CLEP Biology Mechanisms of Natural Selection 3 — Questions and Answers
Question 1: Sexual selection differs from natural selection primarily because it:
- Acts only on females
- Involves competition for mates rather than survival (Correct answer)
- Increases genetic diversity in all cases
- Only occurs in mammals
Correct answer: Involves competition for mates rather than survival
Sexual selection specifically involves differential reproductive success based on mate competition or mate choice, not merely survival.
Question 2: The concept of 'fitness' in evolutionary biology specifically refers to:
- An organism's physical strength
- The ability to survive extreme environments
- Reproductive success relative to other individuals (Correct answer)
- An organism's lifespan
Correct answer: Reproductive success relative to other individuals
Evolutionary fitness is defined as an individual's ability to survive and reproduce relative to others in the population.
Question 3: Which scenario illustrates the founder effect?
- A hurricane kills 90% of a bird population
- A few birds colonize a distant island and establish a new population (Correct answer)
- Two bird populations merge due to habitat destruction
- A bird population splits as a mountain range forms
Correct answer: A few birds colonize a distant island and establish a new population
The founder effect occurs when a small group establishes a new population, carrying only a subset of the original genetic variation.
Question 4: Heterozygote advantage (overdominance) maintains two alleles in a population because:
- Mutation rates for both alleles are equal
- Heterozygotes have higher fitness than either homozygote (Correct answer)
- The alleles are on different chromosomes
- Natural selection is absent in that population
Correct answer: Heterozygotes have higher fitness than either homozygote
When heterozygotes are more fit than either homozygote, both alleles are preserved through balancing selection.
Question 5: Which of the following would INCREASE the rate of evolution by natural selection?
- Asexual reproduction only
- Low mutation rates
- High heritability of traits (Correct answer)
- Constant environmental conditions
Correct answer: High heritability of traits
High heritability means traits are strongly passed from parent to offspring, making natural selection more effective at changing allele frequencies.
Question 6: Random genetic drift has the greatest effect on allele frequencies in:
- Large populations with high gene flow
- Small, isolated populations (Correct answer)
- Populations with high mutation rates
- Sexually reproducing populations only
Correct answer: Small, isolated populations
Genetic drift is a random process whose effects are amplified in small populations where chance events significantly alter allele frequencies.
Question 7: Mimicry in which a harmless species resembles a dangerous one to deter predators is called:
- Müllerian mimicry
- Batesian mimicry (Correct answer)
- Cryptic coloration
- Aposematism
Correct answer: Batesian mimicry
Batesian mimicry occurs when a palatable or harmless species evolves to resemble an unpalatable or dangerous model species.
CLEP Biology Mechanisms of Natural Selection 3
Sexual selection differs from natural selection primarily because it: