Question

Which of the following factors can NOT cause a population to deviate from Hardy-Weinberg equilibrium ?

• A. Genetic drift
• B. Gene flow
• C. Mutations
• D. Sexual reproduction

Hint:

Think of the gene pool as a deck of cards:
- Sexual reproduction (random mating) is like shuffling the deck; it changes the order of the cards (genotypes) but does not change the total number of each card (allele frequencies).
- Genetic drift, gene flow, and mutation are like adding, removing, or changing the cards in the deck, altering the overall composition.

Answer 1

The Correct Option is D

Step 1: Understanding the Concept:
The Hardy-Weinberg equilibrium principle states that allele and genotype frequencies in a population will remain constant from generation to generation in the absence of evolutionary forces.
A population in Hardy-Weinberg equilibrium assumes a large population size, random mating, no mutation, no natural selection, and no gene flow.

Step 2: Detailed Explanation:
Let us analyze the impact of each factor on allele frequencies in a population:
1. Genetic drift:
This is the random fluctuation of allele frequencies due to chance events in small populations.
It can cause alleles to become fixed or lost over time, leading to a deviation from Hardy-Weinberg equilibrium.
Thus, Option (A) is incorrect.
2. Gene flow (migration):
This is the movement of alleles in or out of a population due to the migration of individuals.
It alters the existing gene pool, leading to a deviation from equilibrium.
Thus, Option (B) is incorrect.
3. Mutations:
This is the spontaneous creation of new alleles, which alters the existing allele frequencies and introduces new genetic variation, leading to a deviation from equilibrium.
Thus, Option (C) is incorrect.
4. Sexual reproduction (under random mating):
Random sexual reproduction simply reshuffles existing maternal and paternal alleles into new combinations in each generation.
By itself, random mating and recombination do not alter the overall allele frequencies in the gene pool; they maintain the equilibrium established in previous generations.
Therefore, random sexual reproduction does not cause a population to deviate from Hardy-Weinberg equilibrium.

Step 3: Final Answer:
Random sexual reproduction does not cause a population to deviate from Hardy-Weinberg equilibrium.
This corresponds to Option (D).