Q.1 In a large wild flower population, assume that no new mutations occur and that no natural selection
operates. What factor(s) will affect the frequency of a genotype in this population?
(A) Non-random mating
(B) Gene flow
(C) Out-breeding within the population
(D) Invasion of a new pathogen that kills a large number of individuals in the population

Correct Answer: (A) Non-random mating

In a large wild flower population with no new mutations and no natural selection, genotype frequencies remain stable under Hardy-Weinberg equilibrium only if mating is random and no other forces interfere. Non-random mating disrupts this by altering genotype proportions without changing allele frequencies.

Option Analysis

Non-random mating (A): This violates random mating assumption, causing excess homozygotes through inbreeding or assortative mating, thus changing genotype frequencies.

Gene flow (B): Immigration/emigration introduces alleles from outside, shifting both allele and genotype frequencies in the population.

Out-breeding within the population (C): Promotes random mating by mixing diverse genotypes, maintaining Hardy-Weinberg proportions without altering frequencies.

Invasion of a new pathogen (D): Acts as selection by differentially killing genotypes, violating no-selection condition and changing frequencies.

In population genetics, understanding factors affecting genotype frequency in population no mutation no selection is crucial for CSIR NET Life Sciences aspirants studying Hardy-Weinberg equilibrium. This principle predicts stable genotype frequencies (p², 2pq, q²) in large, randomly mating populations without evolutionary forces.

Hardy-Weinberg Assumptions

Hardy-Weinberg requires infinite population size, random mating, no mutation, no migration, and no selection. Violations like non-random mating increase homozygotes, while gene flow alters allele pools.

• Large population prevents drift.

• Random mating ensures predictable combinations.

• No external alleles via migration.

Detailed Option Breakdown

Non-random mating (inbreeding) skews genotypes toward homozygosity without allele change. Gene flow introduces foreign alleles, disrupting equilibrium. Out-breeding maintains randomness, having no effect. Pathogen invasion imposes selection, killing specific genotypes.

CSIR NET Relevance

These concepts test evolutionary mechanisms in Unit 11. Focus on how non-random mating alone changes genotypes without alleles shifting, key for MCQs on wild flower populations.