Question

B. Evolution:

i) Why is sickle-cell anemia so prevalent in west-central Africa? Explain this in terms of natural selection—what phenotype is being selected for?

ii) What genotype is increasing?

iii) What does that mean for the population (e.g. why does sickle-cell anemia remain in the population)?

Answer 1

B)

1) the Sickle Cell anaemia is prevalent in the West Central Africa. Because there is found heterozygote advantage in the West African population. In case of heterozygous condition, there is found normal red blood cell as well as the Sickle Cell red blood cell. The Sickle Cell shaped red blood cell do not allow malaria pathogen to infect it. That's why the individual having heterozygous condition will favour in the West African population.The phenotype has both kind of red blood cells.

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2) the heterozygous genotype is increasing in this population. Because of heterozygote advantage.

3) the Sickle Cell trait reducing the capacity of red blood cell to carry out the oxygen to the different part of the body. Yet it is increasing in the population because the Sickle Cell trait allowed the individual for surviving in the presence of malaria pathogen. Because the Malaria pathogen cannot complete its life cycle in the presence of Sickle Cell trait bearing red blood cells.