Question

Assertion (A) : Genetic drift always increases genetic diversity in small populations.
Reason (R) : Founder effect and Bottleneck effect exemplify the genetic drift.
Identify the correct option from the following

• (A) and (R) are true. (R) is correct explanation for (A).
• (A) and (R) are true. But R is not correct explanation for (A).
• (A) is true, but (R) is false.
• (A) is false, but (R) is true.

Hint:

Genetic drift is a random process, especially impactful in small populations, and typically leads to a loss of genetic diversity. Founder and Bottleneck effects are classic examples of how genetic drift operates.

Answer 1

The Correct Option is D

Step 1: Analyze Assertion (A)

Assertion (A) states: “Genetic drift always increases genetic diversity in small populations.”
Genetic drift is a random change in allele frequencies in a population. In small populations, genetic drift has a more pronounced effect. It typically leads to a decrease in genetic diversity over time, as some alleles may become fixed (reach 100% frequency) and others may be lost entirely, purely by chance.
It does not always increase genetic diversity; in fact, its common effect is the opposite.
Therefore, Assertion (A) is False.

Step 2: Analyze Reason (R)

Reason (R) states: “Founder effect and Bottleneck effect exemplify the genetic drift.”
The Founder effect occurs when a new population is established by a small number of individuals, whose gene pool may not accurately represent the original population’s diversity. The Bottleneck effect occurs when a population undergoes a drastic reduction in size, often due to a catastrophic event, leading to a significant loss of genetic variation.
Both phenomena are specific examples where genetic drift plays a major role in altering allele frequencies and reducing genetic diversity.
Therefore, Reason (R) is True.

Step 3: Evaluate the relationship between (A) and (R)

Since Assertion (A) is false, there is no need to evaluate if Reason (R) is a correct explanation for (A). However, we have established the truthfulness of each statement independently.

Step 4: Conclude the correct option

Based on the analysis, Assertion (A) is false, and Reason (R) is true.
The final answer is: (A) is false, but (R) is true.