In this paper, we investigate two mechanisms that may help to explain these observations: (1) a high genomic mutation rate to recessive lethal alleles, and (2) selective interference among loci with deleterious recessive mutations under partial selfing.
Selective Interference and the Threshold Selfing Rate for Purging Recessive Lethals
Selective interference among loci with deleterious recessive mutations occurs under partial selfing because inbreeding depression reduces the fitness of viable selfed genotypes at individual loci, decreasing the opportunity for selection produced by self-fertilization.
Because of selective interference among loci, and because partial selfing creates identity disequilibrium (positive associations between homozygous genotypes at different loci, even in the absence of linkage; Haldane 1949; Weir and Cockerham 1973), it is difficult to analyze an exact model of the maintenance of high inbreeding depression by recessive lethal mutations.
It also has some advantages over the Kondrashov model for analyzing selective interference among loci, completely recessive lethals, and parameter variation among loci.