Q.36 Which of the following conditions will contribute to the stability of a gene pool
in a natural population?
P. Large population
Q. No net mutation
R. Non-random mating
S. No selection
(A) P only
(B) P and Q only
(C) P and R only
(D) P, Q and S only
Gene pool stability refers to maintaining constant allele frequencies across generations, as described by the Hardy-Weinberg equilibrium principle. The correct answer is (D) P, Q and S only. This choice aligns with key conditions that prevent evolutionary changes in a population’s genetic makeup.
Correct Answer Breakdown
P. Large population prevents genetic drift, where random events disproportionately alter allele frequencies in small groups. Large populations ensure allele frequencies remain representative and stable over time.
Q. No net mutation eliminates new genetic variations that could shift allele frequencies. Without mutations introducing or removing alleles, the gene pool stays unchanged.
S. No selection means all genotypes have equal reproductive success, avoiding favoritism toward certain traits. Natural selection otherwise drives allele frequency changes by favoring adaptive variants.
Why Not R?
R. Non-random mating disrupts stability through mechanisms like assortative mating or inbreeding, which alter genotype frequencies and can lead to deviations from Hardy-Weinberg predictions. Random mating, the opposite, preserves equilibrium by ensuring alleles combine without bias.
Hardy-Weinberg Conditions Summary
| Condition | Effect on Gene Pool | Matches Option |
|---|---|---|
| Large population | Minimizes drift | P ✓ |
| No net mutation | No new alleles | Q ✓ |
| Random mating | Preserves allele mixing | Opposite of R |
| No migration | Prevents gene flow | Not listed |
| No selection | Equal reproduction | S ✓ |
These factors collectively ensure a natural population’s gene pool remains stable, making evolution negligible under ideal circumstances. Real populations rarely meet all criteria perfectly.
