Question

A recessive allele for blue eyes (b) has a frequency of .3 in population 1 and a frequency of .15 in population 2. Pollution causes a number of people in population 1 to go to population 2. After they migrate 35% of the people in population 2 consist of people from population 1. What would be the frequency of blue eyes in population 2 after the migration

Answer 1

Answer:

The frequency of blue eyes in population 2 after the migration is q₂´ = 0.195 ≅ 0.2

Explanation:

Whenever migration, m, occurs between two populations, there is genetic flow going on. Genetic flow is an evolutive strength only if migration > 0 and if the allelic frequency in one generation is different from the allelic frequency in the next generation.

Genetic flow acts homogenizing the allelic frequencies between the two populations, and it might introduce variability into the new one.

For genetic flow to be possible, there needs not only the movement of the genes from one population to the other but also the reproduction process on the new population. Hence, it involves an interaction between the dispersion pattern and the reproductive system.

Available data:

• Population 1 → frequency of the recessive allele b = 0.3
• Population 2 → frequency of the recessive allele b = 0.15
• m = proportion of gametes coming from the population 1  = 30% = 0.3
• 1-m = proportion of gametes that remain in the population
• p = frequency of the dominant allele in population 1 before migration
• q = frequency of the recessive allele in population 1 before migration
• p´ = frequency of the dominant allele in population 2 after migration
• q´ = frequency of the recessive allele in population 2 after migration

To calculate the frequencies of the gametes (p1, q1, p2, q2) after migration, we can use the following equations:

• p₁’ = p₁ (1 - m) + p₂ x m
• q₁´ = q₁ (1 - m) + q₂ x m
• p₂’ = p₂ (1-m) + p₁ x m  
• q₂´ = q₂ (1 - m) + q₁ x m

So to know the frequency of blue eyes in population 2 after the migration, we just need to replace the terms in the equation for the given values, and then calculate q₂´.

q₂´ = q₂ (1 - m) + q₁ x m

q₂´ = 0.15 (1 - 0.03) + 0.3 x 0.3

q₂´ = 0.105 + 0.09    

q₂´ = 0.195 ≅ 0.2