Question

a population has a small size, high level of genetic drift, and very little migration into the population. what will most likely happen to the genetic diversity in the population over time?

genetic diversity will decrease because existing alleles will be lost and few new alleles will be introduced.
genetic diversity will increase because the existing alleles will mutate into new alleles.
genetic diversity will remain unchanged because high levels of genetic drift offset low levels of gene flow.
genetic diversity will remain unchanged because genetic drift does not have much of an impact on small populations.

Explanation:

Analyze the effects of small population size and genetic drift

Using the Genetic Diversity knowledge point

• Small population size increases the impact of random fluctuations in allele frequencies.
• Over time, random genetic drift leads to the fixation of some alleles and the complete loss of others.
• This process significantly reduces the overall variation within the gene pool.

Analyze the effect of low migration

Using the Mechanisms of Evolution knowledge point

• Migration (gene flow) is a primary source of introducing new alleles into a population.
• Very little migration means that lost alleles are not being replaced by incoming individuals.
• Consequently, the lack of gene flow prevents the recovery of variation, leading to a net decrease in diversity.

Evaluate the given options

• Option 1 correctly states that diversity will decrease due to the loss of existing alleles from drift and the lack of new alleles from low migration.
• Option 2 is incorrect because mutation rates are generally low and do not automatically increase to compensate for drift.
• Option 3 is incorrect because genetic drift and low gene flow both act to reduce or limit diversity, rather than offsetting each other.
• Option 4 is incorrect because genetic drift has a massive impact on small populations.

Answer:

• (A) Genetic diversity will decrease because existing alleles will be lost and few new alleles will be introduced. (Correct answer)
• (B) Genetic diversity will increase because the existing alleles will mutate into new alleles.
• (C) Genetic diversity will remain unchanged because high levels of genetic drift offset low levels of gene flow.
• (D) Genetic diversity will remain unchanged because genetic drift does not have much of an impact on small populations.