Q2CC - Campbell Biology

Question

The gene that causes sickle cell disease is present in a higher percentage of residents of Sub-Saharan Africa than among those of African descent living in the United States. Even though this gene causes sickle cell disease, it protects from malaria, a severe illness widespread in Sub-Saharan Africa but absent in the United States. Discuss an evolutionary process that could account for the different percentages of the sickle cell gene among residents of the two regions.

Step-by-Step Solution

Answer

Certain types of evolutionary adaptations take place over some time. The sickle cell gene offers resistance to malaria in the Sub-Saharan population compared to the Africans in the United States. It is due to the natural selection mechanism.

Evolutionary aspects of Sub-Saharan African population staying in the same region

The region of Sub-Saharan Africa commonly has the disease of malaria. The sickle cell anemia gene is present in the residents of Sub-Saharan Africa.

 

The condition of sickle cell anemia arises due to the mutation of beta globulin. The sickle cell gene offers some resistance to malaria because the gene is in heterozygous form. It is an essential advantage for this population to show some resistance to this disease. It also gets transferred to future generations.

Evolutionary aspects of African population staying in the United States

The people who belong to the Sub-Saharan African population reside in the Saharan desert region. The descendants of the African population who migrated and settled in the US are referred to as the African population.

 

The sickle cell anemia gene is absent in the population staying in the United States. It reduces the transmission of the sickle cell anemia gene to future generations. It can increase the possibility of the occurrence of malaria disease in individuals. 

 

The absence of the sickle cell gene is due to the lack of a selection mechanism. If the particular gene is not inherited, this can result in increasing the risk of malaria.

Evolutionary mechanism

The essential primary mechanism associated with the hereditability of the sickle cell anemia gene is natural selection. This mechanism of natural selection led to a different percentage of sickle cell genes via the difference in inheritance patterns.

 

The selection acts as a pressure for the inheritance of this gene which can result in other populations. It is a natural phenomenon that can select particular species to develop adaptation associated with specific heritable changes.

 

Hence, comparing both populations, the descendants staying in Africa have increased resistance to malaria due to inheriting the sickle cell anemia gene as compared to the descendants staying in the United States.