Exotic species are organisms introduced by humankind to an area where they are not native (naturally found). Invasive species are organisms that can come to dominate an ecosystem to such a degree that they exclude other naturally occurring life forms. Invasive species may be exotic and are often invasive in their non-native habitat because of a lack of natural diseases and predators. Native species may also become invasive because of dramatic changes in habitat caused by human activities. Whether native or exotic, invasive species cause a general decline in ambient environmental quality by reducing the biodiversity of the impacted ecosystem.

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