Question

Given below are two statements: Statement (I): Change in gene frequencies in erratic manner from generation to generation is called random drift. Statement (II): Random drift may lead to fixation or loss of entire genotypes in a population. In light of the above statements, choose the most appropriate answer from the options given below:

• A. Both Statement (I) and Statement (II) are correct.
• B. Both Statement (I) and Statement (II) are incorrect.
• C. Statement (I) is correct but Statement (II) is incorrect.
• D. Statement (I) is incorrect but Statement (II) is correct.

Hint:

Genetic drift is highly potent in small populations.
It causes random, erratic changes in allele frequencies that eventually result in complete fixation or loss of genetic diversity.

Answer 1

The Correct Option is A

Step 1: Understanding the Concept:
Random genetic drift refers to fluctuations in allele frequencies that occur by chance in finite populations.
Unlike natural selection, genetic drift is non-directional and occurs due to random sampling errors during gamete formation.

Step 2: Detailed Explanation:
Let us evaluate both statements.
- Statement (I) describes the nature of allele frequency changes under genetic drift.
In small or finite populations, the alleles passed to offspring are a random sample of parental alleles.
This random sampling causes allele frequencies to fluctuate up and down unpredictably from one generation to the next.
This non-directional, erratic movement is the defining feature of random drift.
Thus, Statement (I) is correct.
- Statement (II) addresses the long-term effects of genetic drift.
As allele frequencies fluctuate randomly, they eventually hit the boundaries of \( 0 \) (loss) or \( 1 \) (fixation).
When an allele is lost or fixed, the genetic variation at that locus disappears.
This leads directly to the loss of heterozygous genotypes and the fixation of homozygous genotypes.
Thus, Statement (II) is correct.
Therefore, both Statement (I) and Statement (II) are correct.

Step 3: Final Answer:
Both Statement (I) and Statement (II) are correct, corresponding to option 1.