Could have a negative effect on everything in the environment. Each thing usually effects another. Another type of animal or a plant now may be effected, be uncontrolled, or die out with the loss of an animal that helps with control or pollination or effects in any way which effects something else, and something else and so on and so on. If they are gone the effects of their mere existence and the role they play in essentially life itself would be gone too and may be a very bad thing for other animals and the environment itself. The loss of one species can effect the rest of the ecosystem and to disastrous results in tons of ways.
