How does genetic drift primarily affect small populations?

How does genetic drift primarily affect small populations?

• A. By decreasing gene flow between populations
• B. By causing random changes in allele frequencies
• C. By introducing new mutations more quickly
• D. By stabilizing allele frequencies over time

Answer: (B)

Genetic drift primarily affects small populations by causing random changes in allele frequencies. In small populations, the impact of chance events can be significant because each individual's genetic contribution represents a larger portion of the total gene pool. This randomness can lead to fluctuations in allele frequencies from one generation to the next, which may drastically change the genetic makeup of the population over time. For instance, if a few individuals happen to reproduce more or die out due to random events, their alleles may become more or less common, regardless of their adaptive value. This contrasts with larger populations, where the effects of genetic drift are mitigated due to the larger number of individuals, making chance events less impactful on overall allele frequencies. The other options involve mechanisms that do not specifically illustrate the concept of genetic drift. Decreasing gene flow pertains more to barriers affecting population connectivity and does not detail how allele frequencies change. Introducing new mutations relates to mechanisms of evolution but is not the primary focus of genetic drift. Stabilizing allele frequencies implies that genetic diversity is maintained, which contradicts the effects of genetic drift, where random fluctuations often disrupt this stability.

Genetic drift primarily affects small populations by causing random changes in allele frequencies. In small populations, the impact of chance events can be significant because each individual's genetic contribution represents a larger portion of the total gene pool. This randomness can lead to fluctuations in allele frequencies from one generation to the next, which may drastically change the genetic makeup of the population over time.

For instance, if a few individuals happen to reproduce more or die out due to random events, their alleles may become more or less common, regardless of their adaptive value. This contrasts with larger populations, where the effects of genetic drift are mitigated due to the larger number of individuals, making chance events less impactful on overall allele frequencies.

The other options involve mechanisms that do not specifically illustrate the concept of genetic drift. Decreasing gene flow pertains more to barriers affecting population connectivity and does not detail how allele frequencies change. Introducing new mutations relates to mechanisms of evolution but is not the primary focus of genetic drift. Stabilizing allele frequencies implies that genetic diversity is maintained, which contradicts the effects of genetic drift, where random fluctuations often disrupt this stability.