Final answer:
Natural selection is the process by which better-adapted organisms survive and reproduce more offspring. Its effects can be seen in Darwin's finches, where the beak size changes based on seed availability.
Step-by-step explanation:
The process where organisms that are better adapted to a particular environment survive and produce more offspring is known as natural selection. It is a force of evolution in which some living things produce more offspring than others, leading to a change in the characteristics of organisms over time. For example, Darwin's finches have different beak sizes that change depending on the availability of different-sized seeds. This is an adaptation that allows the finches to better survive and reproduce in their specific environment.