Question

Which of the following statements are correct about the phenomenon of genetic drift?
A. It occurs in a small population.
B. It leads to the loss of genetic variation within population.
C. It doesn't change the allele frequency randomly.
D. It occurs in a large population.
Choose the most appropriate answer from the options given below:

• A. A and B only
• B. A and C only
• C. B and D only
• D. C and D only

Hint:

Think of genetic drift like flipping a coin. If you flip it 1000 times (large population), you'll get very close to 50% heads. If you only flip it 4 times (small population), it's much more likely you'll get a skewed result like 75% or 100% heads just by chance. That's genetic drift!

Answer 1

The Correct Option is A

Step 1: Understanding the Concept:
Genetic drift is a mechanism of evolution characterized by random fluctuations in the frequencies of alleles in a population's gene pool, primarily due to chance events.

Step 2: Analyzing each statement:
- Statement A: True. The effects of genetic drift are most pronounced in small populations. In a small group, random events (like an individual failing to reproduce by chance) can have a disproportionately large impact on allele frequencies.
- Statement B: True. Genetic drift can lead to the random fixation (frequency of 100%) or loss (frequency of 0%) of alleles. When an allele is lost, genetic variation at that locus is reduced. Over time, drift tends to decrease the genetic diversity within a population.
- Statement C: False. The defining feature of genetic drift is that it changes allele frequencies randomly. Unlike natural selection, which is directional (it selects for adaptive traits), drift is directionless and based purely on chance.
- Statement D: False. While genetic drift technically occurs in any finite population, its effects are negligible and insignificant in large populations. In large populations, random fluctuations tend to cancel each other out, and changes in allele frequency are primarily driven by selection.

Step 3: Final Answer:
Statements A and B are correct descriptions of genetic drift. Statements C and D are incorrect. Therefore, the correct option is (A).