Review Questions

3.1. The following data show the number of individuals in a population of Drosophila polymorpha that had the three alternative abdomen colour genotypes (after Cunha, 1949):

EE (dark): 3969 Ee (intermediate): 3174 ee (light): 927

(i) Calculate the frequency of each allele.

(ii) Calculate the genotype frequencies that would be expected if this population was in Hardy-Weinberg equilibrium.

(iii) Calculate the number of individuals of each genotype that would be expected if this population was in Hardy-Weinberg equilibrium.

(iv) Calculate the value for a comparison between observed and expected genotype frequencies.

3.2. Tawny owls (Strix aluco) produce more females in their broods when vole densities are high. Uneven sex ratios meant that Population 1 consisted of 41 breeding males and 68 breeding females, whereas Population 2, which was of the same size, had a more even sex ratio of 52 breeding males and 57 breeding females. Assuming that both populations consist entirely of breeding adults, calculate the Ne/ Nc ratio in these two populations.

3.3. A population goes through a bottleneck, and as a result its effective population size over six generations is 104, 104, 104, 103, 104 and 104.

(i) Calculate this population's long-term effective population size.

(ii) Calculate the current Ne/Nc ratio.

3.4. In a small population of medium ground finches consisting of ten males and ten females, what is the rate at which genetic diversity would be lost each generation following genetic drift (assuming that population size remains constant) from:

(i) the nuclear genome?

(ii) the mitochondrial genome?

3.5. Provide five possible explanations why the Ho of a population can be significantly lower than its He.

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