Natural Selection

1. Identify the variation in the population. 2. Check which variation helps survival. 3. Note that better-suited organisms survive and reproduce more. 4. Track the trait over generations. 5. State that the useful trait becomes more common.

A before-and-after population sketch or a simple survival chart helps show how one trait becomes common over generations.

A common wrong answer is to say all organisms in a population change together at once. Natural selection works through differential survival and reproduction over generations.

Natural selection is the process in which organisms with useful variations survive and reproduce more successfully in a particular environment.

Natural selection is the process in which organisms with useful variations survive and reproduce more successfully in a particular environment. Natural selection favours variations that improve survival and reproduction in a given environment. If darker insects are better hidden from birds on dark tree bark, they survive more often and produce more young with the same feature. This is natural selection.

Natural selection acts on variation. In any population, some organisms have features that help them survive better in a given environment. These organisms are more likely to live long enough to reproduce and pass the helpful traits to the next generation. Over many generations, the useful trait becomes more common in the population. Natural selection favours variations that improve survival and reproduction in a given environment. In a habitat with dark tree bark, darker insects are less easily seen by birds. More dark insects survive, more of them reproduce, and their trait becomes common in later generations. Explain why a particular trait increases in a population, or describe the role of survival and reproduction in evolution. A common wrong answer is to say all organisms in a population change together at once. Natural selection works through differential survival and reproduction over generations.