A deleterious recessive allele is one that can be harmful when it is found in its homgous condition, resulting in a poorly fit phenotype. An example of this is the allelefor sickle cell, which results in the condition known as sickle cell anemia when both recessive alleles are inherited. owever, in regions of Afriche proportion of the sickle cell allele is igher than expected, with as much as 15% of the alleles in the population being the recessive, deleteriou rsion. In the African population, there is also a high prevalence of malaria, a disease caused by the parasitic infestation of a plasmodium protozoan in the blood of humans. The recessive allele for sickle cell has been maintained over many generations. Evaluate the graph above and select the claim that supports the high frequency of the recessive allele in these African populations.
A)There is a selective advantage to the aa genotype, as the presence of sickle cell provides a greater fitness in an environment where malaria is common.
B)There is a selective pressure against the aa genotype, but the presence of malaria induces new mutations which generates more alleles within the population.
C)There is directional selection towards the Aa genotype, since aa is often a lethal condition. Non-random mating tends to maintain the recessive allele in the population.
D)There is a selective advantage to the heterozygous (Aa) condition as there is selective pressure against both the AA and aa genotypes. This maintains the recessive allele in the population.