Polymorphism in an inbreeding population under models involving underdominance.

Models of selection favoring homozygotes over the heterozygotes and involving frequency-dependency in their competitive abilities were simulated in order to determine the conditions for maintaining stable polymorphism at a diallelic locus in large inbreeding populations. With heavier inbreeding, frequency-dependency could increasingly override the effects of underdominance in both pure stand and the competing ability components of fitness in terms of yielding stable nontrivial equilibriums. The significance of such selection models is discussed for the retention of variability in inbreeding populations with a minimum of segregational load and higher overall stability in contrast to the overdominance models.