Underdominance
= Underdominance
{wiki}
= Heterozygote disadvantage
{synonym}
<Underdominance> means that the <heterozygote> has lower <genotype fitness> than both corresponding <homozygotes>. In a deterministic randomly mating biallelic population, it produces an unstable interior allele-frequency threshold separating the two fixation outcomes, unlike <heterozygote advantage>.