Sickle-Cell Anemia

Mutations are the building blocks of species evolution, without which homo sapiens would never have existed. Mutations appear randomly in individuals of every species and can be harmful, beneficial, or have no change on the individual’s ability to survive and reproduce. Harmful mutations can cause the organism to fail at reproducing which deletes that mutation from the population’s gene pool. Beneficial mutations have the opposite effect, resulting in a higher frequency of the specific mutation in future populations. Mutations accumulate in species over time until they amass into a distinctly new species.

Natural Selection is the process proposed by Sir Charles Darwin in which beneficial mutations are ‘selected for’ within a certain environment. The particular mutation builds up within a species allowing them to …show more content…
When these two different gene pools mate over generations, alleles are transferred between them and the gene pool of the population is then altered.

Genetic Drift has to do with evolution within a single population over time. It occurs when random factors affect certain allelic frequencies in a population’s offspring. These random factors could just be chance/happenstance; however the result is a varied generation from the one before it.

B. Why is the incidence of sickle-cell anemia an excellent example of a "balanced polymorphism," in which two or more alleles are maintained by natural selection in a population?

Balanced polymorphism is the term given to the phenomenon where two different versions of a gene are allowed to coexist in an environment. Sickle cell anemia is a great example of balanced polymorphism in action because when a host with a gene for normal hemoglobin and a gene for sickle hemoglobin is infected with a disease like malaria, he has a better chance of surviving than an individual with two genes for normal hemoglobin (Harvard