In a random mating population in equilibrium, which of the following brings about a change in gene frequency in a non-directional manner : -
A
Mutations
B
Random drift
C
Selection
D
Migration
The answer is A.
Solution
Factors that disturb Hardy–Weinberg equilibrium are mutation, gene flow (migration), genetic drift, natural selection and non-random mating. Selection changes allele frequencies in a definite direction, favouring the better adapted allele. Recurrent mutation and migration also push frequencies towards particular values. Random genetic drift is the change in allele frequency purely by chance, especially in small populations. The frequency of an allele may go up in one generation and down in the next; its direction cannot be predicted. So random drift brings about a change in gene frequency in a non-directional manner.
ConceptGenetic drift is non-directional
Evolution in past papers
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