How does natural selection affect animal behavior and how behaviors can affect the survival of an animal species?

Well, technically what happens in natural selection is that the organisms with favorable traits that help them survive live long enough to pass their traits down through offspring. All the good traits passed down to the next generation help them. It would bring certain behaviors that are crucial for survival. The traits, if passed down for long enough, can affect the whole species, and eventually, the whole species can have that trait (ex. speed, agility, etc.)

Very hard to understand

He used pea plants to study the patterns of heredity.