Question

question 4
a large sample of flies from the population in question 2 is moved to a new habitat. there are no flies existing there. there is a lot more fermenting fruit (and thus alcohol) in this environment compared to the original environment. over 10 generations, the frequency of the fast allele increases from 0.3 to 0.6. what evolutionary force is responsible for this result?
mutation
migration
genetic drift
natural selection
question 5
which evolutionary force is most powerful in small populations?
mutation
migration
genetic drift
natural selection

Explanation:

For Question 4:

• Mutation is a change in DNA sequence. There is no mention of new genetic material being created here.
• Migration would involve movement of individuals into or out of a population, but the scenario is about allele frequency change due to environment - not movement of individuals in that sense (the sample was already moved).
• Genetic drift is random change in allele frequencies, often in small populations. Here, the change is likely due to the environment (more fermenting fruit/alcohol) favoring the fast allele.
• Natural selection occurs when certain traits (alleles) are favored due to environmental conditions. The increase in the fast - allele frequency over generations in an environment with more fermenting fruit (where the fast allele may be advantageous for processing alcohol) is a case of natural selection.

For Question 5:

• Mutation is a slow process and not the most powerful in small populations.
• Migration is about movement of individuals, not the most relevant for small - population allele - frequency changes in general.
• Genetic drift has a more pronounced effect in small populations. Random fluctuations in allele frequencies (e.g., due to chance events like which individuals reproduce) can have a big impact when the population size is small.
• Natural selection acts based on fitness, but in small populations, random events (genetic drift) often have a more immediate and powerful effect.

Answer:

Question 4: natural selection
Question 5: genetic drift