Question

It is necessary to have limitations in an environment because if not:

Traits from species would get crossed.
Water and shelter would be automatically created by extra species that are new.
The populations of the world would soon crowd one another out and make conditions unlivable.
The world would balance itself out without problems.
animals.
Plants would take over the space of animals

Answer 1

Best guess is "The populations of the world would soon crowd one another out and make conditions unlivable."