Question 1

Which mode of natural selection is most likely to occur in a population of deer mice living in an environment where only dark rocks and light sand are present, but no intermediate habitats?

Accepted Answer

Disruptive selection

Question 2

A population of Galápagos finches experiences an increase in the abundance of large seeds. Over time, the average beak depth in the population increases. Which type of selection is responsible for this change?

Accepted Answer

Directional selection

Question 3

In the context of sickle-cell disease, why does the sickle-cell allele remain at relatively high frequencies in regions where malaria is common?

Accepted Answer

Heterozygotes have a selective advantage due to partial protection from malaria

Question 4

Which equation best represents the calculation of relative fitness ($$w) $$for a genotype in a population?

Accepted Answer

$$w = \frac{contribution\;to\;next\;generation}{maximum\;contribution\;by\;any\;genotype}$$

Question 5

Which of the following is NOT a reason why natural selection cannot produce perfect organisms?

Accepted Answer

Natural selection always produces the ideal trait for every environment

Question 6

In frequency-dependent selection, what happens to the fitness of a phenotype as it becomes more common in the population?

Accepted Answer

Its fitness decreases

Question 7

A population of black-bellied seedcracker finches in Cameroon displays two distinct beak sizes, with intermediate-sized beaks being inefficient. Which mode of selection is most likely acting on this population?

Accepted Answer

Disruptive selection

Question 8

Which of the following best describes stabilizing selection?

Accepted Answer

It favors intermediate variants and acts against extreme phenotypes

Question 9

Why is natural selection considered the only mechanism that consistently leads to adaptive evolution?

Accepted Answer

It consistently increases the frequency of alleles that provide reproductive advantage

Question 10

Which real-world example illustrates the concept of adaptation through natural selection?

Accepted Answer

Movable jaw bones in snakes allow them to swallow prey much larger than their head

Question 11

In sexual selection, what is the primary reason that female peahens choose males with showy plumage?

Accepted Answer

Showy plumage is correlated with 'good genes' and overall genetic quality

Question 12

A researcher splits each female frog’s eggs into two batches for fertilization by different males. What is the main advantage of this experimental design?

Accepted Answer

It allows comparison of offspring performance from different male genotypes under identical environmental conditions

Question 13

Which equation describes the Hardy-Weinberg equilibrium for allele frequencies in a population?

Accepted Answer

$$p^2 + 2pq$$ + $$q^2 = 1$

Question 14

Which of the following is an example of balancing selection?

Accepted Answer

Heterozygote advantage in sickle-cell allele in malaria regions

Question 15

In a population where environmental conditions change unpredictably from year to year, which factor is most likely to limit adaptive evolution?

Accepted Answer

Chance events and environmental variability

Question 16

If a population lacks alleles that could delay molting in snowshoe hares, what is the most likely outcome when the first snowfall occurs later in the year due to climate change?

Accepted Answer

Hares will be poorly camouflaged and more vulnerable to predation

Question 17

Which of the following best describes the outcome of disruptive selection?

Accepted Answer

Both extreme phenotypes are favored over intermediates

Question 18

In the scale-eating fish Perissodus microlepis, what is the evolutionary consequence of frequency-dependent selection?

Accepted Answer

The frequency of left- and right-mouthed individuals oscillates over time

Question 19

Which statement about sexual dimorphism is correct?

Accepted Answer

It results from sexual selection and includes differences in size, color, ornamentation, and behavior between males and females

Question 20

Why might a seal’s flippers be considered an adaptation that is a compromise?

Accepted Answer

Flippers allow seals to swim efficiently but make walking on land more difficult

Natural Selection and Adaptive Evolution: Mechanisms and Constraints

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