Genetics This is about a squirrel population at RSU reserve. The population dist

Question

Genetics This is about a squirrel population at RSU reserve. The population distribution among squirrel genotypes were 490 (AA: dark colored), 420 (Aa: gray colored), and 90 (aa: light colored). The survival rates until reproductive age of AA, AB, and aa genotype are 40% 80% and 60% respectively (1) What are the genotypic frequencies of AA, Aa, and aa? (2) What arc the allele frequencies of A and a (3) What are the relative fitness values of the three genotypes? (4) Explain the meaning of relative fitness value of Aa in relation to AA and aa. (5) What is the mean fitness value of the population? 6) What would be the genotypic frequencies of AA, Aa, and aa after one generation?

Explanation / Answer

The population distribution in squirrel genotypes were,

490 (AA; dark colred)

420 (Aa; grey colored) and

90 (aa; light colred)

The survival rates of these genotypes were 40%, 80% and 60% respectively.

1) The genotype frequencies are,

AA = 490 / (490 + 420 + 90 ) = 490/1000 = 0.49

Aa = 420 / (490 + 420 + 90) = 420/1000 = 0.42

aa = 90 / (490 + 420 + 90) = 90/1000 = 0.09

2) The allele frequencies are calculated as follows,

A = (490 + (420/2)) / 1000 = (490 + 210) / 1000 = 700/1000 = 0.7

a = (90 + (420/2)) / 1000 = (90 + 210) / 1000 = 300/1000 = 0.3

3) The relative fitness of genotypes is the survival rate of that particular genotype in relation to the maximum survival rate. So, the relative fitness of the genotypes are calculated as follows,

AA = 40/80 = 0.5

Aa = 80/80 = 1

aa = 60/80 = 0.75

4) Aa genotype has the maximum relative fitness value of 1 when compared to that of genotypes AA and aa that have the relative fitness values of 0.5 and 0.75 respectively.

5) The mean fitness of the population is the is the sum of the fitnesses of the genotypes multiplied by the frequency at which they occur. It is calculated as follows.

= 0.5 (0.49) + 1 (0.42) + 0.75 (0.09)

= 0.245 + 0.42 + 0.0675

= 0.7325

6) The genotypic frequencies in the next generation is as follows,

AA = p^2 / W mean = (0.7)(0.7) / 0.7325 = 0.669

Aa = 2pq / W mean = 2 (0.7)(0.3) / 0.7325 = 0.573

aa = q^2 ? W mean = (0.3)(0.3) / 0.7325 = 0.123

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