How does natural selection affect allele frequencies in a population?

• A. It causes allele frequencies to remain constant
• B. It favors individuals with advantageous traits, increasing their allele frequencies
• C. It decreases the genetic diversity of the population
• D. It randomly affects allele frequencies

Answer: (B)

Natural selection is a key mechanism of evolution that influences allele frequencies within a population. It operates by favoring individuals that possess advantageous traits, which enhances their chances of survival and reproduction in a specific environment. As these individuals reproduce, the alleles corresponding to beneficial traits become more common over generations, leading to an increase in their frequencies within the population.

This process can result in certain favorable alleles spreading through the population while others may diminish or disappear, depending on their impact on the organism's fitness. The result is a population that may exhibit adaptations suited to its environment, demonstrating how natural selection shapes the genetic landscape over time.

In contrast to this positive selection scenario, the other options do not accurately describe the dynamics induced by natural selection. The idea that allele frequencies remain constant fails to recognize that natural selection actively changes them based on the advantages conferred by specific traits. Furthermore, while natural selection can influence genetic diversity, it does not inherently decrease it; rather, it can sometimes preserve or enhance diversity by maintaining a variety of advantageous traits in a population. Lastly, stating that natural selection randomly affects allele frequencies misrepresents its systematic nature, as natural selection acts based on the non-random survival of those with favorable traits.