It is a species introduced by humans – either intentionally or accidentally – outside its natural past or present distribution It is these species that are termed ‘Invasive alien species’ (IAS). However, not all alien species have negative impacts.
Impact
- Driver of biodiversity loss
- Leads to changes in structure & composition of ecosystems leading to detrimental impact on ecosystem services and humans.
Common Invasive Species of India
| Flagship species | Indicator species | Keystone species |
| Species chosen to represent an environmental cause, such as an ecosystem in need of conservation. | Species whose presence indicates, presence of a set of other species and health of ecosystem. | It is a species whose addition or loss to an ecosystem will lead to major changes in the ecosystem. |
| Chosen species could be either vulnerable/ attractive/ distinct. | Ex. A species might indicate presence of environmental pollution or arrival of monsoon etc. | As certain species are considered more important in determining the presence of other species. |
| Ex.: Indian Tiger, African Elephant, Giant Panda of China, etc. | Ex.: Lichens (air quality), most amphibians, fishes, etc. | Ex.: Top predator tiger, lion, crocodile etc. Their removal will distort existing food chains. |
