competitive exclusion principle

[kəm-pĕtĭ-tĭv]
  1. The principle that when two species compete for the same critical resources within an environment, one of them will eventually outcompete and displace the other. The displaced species may become locally extinct, by either migration or death, or it may adapt to a sufficiently distinct niche within the environment so that it continues to coexist noncompetitively with the displacing species. Also called Gause's law
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