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

  • Thread starter Big-Daddy
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In summary, after monohybrid mating, the frequency of the dominant and recessive allele can change. This is represented by f1(Dom-Dom) = f0(Dom-Dom)2 + 1/2 * f0(Dom-Dom) * f0(Dom-Rec) + 1/4 * f0(Dom-Rec)2, with a factor of 2 included in the calculation to account for the combinatorics. This applies to any mating between two individuals with different genotypes.
  • #1
Big-Daddy
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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?
 
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  • #2
Big-Daddy said:
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)].
 
  • #3
Ygggdrasil said:
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?
 
  • #4
Big-Daddy said:
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.
 
  • #5


I can confirm that your understanding of monohybrid mating and its effects on allele frequency is correct. Monohybrid mating involves the crossing of individuals with different genotypes for a single trait. This can affect the frequency of alleles in a population because it introduces new combinations of alleles through the process of genetic recombination.

In your equation, f0 represents the original frequency of the alleles in the population, while f1 represents the frequency after mating. The terms in your equation represent the different possible genotypes that can result from monohybrid mating. As you correctly stated, the frequency of the dominant allele (P(Dom)) can change due to the combination of different genotypes through mating.

It is important to note that monohybrid mating alone may not significantly alter the frequency of alleles in a population. However, over time and with continued mating, it can contribute to the overall genetic diversity of a population.

In conclusion, monohybrid mating can affect the frequency of alleles in a population by introducing new combinations of alleles through genetic recombination. This is an important factor to consider in understanding the genetic makeup of a population and how it may change over time.
 

1. What is the Hardy-Weinberg principle?

The Hardy-Weinberg principle is a mathematical concept in population genetics that describes the relationship between allele frequencies and genotype frequencies in a population that is not evolving.

2. Why is the Hardy-Weinberg principle important?

The Hardy-Weinberg principle is important because it provides a baseline for understanding how genetic traits are inherited in a population. It can also be used to detect whether a population is evolving or if some factors are causing changes in allele frequencies.

3. What are the conditions for the Hardy-Weinberg principle to be applicable?

The Hardy-Weinberg principle is applicable when certain assumptions are met, including a large population size, random mating, no mutations, no migration, and no natural selection. These conditions are rarely met in real populations, but the principle provides a useful theoretical framework for understanding genetic inheritance.

4. How do you calculate allele frequencies using the Hardy-Weinberg principle?

Allele frequencies can be calculated using the Hardy-Weinberg equation: p^2 + 2pq + q^2 = 1, where p and q represent the frequencies of the two alleles in the population. p^2 represents the frequency of one homozygous genotype, q^2 represents the frequency of the other homozygous genotype, and 2pq represents the frequency of the heterozygous genotype.

5. What is an example of the Hardy-Weinberg principle in action?

An example of the Hardy-Weinberg principle in action is the inheritance of blood type in humans. The ABO blood group has three alleles (A, B, and O) and their frequencies can be calculated using the Hardy-Weinberg equation. In a population with random mating, the frequencies of these alleles should remain constant from generation to generation, unless there are external factors at play.

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