A completely recessive allele (Q1 ) has a frequency of 0.7 in a large population

Question

A completely recessive allele (Q1 ) has a frequency of 0.7 in a large population, and the Q1 Q1 homozygote has a relative fitness of 0.6.

a. What will be the frequency of Q1 after one generation of selection?

b. If there is no dominance at this locus (the fitness of the heterozygote is intermediate to the fitness of the homozygote), what will the allele frequency be after one generation of selection?

c. If Q1 is dominant, what will the allele frequency be after one generation of selection?

Please answer ALL parts of the question and I will be sure to "thumbs up" your answer! Thank you!

Explanation / Answer

Q allele frequency is 0.7. So P allele frequency is 0.3. Q1Q1 has a relative fitness of 0.6. Selection coefficient would be 1-0.6 = 0.4.

a. Frequency of Q1 allele after one generation of selection:

s x q2 x p2 / 1-sp2

= 0.4 x 0.49 x 0.09 / 1- 0.4 x 0.09

= 0.017/0.964

= 0.01

This is the change in frequency.

The frequency of the allele will be 0.7 + 0.01 = 0.71

b. IF there is no dominance and the fitness is equal, then the relative fitness is 1.0. Substituting in the above equation:

s x q2 x p2 / 1-sp2

= 1.0 x 0.49 x 0.09 / 1- 1x 0.09

= 0.044/0.91

= 0.04

The alllele frequency would be 0.7 + 0.04 which will give 0.74.

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c. IF Q1 is dominant, the relative fitness would be more than 0.5 which is 0.6. This gives the same result as subpart a.

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