Here's why:

* Favorable Variation: Organisms with traits that give them an advantage in their environment (like better camouflage, stronger immunity, or more efficient food gathering) are said to have favorable variations.

* Reproductive Success: These favorable variations allow the organisms to survive longer, reproduce more, and pass those beneficial traits onto their offspring.

* Less Variations: Organisms with less favorable variations might not survive as long or reproduce as often, leading to a decrease in their representation in the population over time.

In essence, natural selection is the process by which organisms with traits better suited to their environment survive and reproduce more successfully, passing those advantageous traits on to future generations.