Genetic drift operates only in [CBSE PMT 1998]
A) Island populations
B) Smaller populations
C) Larger populations
D) Mendelian populations
Answers
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Correct Answer: B) Small Populations
Reason:
Genetic drift is a random change in gene frequency from one generation to another in a population.
Genetic drift and alleles
Genetic variation in a population can be caused by many factors. The stochastic changes in allele frequency as a result of a small or finite population size is “Genetic Drift”.
Genetic drift occurs in small populations mainly. The reason is occasional occurrences of alleles getting lost with higher probability. If and when this loss of alleles starts then the genetic drift continues until that specific allele is totally lost in the entire population. It is also possible that only one allele remains present at a gene locus within that population.
Large populations and even distributions of allele frequencies among the populations are helpful in maintaining the generic distribution. Genetic drift will be less. Alleles do not become fixed quickly. Genetic drift occurs with alleles with low frequency.
In Island populations the genes continue to descend and are usually not lost.