Which scenario increases the effect of genetic drift?

Which scenario increases the effect of genetic drift?

• A. Small population size
• B. Large population size
• C. High mutation rate
• D. Strong selection pressure

Answer: (A)

Genetic drift is the random fluctuation of allele frequencies from one generation to the next due to sampling in a finite population. The smaller the population, the bigger those random sampling errors become, so allele frequencies can swing widely simply by chance, leading to loss or fixation of alleles more quickly. That’s why a small population amplifies the impact of drift. In a large population, sampling noise is far smaller, so allele frequencies stay relatively stable unless acted on by other forces. A high mutation rate adds new alleles but doesn’t inherently increase the randomness of which alleles get passed on in a given generation. Strong selection, on the other hand, drives changes in allele frequencies in a directed way, which can overshadow random drift.

Genetic drift is the random fluctuation of allele frequencies from one generation to the next due to sampling in a finite population. The smaller the population, the bigger those random sampling errors become, so allele frequencies can swing widely simply by chance, leading to loss or fixation of alleles more quickly. That’s why a small population amplifies the impact of drift.

In a large population, sampling noise is far smaller, so allele frequencies stay relatively stable unless acted on by other forces. A high mutation rate adds new alleles but doesn’t inherently increase the randomness of which alleles get passed on in a given generation. Strong selection, on the other hand, drives changes in allele frequencies in a directed way, which can overshadow random drift.