Given the task definition and input, reply with output. In this task, you are given a sentence and a question, you would be asked to create the answer which is contained in the sentence provided.

Sentence: Competive exclusion princple explains why two different species cannot occupy the same niche in the same place for very long. Question: What explains why two different species cannot occupy the same niche in the same place for very long?
competive exclusion princple