Impacts of inbreeding on genotype and allele frequencies

Let's develop an example to understand the impact of inbreeding on genotype and allele frequencies in a population. Under complete positive assortative mating or selfing, individuals mate with another individual possessing an identical genotype. Figure 2.12 diagrams the process of positive genotypic assortative mating for a diallelic locus, following the frequencies of each genotype through time. Initially, the frequency of the heterozygote is H but this frequency will be halved each generation. A Punnett square for two heterozygotes shows that half of the progeny are heterozygotes (H/2). The other half of the progeny are homozygotes (H/2), composed of one-quarter of the original heterozygote frequency of each homozygote genotype (H/2(1 - 1/2)). It is obvious that matings among like homozygotes will produce only identical homozygotes, so the homozygote genotypes each yield a constant frequency of homozygous progeny each generation. In total, however, the frequency of the homozygous genotypes increases by a factor

Genotype of H 2

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