The gradual change in the traits of a population over many generations is described by

• A. Variation
• B. Evolution
• C. Fossil
• D. Scientific theory

Answer: (B)

Evolution is the gradual change in the traits of a population over many generations. This happens because heritable traits affect an organism’s survival and ability to reproduce, so those traits become more or less common over time. Small genetic changes accumulate across generations, leading to noticeable shifts in a population’s characteristics. For example, if a population of beetles becomes more camouflaged to its environment, the trait that provides better camouflage becomes more common through many generations. Variation is the range of different traits already present in a population and provides the material for evolution, fossils are evidence from the past, and a scientific theory is the well-supported explanation for a broad set of observations.