Final answer:
The Rh- phenotype is found at its lowest frequencies among peoples of European ancestry. This mutation may have been selected for due to exposure to diseases like the plague and smallpox and may provide protection against these diseases. Individuals with the Rh- phenotype may also have a reduced susceptibility to HIV infection.
Step-by-step explanation:
The Rh- phenotype refers to individuals who lack the Rh D antigen on their red blood cells, making them Rh negative. This blood type is found at its lowest frequencies among peoples of European ancestry. It is believed that the mutation leading to the Rh- phenotype has been present in European populations for a long time and may have been selected for due to exposure to diseases like the plague and smallpox. The mutation may provide protection against these diseases. Additionally, recent studies have shown that individuals with the Rh- phenotype may have a reduced susceptibility to HIV infection.