What can happen if an organism's population gets too big?

If an organisms population gets too big and exceeds the carrying capacity, a lot of consequences may happen, such as fighting for food, resources, but eventually some must die off.

If the population is over the carrying capacity, resources such as land, food, or water must be limited and organisms must fight for it in order to survive. And who wins? The ones that have a favorable characteristic. They survive while others die. When the number of organisms that die exceeds the number that is born, this is the death phase in a population. Death phase is very common if the initial population gets too big.

Cartificial intelligence

That would be a working theory.