Does monohybrid mating affect the frequency of alleles in a population?

[Big-Daddy]

It would seem to me that after monohybrid mating, the frequency of the dominant and recessive allele should change? I will donate original frequency (i.e. proportion) by f₀ and that after mating by f₁.

f₁(Dom-Dom) = f₀(Dom-Dom)² + 1/2 * f₀(Dom-Dom) * f₀(Dom-Rec) + 1/4 * f₀(Dom-Rec)²

Am I right so far? (I hope my notation is intelligible - f₀(Genotype) is the fraction of the genotype, in the original population.)

Then we can replace the terms to find f₁(Dom-Dom) = P(Dom)⁴ + 1/2 * P(Dom)² * 2*P(Dom)*(1-P(Dom)) + 1/4 * (2*P(Dom)*(1-P(Dom)))² = P(Dom)⁴ - P(Dom)³ + P(Dom)².

Where P(Dom) is the frequency of the dominant allele and P(Rec) is the frequency of the recessive allele, P(Dom)+P(Rec)=1, in the original population. Thus it would seem that the frequency of the allele has changed due to the mating?

 

[Ygggdrasil]

It would seem to me that after monohybrid mating, the frequency of the dominant and recessive allele should change? I will donate original frequency (i.e. proportion) by f₀ and that after mating by f₁.

f₁(Dom-Dom) = f₀(Dom-Dom)² + 1/2 * f₀(Dom-Dom) * f₀(Dom-Rec) + 1/4 * f₀(Dom-Rec)²

You forgot a factor of 2 in the fraction of Dom-Dom/Dom-rec matings to account for the combinatorics [i.e. the probability of a homozygous dominant individual mating with a heterozygote is 2*f(Dom-Dom)*f(Dom-rec)].

 

[Big-Daddy]

You forgot a factor of 2 in the fraction of Dom-Dom/Dom-rec matings to account for the combinatorics [i.e. the probability of a homozygous dominant individual mating with a heterozygote is 2*f(Dom-Dom)*f(Dom-rec)].

Ah I see. And any mating between two individuals with different genotypes would also have this multiplying factor of 2 in the calculation of its probability?

 

[Ygggdrasil]

Ah I see. And any mating between two individuals with different genotypes would also have this multiplying factor of 2 in the calculation of its probability?

Yes.