Therefore, the 0 locus heterozygote frequency is weighted by a factor of 2, as shown in Table 9.5.

Each of the individuals carrying an M1/M1 marker locus genotype will have a genotypic value that depends on the genotype at the 0TL locus. It is customary to use an arbitrary scale of measurement for the genotypic values (see section 10.1). On this scale, the genotypic value of the 0101 genotype is assigned +a, the genotypic value of the 0202 genotype is assigned -a, and the genotypic value of the 0102 genotype is assigned d (refer to Fig. 10.1).

The point exactly mid-way between the genotypic values of the homozygotes, called the midpoint, is defined to be zero. When the genotypic value of the heterozygote is at the midpoint, d = 0. The degree of dominance can be expressed as the ratio of d/a. Using

M0, this scale to measure genotypic values, the —


genotype a genotype has a value of +a, the

0 0

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