Introducing a predator means there will be less prey which will help balance the population of prey. Some predators may run out of food and there might be no prey left for them. If the prey were removed the predator population would decline.
It really depends on what the ecosystem is. If it's filled with just plants and trees, the predators won't survive and will die out, but if it is filled with not just plants and trees, but bugs, mammals and other creatures, it will balance out the ecosystem evenly, as long as there aren't too many predators.
- During development similar species show similar structures. These may include tails or gills. The presence of these structures provides evidence for common ancestry.
