During class, I outlined the changes in the frequency of hemoglobin A (HbA) and

Question

During class, I outlined the changes in the frequency of hemoglobin A (HbA) and hemoglobin S (Hbs) alleles in a west African village with a breeding population of 50 (25 couples) over three generations. For this exercise, I will use the symbol a for Hba alleles and & S for Hbs alleles. During that period, malaria became prevalent and killed a large proportion of the children born who had the genotype AA and were thus unprotected from malaria. During the same period, homozygous individuals (genotype AS) became much more common in the population. In another, similar village (breeding population of 50) where malarias was also killing large numbers of children, a slightly different pattern emerged over 4 generations. Calculate the gene frequencies of each of the two alleles, A and S, for the following four generations (G1 - G4). During that period, no SS individuals lived long enough to reproduce. After UNESCO eradicated the malaria mosquito from the village area during generation Gen 4. no villagers succumbed to malaria. AA individuals also had a slight advantage over heterozygous (AS) individuals because their blood worked better during heavy exertion. The following pattern occurred during the next five generations. Using the numbers provided, calculate the frequencies of A and S alleles in the village population for generations G5-G9. Comment on the evolutionary changes (changes in gene frequency, population size, etc.) that occurred in this village over the 9 generations represented on the chart.

Explanation / Answer

Answer:

If the static population, the frequency of recessive allele was increased. If the population is increased, the frequency of recessive allele was decreased.

Population AA As freq A freq S Gene 1      50 48 2 0.8 0.2 Gene 2      50 40 10 0.55 0.45 Gene 3      50 33 17 0.42 0.58 Gene 4      50 26 24 0.31 0.69

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