Which statement about natural selection is true?

Which statement about natural selection is true?

• A. It acts on the entire species as a single unit.
• B. It requires conscious effort by organisms to adapt.
• C. It results in perfect adaptation.
• D. It describes differential survival and reproduction due to heritable variation

Answer: (D)

Natural selection is the process by which individuals with heritable traits that help them survive or reproduce leave more offspring. This creates differential survival and reproduction, and over generations the traits that improve fitness in a given environment become more common in the population. The key idea is heritable variation—only traits that can be passed down can accumulate through generations, so changes persist. It isn’t something the whole species does as one unit; rather, variation among individuals leads to some reproducing more than others, and those differences spread through the population over time. It doesn’t require conscious effort from organisms, and it doesn’t produce perfect adaptation—environments change and there are trade-offs, so even well-suited traits aren’t perfect in every situation. Examples like the peppered moth or the spread of antibiotic resistance illustrate how differential survival and reproduction based on heritable traits shifts trait frequencies across generations.

Natural selection is the process by which individuals with heritable traits that help them survive or reproduce leave more offspring. This creates differential survival and reproduction, and over generations the traits that improve fitness in a given environment become more common in the population. The key idea is heritable variation—only traits that can be passed down can accumulate through generations, so changes persist. It isn’t something the whole species does as one unit; rather, variation among individuals leads to some reproducing more than others, and those differences spread through the population over time. It doesn’t require conscious effort from organisms, and it doesn’t produce perfect adaptation—environments change and there are trade-offs, so even well-suited traits aren’t perfect in every situation. Examples like the peppered moth or the spread of antibiotic resistance illustrate how differential survival and reproduction based on heritable traits shifts trait frequencies across generations.