Question

there are four mechanisms that can cause changes in the frequencies of genes in populations: mutation, migration, genetic drift, and natural selection. all four are mechanisms of evolutionary change. compare natural selection to the other mechanisms for change. what choice best differentiates natural selection from the other mechanisms? a populations changes, from generation to generation, happen solely by chance. b individuals within a population change in a response to selective pressures in the environment. c variation within a population develops; allelic frequencies within a population change due to the influx of new genotypes. d there is variation in a population; differential reproduction occurs and over time, a more advantageous trait exists in the population.

Explanation:

Natural selection differs from other evolutionary mechanisms (mutation, migration, genetic drift) by acting on heritable variation, leading to differential reproduction of individuals with advantageous traits. Option D captures this: variation exists, differential reproduction occurs, and advantageous traits become more common over time. Option A is incorrect (natural selection is not random). Option B is wrong because individuals do not change; populations evolve. Option C describes migration/mutation, not natural selection.

Answer:

D. There is variation in a population; differential reproduction occurs and over time, a more advantageous trait exists in the population.