What effect does natural selection have on the allele frequency of a population?

• A. It decreases genetic variation by eliminating all recessive alleles.
• B. It increases the frequency of alleles that confer a selective advantage.
• C. It randomly changes allele frequencies without regard to fitness.
• D. It causes all allele frequencies to remain constant over time.

Answer: (B)

Verified step by step guidance

1. Understand the concept of natural selection: Natural selection is a process where individuals with traits that confer a selective advantage are more likely to survive and reproduce, passing those advantageous traits (and their associated alleles) to the next generation.
2. Analyze the effect of natural selection on allele frequency: Natural selection increases the frequency of alleles that provide a selective advantage because individuals with these alleles are more likely to reproduce successfully.
3. Clarify why genetic variation is not eliminated: Natural selection does not eliminate all recessive alleles. Recessive alleles can persist in a population, especially if they are carried by heterozygous individuals who do not express the recessive trait.
4. Explain why allele frequencies do not remain constant: Natural selection causes allele frequencies to change over time, favoring alleles that improve fitness and reducing the frequency of alleles that are disadvantageous.
5. Address the randomness misconception: Natural selection is not random. It is a non-random process driven by differential survival and reproduction based on fitness, unlike genetic drift, which is random.