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Multiple Choice
Which of the following statements best describes frequency-dependent selection?
A
Individuals with intermediate traits have higher fitness than those with extreme traits.
B
The fitness of a phenotype depends on how common or rare it is in the population.
C
Natural disasters randomly reduce population size, altering allele frequencies.
D
A single allele provides a consistent advantage regardless of its frequency.
Verified step by step guidance
1
Understand the concept of frequency-dependent selection: It refers to a situation where the fitness of a phenotype depends on its frequency in the population. This means that the advantage or disadvantage of a trait changes based on how common or rare it is.
Eliminate incorrect options by analyzing their definitions: For example, the statement 'Individuals with intermediate traits have higher fitness than those with extreme traits' describes stabilizing selection, not frequency-dependent selection.
Evaluate the statement 'Natural disasters randomly reduce population size, altering allele frequencies': This describes genetic drift, specifically a bottleneck effect, and is unrelated to frequency-dependent selection.
Analyze the statement 'A single allele provides a consistent advantage regardless of its frequency': This describes directional selection, where one allele is consistently favored, and does not depend on its frequency.
Conclude that the correct statement is 'The fitness of a phenotype depends on how common or rare it is in the population,' as this directly aligns with the definition of frequency-dependent selection.