Question

Genetics have determined that the majority of individuals in an isolated island population have blood type B. Type A blood is found to be more common in the mainland population from which the island was settled. How could a geneticist best explain the dominance of blood type B in the island population?

Answer 1

Genetic drift reduced the frequency of type A allele

Step-by-step explanation:

Genetic drift can be defined as random fluctuations in the number and frequency of different gene variants (i.e., alleles) in a population due to random sampling. Genetic drift may be caused by founder effects when a small number of individuals becomes isolated from a larger population, thereby leading to the loss of genetic variation. In consequence, genetic drift is predicted to be strong on an isolated island population because the genetic pool of individuals living on the island is generally smaller in diversity compared to the original population due to random chance. In this case, it is expected that genetic drift reduces the frequency of type A individuals.