Calculate phenotype frequencies in 5th generation

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1. Calculate phenotype frequencies in 5th generation. 2. Calculate allele frequencies in 5th generation. 3. Calculate genotype frequencies and number of moths in 5th generation

The correct answer and explanation is:

To calculate the phenotype frequencies, allele frequencies, and genotype frequencies in the 5th generation of a population, we will need some initial information, typically from a Hardy-Weinberg model or similar evolutionary framework. Here’s the outline:

Phenotype Frequencies in the 5th Generation

Phenotype frequencies are proportions of individuals expressing certain observable traits. If we know the population follows Mendelian inheritance and Hardy-Weinberg equilibrium, the dominant (A) and recessive (a) alleles’ impact on the phenotype can be modeled as:

  • Dominant phenotype (AA + Aa): p2+2pqp^2 + 2pq
  • Recessive phenotype (aa): q2q^2

Allele Frequencies in the 5th Generation

Allele frequencies are determined by the proportion of dominant (A) and recessive (a) alleles. If there’s no evolutionary pressure, the allele frequencies remain constant:

  • pp: frequency of allele A
  • qq: frequency of allele a
  • Relationship: p+q=1p + q = 1

Genotype Frequencies in the 5th Generation

Under Hardy-Weinberg equilibrium:

  • f(AA)=p2f(AA) = p^2
  • f(Aa)=2pqf(Aa) = 2pq
  • f(aa)=q2f(aa) = q^2

To determine number of moths, multiply these frequencies by the total population size.

Example Calculation (Assume p=0.6,q=0.4p = 0.6, q = 0.4, Population = 1000)

  1. Allele Frequencies (5th Generation):
    • p=0.6p = 0.6, q=0.4q = 0.4
  2. Genotype Frequencies:
    • f(AA)=0.62=0.36f(AA) = 0.6^2 = 0.36
    • f(Aa)=2(0.6)(0.4)=0.48f(Aa) = 2(0.6)(0.4) = 0.48
    • f(aa)=0.42=0.16f(aa) = 0.4^2 = 0.16
    Number of Moths:
    • AA: 0.36×1000=3600.36 \times 1000 = 360
    • Aa: 0.48×1000=4800.48 \times 1000 = 480
    • aa: 0.16×1000=1600.16 \times 1000 = 160
  3. Phenotype Frequencies:
    • Dominant phenotype: f(AA+Aa)=0.36+0.48=0.84f(AA + Aa) = 0.36 + 0.48 = 0.84
    • Recessive phenotype: f(aa)=0.16f(aa) = 0.16

Explanation

In evolutionary biology, understanding phenotype, allele, and genotype frequencies helps track population traits over generations. Assuming Hardy-Weinberg equilibrium, which posits no mutation, migration, genetic drift, selection, or non-random mating, allele frequencies remain constant across generations.

Phenotype frequencies are observed traits. For traits governed by simple dominance, the dominant phenotype includes homozygous dominant (AA) and heterozygous (Aa) genotypes. The recessive phenotype only appears in homozygous recessive (aa) individuals. By summing genotype contributions, phenotype proportions emerge.

Allele frequencies measure gene variants (A and a) within the population. A simple relationship p+q=1p + q = 1 exists, where pp is the frequency of A, and qq is the frequency of a. These frequencies are foundational, directly influencing genotype and phenotype proportions.

Genotype frequencies, derived using Hardy-Weinberg equations p2p^2, 2pq2pq, and q2q^2, describe the genetic structure. Population size allows calculation of individual counts for each genotype. These results reveal genetic diversity and the potential for phenotypic variation in a stable population.

In this example, with p=0.6p = 0.6, the dominant allele is more prevalent. Consequently, most moths exhibit the dominant phenotype, evident in genotype and phenotype distributions. These calculations provide insights into trait persistence or evolution under various pressures.

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