Sagot :
The recessive allele frequency increased (q = 0.97) and the dominant one decreased (p = 0.03). Genotypic frequencies followed this tendency too (q² =0.94, 2pq = 0.058 and p² = 0.001). The Carbonaria phenotype decreased to 0.06, while Typica showed a frequency of 0.94.
------------------------------------------
Available data:
- Some moths were released in the forest (N=1000). 810 were white, and 190 were black.
- The color is defined by a single diallelic gene. The dominant allele -D- codes for black color (carbonaria), while the recessive allele -d- codes for white (Typica).
- These individuals produced five new generations since they were released, G1, G2, G3, G4, G5.
Moths realesed G1 G2 G3 G4 G5
Typica 810 405 468 569 691 857
Carbonaria 190 72 66 64 61 56
Total 1000 477 534 633 752 913
Phenotype frequencies
Color Initial Frequency G5 Frequency
Typica white 0.81
Carbonaria Black 0.19
Allele Frequencies
Allele Initial Allele Frequency G5 Allele Frequency
q d �� 0.9
p D 0.1
Genotype Frequency
Moths Genotype Color Released Initi.Freq. G5 Freq. Nº F5 moths
q² Typica dd White 810 0.81
2pq Carbon. Dd Black 180 0.18
p² Carbon. DD Black 10 0.01
This information is guiding you to know how to calculate frequencies and total numbers. Information about released individuals is an example of how you need to proceed.
Firts, we will assume that this population is under Hardy-Weinberg equilibrium. So let us review some theoretical framework.
- The allelic frequencies in a locus ⇒ p and q ⇒ dominant and
recessive alleles.
- The genotypic frequencies after one generation are p² (H0m0zyg0us dominant), 2pq (Heterozyg0us), q² (H0m0zyg0us recessive).
- If a populations is in H-W equilibrium, it will get the same allelic frequencies generation after generation.
- The sum of allelic frequencies equals 1 ⇒ p + q = 1.
- The sum of genotypic frequencies equals 1 ⇒ p² + 2pq + q² = 1
Now let us analyze the problem.
We need to get information on G5 generation. We will do it step by step.
1) Phenotype frequencies
To get the Phenotype frequencies, we just need to divide the number of individuals with each phenotype by the total number of individuals in this generation. So,
- Total number of individuals in G5 → 913
- White = Typica = 857 individuals
- Black = Carbonaria = 56 individuals
⇒ F(Typica) = 857 / 913 = 0.938 ≅ 0.94
⇒ F(Carbonaria) = 56 / 913 = 0.061 ≅ 0.06
2) Allelic Frequencies
We can use the phenotypic frequencies to get the allelic frequencies.
Remember that carbonaria (black) moths include h0m0zyg0us dominant (DD) and heter0zyg0us (Dd) individuals. So we can not get the allelic frequencies from this data.
We can only use the allelic frequency of Typica (White) individuals. Typica phenotypic frequency only includes h0m0zyg0us recessive individuals, dd.
We know that,
- H0m0zyg0us recessive genotype → dd
- Genotypic frequency → F(dd) → Represented as q²
- F(Typica) = F(dd) = q² = 0.94
- Recessive allele → d
- Recessive allelic frequency → f(d) → Represented as q
- f(d) = q = ??
q² = 0.94
q = √ 0.94
q = 0.969 ≅ 0.97
0.97 is the recessive allelic frequency. Now we should calculate the dominant allelic frequency. To do this, we will clear the following formula,
p + q = 1
p + 0.97 = 1
p = 1 - 0.97
p = 0.03
So, now we also know that
⇒ f(D) = p = 0.03
⇒ f(d) = q = 0.97
3) Genotypic Frequencies
Now, we need to get the genotypic frequencies, F(xx)
⇒ F(DD) = p² = 0.03² = 0.0009 ≅ 0.001
⇒ F(Dd) = 2pq = 2 x 0.03 x 0.97 = 0.058
⇒ F(dd) = q² = 0.97² = 0.9409 ≅ 0.94
4) Number of individuals
Finally, we need to tell the number of individuals with each genotype. We just need to multiply each frequency by the total number of individuals in G5.
- F(DD) = p² = 0.001
- F(Dd) = 2pq = 0.058
- F(dd) = q² = 0.94
- Total number of individuals = 913
⇒ DD Black -Carbonaria- individuals → 0.001 x 913 = 0.913 ≅ 0.91
⇒ Dd Black -Carbonaria- individuals → 0.058 x 913 = 52.954 ≅ 53
⇒ dd White -Typica- individuals → 0.94 x 913 = 858.22 ≅ 858
From this results, we can conclude that the moths population is not in H-W equilibrium, because their allelic and genotypic frequencies changed through generations.
It seems that Natural selection is favoring the recessive phenotype by increasing the frequency of the recessive allele over the dominat one. Probably directional selection is acting on this population.
----------------------------------
Related link: https://brainly.com/question/12724120?referrer=searchResults