Question

In the United States, the parasite that causes malaria is not present, but it is present in African-Americans whose ancestors were from equatorial Africa. What should be happening to the sickle-cell allele in the United States, and what should be happening to it in equatorial Africa?

Answer 1

Answer: DIRECTIONAL SELECTION; STABILIZING SELECTION.

Explanation: In the United States of America the parasite that causes Malaria is not present,the parasite that causes Malaria are known to be a protozoa of the Plasmodium specie(Plasmodium: P. falciparum, P. malariae, P. ovale and P. vivax.).

DIRECTIONAL SELECTION is also known as positive selection where an advantageous allele increases as a consequence of differences in survival rate and reproduction among different phenotype Population.

STABILISING SELECTION is a type of natural selection in which a trait tend to remain stable,no one trait is felt more.