Question

Compare and contrast the expected changes in allele frequency in a population depending on whether that allele is under selection vs. experiencing genetic drift.

A) Alleles under selection tend to increase in frequency, while alleles experiencing drift change randomly.
B) Alleles under selection and experiencing drift both change randomly.
C) Alleles under selection tend to decrease in frequency, while alleles experiencing drift remain stable.
D) Alleles under selection and alleles experiencing drift both tend to increase in frequency.

Answer 1

The correct comparison is that alleles under natural selection tend to increase in frequency if they are advantageous, whereas genetic drift involves random changes in allele frequencies that are not tied to any selective advantage.

Step-by-step explanation:

When comparing changes in allele frequency due to selection versus genetic drift, the correct answer is A) Alleles under selection tend to increase in frequency, while alleles experiencing drift change randomly.

Natural selection can cause alleles that provide a reproductive advantage to become more common over time. Conversely, genetic drift refers to random changes in allele frequencies, typically in small populations, that occur without any advantage being conferred by the alleles themselves. This randomness can lead to some alleles becoming more common or even being lost from the gene pool simply due to chance events. An extreme case of genetic drift can be seen through the founder effect when a small group establishes a new population with different allele frequencies than the original population. While natural selection and genetic drift can both lead to changes in a population’s genome, they operate through distinct mechanisms, and their effects on allele frequencies differ considerably.