1. More organisms are produced than can survive. In any given environment, resources are limited. This means that not all organisms that are born will be able to survive.

2. There is variation among individuals. No two organisms are exactly the same. This means that some organisms are better adapted to their environment than others.

3. Better-adapted organisms are more likely to survive and reproduce. Organisms that are better adapted to their environment are more likely to survive and reproduce. This is because they are able to compete more successfully for resources.

4. Over time, this process of natural selection leads to the evolution of new species. As better-adapted organisms survive and reproduce, their traits become more common in the population. Over time, this can lead to the evolution of new species.