sometimes alien species affect the indigenous organisms leading to their extinction. substabtiate this statement with the help of any two examples.
Indigenous species refers to the species which has been existed and adapted to a particular kind of region since long time while an alien species refers to the new kind of species invading that particular kind of area interfering and disturbing the existence of the indigenous species and its biodiversity. If a new species inhabits the same area as that of the existing one, it disturbs the activities, food and ecology of that area. Those two species then compete for food and other resources present in that area. Sometime the alien species become more adaptive to that area as compared to the indigenous species leading to the extinction of the latter.
For example, purple loosestrife is and ornamental plant, which when released into waterways over grow quickly resulting in the choking of the native plants and also interfere with the flow of lakes, streams, rivers etc.
Also, alien species like cane toad are intentionally introduced in some areas to reduce the number of native species of that area.