Natural selection is the process by which biological evolutionary changes take place. Natural selection acts on populations and not individuals. It is based on the following concepts:
- Individuals in a population have different traits which can be inherited.
- These individuals produce more young than the environment can support.
- The individuals in a population that are best suited to their environment will leave more offspring, resulting in a change in the genetic makeup of a population.
The genetic variations that arise in a population happen by chance, but the process of natural selection does not. Natural selection is the result of the interactions between genetic variations in a population and the environment.
The environment determines which variations are more favorable. Individuals that possess traits that are better suited to their environment will survive to produce more offspring than other individuals. More favorable traits are thereby passed on to the population as a whole. Examples of genetic variation in a population include the modified leaves of carnivorous plants, cheetahs with stripes, snakes that fly, animals that play dead, and animals that resemble leaves.