Question

Why are small populations more prone to variations in allele frequency from generation to generation as a result of genetic drift than are large populations?

Short answer

Answer: Small populations are more prone to variations in allele frequency due to genetic drift because random events, such as an individual carrying a specific allele dying without reproducing or producing more offspring, can significantly alter the frequency of alleles within these smaller populations. In contrast, large populations have more individuals carrying various alleles, making it less likely for random events to dramatically shift the frequency of any given allele and leading to more stable allele frequencies across generations.

Step-by-step solution

Understanding Genetic Drift

Genetic drift is a random change in allele frequencies within a population due to chance events. In each generation, some alleles are passed down more frequently to the offspring, while others are passed down less frequently. Over time, this can lead to changes in the frequency of alleles within the population, which in turn may result in the loss or fixation of certain alleles.

Effects of Population Size on Genetic Drift

Now, let's consider the effect of population size on genetic drift. In small populations, the number of individuals carrying a particular allele is also small. As a result, random events may significantly alter the frequency of alleles in such populations. For example, if an individual carrying a specific allele dies without reproducing or an individual with a unique allele produces more offspring, the frequency of alleles within that population may shift dramatically.

Genetic Drift in Large Populations

In contrast, large populations have a greater number of individuals carrying various alleles. Therefore, it is less likely for random events to dramatically shift the frequency of any given allele. Even if an individual with a unique allele dies or produces more offspring, the overall effect on the allele frequency in a large population will be minimal. Thus, genetic drift tends to have a lesser impact on large populations, leading to more stable allele frequencies across generations.

Conclusion

In conclusion, small populations are more prone to variations in allele frequency from generation to generation as a result of genetic drift because random events can have a more significant impact on the frequencies within these populations. On the other hand, large populations are less affected by genetic drift as random events have a minimal impact on the overall allele frequency.