Question

In Central Africa, the frequency of the sickle-cell allele has remained stable over the years because

the allele protects against malaria. In the United States, malaria was eradicated by eliminating the
mosquito that spreads the disease. The decreasing frequency of the sickle-cell allele in African
Americans since malaria was eliminated in the United States is an example of______

Answer 1

The decreasing frequency of the sickle-cell allele in African Americans since malaria was eliminated in the United States is an example of natural selection.

Step-by-step explanation:

The decreasing frequency of the sickle-cell allele in African Americans since malaria was eliminated in the United States is an example of natural selection.

In regions where malaria is prevalent, individuals with the sickle-cell allele have an advantage as it provides protection against malaria. However, in areas where malaria is rare, such as the United States, carrying the sickle-cell allele does not provide any health benefits. As a result, over time, the frequency of the sickle-cell allele decreases in populations no longer exposed to malaria.

This phenomenon demonstrates how environmental changes can influence the frequency of alleles in a population through natural selection.