Volpe's Understanding Evolution 7th Edition by Peter Rosenbaum

Exercise 5

Natural selection confers an advantage to certain alleles under specific environmental conditions. Based on this notion, what accounts for the relatively high frequency of the gene for sickle cell anemia in people from tropical Africa?
A) Affect persons survive under tropical conditions whereas they do not in temperate conditions.
B) Various parasites infect people without sickle cell genes in tropical Africa.
C) Persons with a single copy of the sickle cell gene are not attractive to the mosquito that transmits malaria.
D) Persons with single copy of the sickle cell gene are less susceptible to malaria than those with normal hemoglobin genes.
E) Persons with two copies of the sickle cell gene are less susceptible to malaria than those with one copy or no copies of this gene.