Suppose that in a population of 90 individuals, the frequency of allele A(p)=0.8

Question

Suppose that in a population of 90 individuals, the frequency of allele A(p)=0.8, and they frequency of allele a(q)=0.2. If 10 individuals with frequency of allele a(q)=0.2 migrate in to this population and are successful in breeding, what is the expected frequency of the a allele (q) after one generation? Answer: .02

If a male drosophila is crossed with a number of females and produces progeny whose wing length averages 18mm whereas the overall population mean 20mm, what is the breeding value of this male? Answer: .4mm

***Looking for explanations of how to arrive at the solutions to these questions, please show work. Thank you.

Explanation / Answer

A 1. From paternal side (sperm) the given proportions of two alleles are 0.8 of allele A and 0.2 of allele a.

2. From maternal side (egg) the given proportion of two alleles are 0.8 of A and 0.2. of a alleles.

3. If 10 individuals with frequency of allele a(q)=0.2 migrate in to this population and are successful in breeding.

4. The probability of an A sperm meeting an A egg is 0.8 x 0.8 = 0.64,

The probability of an A sperm meeting an a egg and vice versa is 0.8 x 0.2 = 0.16

The probability of an a sperm meeting an a egg is 0.2 x0.2 = 0.04

5. There in the following generation, we would expect the following proportions of genotypes: 0.64 AA, 0.32 Aa and 0.04 aa.

6. If there were 100 offsprings there would be 64 AA, 32 Aa and 4 aa individuals.

7. This in turn tranlsates to 160 A allels ( 64+64+32), 160/200 = 0.8

8, And 40 a alleles (32+4+4), 40/200 = 0.2. So the expected frequency of the a allele (q) in the next generation is same of that of parent.

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