Genetic drift
Genetic drift
It is an example of Natural Selection, Modern Theories of Evolution.
People with sickle cell disease, or who carry sickle cell trait, are said to be resistant to malaria.
Malaria is common in topical ad subtropical zones. The malaria has selected the people with sickle cell anaemia. Although person with sickle cell anemia can have malaria, the carrier, or the person with sickle cell trait is resistant to malaria.
Sickle cell is common in people from tropical areas where malaria is prevalent. Malaria can not survive on blood cells that are sickle shaped, so when populations were being killed off by malaria, those with sickle cell were surviving and passing on the sickle cell gene.
No they are generally resistant to malaria
Since people with the sickle cell allele trait are resistent to malaria, if malaria were eliminated there would be no change in the frequncy of sickle cell allele. This is because the presense of malaria does not have an affect on patients with the sickle cell allele trait.
the sickle trait possess a resistance to the infection of malaria.
People with a sickle-cell gene are resistant, but not immune, to malaria. African people, who were greatly exposed to malaria, were more likely to survive malaria with sickle-cell genes, so the survivors passed it on to their children. Not all African people have sickle-cell genes.
Not sure if this is right but could it be because the blood cell does not contain enough oxygen for the parasite to survive?
No, hemophilia does not confer an advantage against malaria. People with sickle-cell anemia do have an immunity, of sorts.
It is more common for people of African descent to get sickle cell anemia. Sickle cell anemia is linked to survivors of falciparum malaria (P. falciparum), it is believed that the hemoglobin cells take on the sickle shape to give the mammal an increased survival rate.