Genetic Drift and Allele Frequency — NEET Biology
✅ Asked in NEET 2021The factor that leads to Founder effect in a population is: (NEET 2021)
The factor that leads to Founder effect in a population is: (NEET 2021)
Genetic drift operates in: (NEET 2016)
Answer & NCERT explanation
Correct answer: A — Genetic drift
Founder effect is caused by genetic drift when a small group establishes a new population. According to NCERT, when few individuals migrate to new area, they carry limited genetic diversity, causing random changes in allele frequencies. This is a specific type of genetic drift, not natural selection or mutation which work differently.
Read more NCERT concept on the PYQ
Five factors are known to affect Hardy-Weinberg equilibrium. These are gene migration or gene flow, genetic drift, mutation, genetic recombination and natural selection. When migration of a section of population to another place and population occurs, gene frequencies change in the original as well as in the new population. New genes/alleles are added to the new population and these are lost from the old population. There would be a gene flow if this gene migration, happens multiple times. If the same change occurs by chance, it is called genetic drift. Sometimes the change in allele frequency is so different in the new sample of population that they become a different species. The original drifted population becomes founders and the effect is called founder effect.
Genetic drift is random change in allele frequency occurring by chance, especially in small populations—it's different from migration (gene flow) which is directional. Students confuse drift with selection; remember drift is chance-based while selection is non-random. NEET asks whether a population change happened due to drift or migration: if alleles change randomly without environmental pressure, it's drift; if new alleles enter from outside, it's gene flow. The founder effect exemplifies drift—when a small group establishes a new population, allele frequencies differ drastically by chance alone. Key distinction: drift causes random change, migration adds specific alleles, selection favors beneficial alleles.
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