Question continuation;
..........type B. Type A 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?
Multiple choices;
A. Random mutations have occurred in the island population.
B. Genetic drift has reduced the frequency of type A individuals.
C. Natural selection has only occurred in the mainland population.
D. Environmental conditions on the island are less favorable for type B individuals.
Answer;
B. Genetic drift has reduced the frequency of type A individuals.
Explanation;
-Genetic drift is a mechanism of evolution in which allele frequencies of a population change over generations due to chance.
-It occurs in all populations of non-infinite size, but its effects are strongest in small populations.
Natural selection is the process that result in the adaptation of an organism to environment by means of selectively reproducing changes in its genotype, or genetic constitution. It is the a key mechanism of evolution. Charles Darwin popularised the term "natural selection" contrasting it with artificial selection, which is intentional, whereas natural selection is not.
To make it simple, let's have a group of beetle composing of green and some are brown as an example. here, there is a variation in traits. Since the environment could not support continuous population growth, not all species can reproduce to their full potential. Green beetles can easily be eaten by other species like birds compared to brown beetles. The surviving brown beetles will then generate brown offsprings because their trait has a genetic basis. Since more brown beetles survive and becomes more common in the population, the process continues until all individuals will eventually be brown. so basically, if you have variation, differential reproduction, and heredity, you will have evolution by natural selection as an outcome.
