Question 1

Which of the following best describes the modern, formal definition of natural selection?

Accepted Answer

A process where individuals with genotypes that promote survival in the current environment disproportionately survive to reproduce, causing a change in genotype frequencies over generations.

Question 2

In the context of selection in diploid organisms, what does 'relative fitness' ($$\omega) $$represent?

Accepted Answer

The fitness of a genotype scaled relative to the genotype with the highest fitness, which is set to 1.

Question 3

Given a population in Hardy-Weinberg equilibrium with allele frequencies $$p$$ and $$q$$ for alleles A and a, respectively, and relative fitness values $$\omega_{11}$$, $$\omega_{12}$$, and $$\omega_{22}$$ for genotypes AA, Aa, and aa, what is the formula for the average fitness ($$\omega) of $$the population?

Accepted Answer

$$\omega = p^2$ \omega_{11} + 2pq \omega_{12} + q^2$ \omega_{22}$$

Question 4

After selection, how is the new frequency of allele A ($$p') $$calculated in a diploid population?

Accepted Answer

$$p' = \frac{p^2$ \omega_{11} + pq \omega_{12}}{\omega}$$

Question 5

Which of the following statements about the effect of selection on genotype frequencies is correct?

Accepted Answer

After selection, the sum of genotype frequencies is less than 1 before normalization.

Question 6

If the relative fitness values for genotypes are $$\omega_{11} = 0.95$$, $$\omega_{12} = 0.99$$, and $$\omega_{22} = 1.0$$, and the initial frequency of allele A is $$p_0 = 0.99$, what will happen to the frequency of allele A over time?

Accepted Answer

The frequency of allele A will decrease over generations.

Question 7

Which equation correctly expresses the change in allele frequency ($$\Delta p) $$due to selection in a diploid population?

Accepted Answer

$$\Delta p = pq \frac{p(\omega_{11} - \omega_{12}) + q(\omega_{12} - \omega_{22})}{\omega}$$

Question 8

In a population of 50 individuals, the frequency of allele A is 0.7. What is the probability that this allele will eventually be lost due to random genetic drift?

Accepted Answer

0.3

Question 9

Which of the following best describes random genetic drift?

Accepted Answer

A change in allele frequency over generations due to sampling processes.

Question 10

In a real-world scenario, a population of insects is exposed to a new pesticide. Some individuals have a genotype that confers resistance, with $$\omega_{RR} = 1.0$$, $$\omega_{Rr} = 0.8$$, and $$\omega_{rr} = 0.5. If $$the initial frequency of the resistance allele (R) is low, what is the most likely outcome over several generations?

Accepted Answer

The frequency of the resistance allele (R) will increase due to selection.

Question 11

If a genotype's relative fitness ($$\omega_{xy}) is $$less than 1, what does this indicate about its survivorship compared to the genotype with $$\omega = 1$$?

Accepted Answer

It has a lower probability of surviving to reproductive age.

Question 12

A population of smoodges has $$p = 0.5$$ for allele A, $$\omega_{11} = 0.9$$, and $$\omega_{12} = 0.95. $$What is the frequency of allele A after two generations, according to the example in the study materials?

Accepted Answer

0.474

Question 13

Which of the following is NOT a requirement for natural selection to cause a change in genotype frequencies in a population?

Accepted Answer

All individuals must have identical genotypes.

Question 14

In the context of Hardy-Weinberg equilibrium and selection, what is the effect of normalizing post-selection genotype frequencies by dividing by average fitness ($$\omega$$)?

Accepted Answer

It ensures that the sum of genotype frequencies equals 1.

Question 15

Which of the following best explains why the sum of genotype frequencies is less than 1 immediately after selection but before normalization?

Accepted Answer

Some individuals do not survive to reproduce, reducing the total number of individuals.

Question 16

If the relative fitness values for genotypes are $$\omega_{11} = 1.0$$, $$\omega_{12} = 0.8$$, and $$\omega_{22} = 0.6$$, which genotype is expected to increase in frequency over time?

Accepted Answer

AA

Question 17

Which of the following is a correct interpretation of the coefficient $$\omega_{12} in $$population genetics models?

Accepted Answer

It is the relative fitness of the heterozygote genotype (Aa).

Question 18

In a population under selection, which genotype contributes half of its frequency to the new frequency of allele A in the next generation?

Accepted Answer

Aa

Question 19

Which of the following scenarios would most likely lead to a rapid change in allele frequency due to selection?

Accepted Answer

A large difference in relative fitness between genotypes.

Hardy-Weinberg Equilibrium and Selection: Mathematical Models in Population Genetics

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