alleles get partially shielded, for example, by the selective advantage of heterozygotes.

• 在二倍体真核生物中，这是有性繁殖的结果；比如，有性繁殖时突变的等位基因被杂合子的选择性优势部分地屏蔽。