The four major causes of extinction are habitat loss and fragmentation, co-extinctions, over-exploitation and invasive species.

1. Habitat loss and fragmentation: Our daily activities such as deforestation, urban development and agriculture are the causes of habitat loss and fragmentation. It reduces habitat and species richness and also causes loss of biodiversity.
2. Co-extinctions: Refers to the phenomenon where the extinction of one species directly leads to the extinction of another species with which it interacts closely. This interaction can be mutualistic, parasitic, or symbiotic. When a host species becomes extinct, its dependent species, such as parasites or mutualistic partners, may also face extinction due to the loss of their habitat or food source.
3. Over-exploitation: On a large scale, unrestricted hunting, fishing and harvesting for food, medicine and other resources leads to a rapid decline in the number of species.
4. Alien species invasion: Foreign species can easily dominate native species by competing with or becoming prey or spreading their diseases leading to ecological extinction.

Relevant Links:

• 5 Major Threats to Biodiversity
• Conservation of Forest and Wildlife
• Endemic Species – Characteristics, Types and Examples
• Endangered Species – Definition & List of Endangered Species
• How Many Species Are There On Earth And How Many In India?
• Conservation of Forest and Wildlife
• 6th Mass Extinction – Holocene Extinction
• Causes, Effects and Control of Deforestation
• Red Data Book