Natural selection is a key process in evolution. It helps explain how certain traits become more common in a group of living things over time. The idea is often summed up as "survival of the fittest." This just means that the environment can affect which individuals survive and reproduce.

Key Components:

1. Variation: In any group of living things, you can see differences in traits. For example, some animals might be lighter in color while others are darker or different sizes.

2. Differential Survival: Some traits help individuals survive better than others. This gives them a better chance to reproduce. A good example is the peppered moth. In polluted areas, almost all dark moths survived, while fewer than 5% of light moths made it.

3. Reproduction: Those who have traits that help them survive are more likely to reproduce. This means their traits will be passed down to their offspring.

Statistics:

• In nature, about 90% of species don’t survive for more than 1 million years.
• Research shows that natural selection can increase the frequency of certain traits by 20% in each generation if the pressures are strong.

In summary, natural selection helps shape the variety of traits in living things. It allows groups to adapt to changes in their environment.