The following statements describe change in allele frequencies over time:

A. Fixation of an allele is purely by chance, while other alleles are lost.
B. Genetic drift can lead to the loss of certain alleles over time, reducing genetic diversity within the population.
C. Changes in allele frequencies are due to positive selection.
D. There is a pronounced effect in small populations, where random events can drastically alter allele frequencies.

Which one of the following options represents the combination of all correct statements if allele frequencies change purely due to genetic drift?

Correct option is B

Sol.

• A is correct: Fixation or loss of alleles by genetic drift occurs randomly by chance, not by selection.

• B is correct: Genetic drift can cause certain alleles to be lost over time, leading to reduced genetic diversity.

• C is incorrect: Changes due to positive selection are not genetic drift but natural selection.

• D is correct: Genetic drift has a stronger effect in small populations where random events can significantly change allele frequencies.

Information Booster:

• Genetic drift is a stochastic process that alters allele frequencies independently of fitness.

• It can lead to fixation or loss of alleles, especially in small populations.

• Unlike selection, drift is random and does not favor advantageous alleles.