Elaborate how invasion by an alien species reduces diversity of an area.

Explanation

(i) The vigorously growing alien species competas with less vigorously local species and cause them to eliminate.
(ii) The natural pests and predators of the alien species may not be present in the introduced area, resulting proliferation of alien species.
(iii) Alien species may harm the local species by the secretion of chemicals (Amensalism).