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

The process of natural selection is a part of the evolution process. Let's take a herd of animals that live together so as to defend themselves and survive. If animals from the herd don't live by herd rules or similar, they will get eaten by predators or die. In time, the rebellious animals will die out leaving only those that live as a herd, and this trait will be transferred to their off-springs who will in turn behave as the herd too.

Natural selection is the gradual process by which biological traits become either more or less common in a population as a function of the effect of inherited traits on the differential reproductive success of organisms interacting with their environment. It is a key mechanism of evolution. The term "natural selection" was popularized by Charles Darwin who intended it to be compared with artificial selection, which is now called selective breeding.