(a). Habitat loss and fragmentation

• It is the primary cause for extinction.
• The tropical rain forests initially covered 14% of the land surface of the earth, but now they cover only 6% of land area.
• Total loss of a habitat deprives many animals and plants of their homes and they face extinction.
• When a large habitat becomes fragmented, animals requiring large territories and those with certain migratory habits start decreasing. 

(b). Ex- situ and In-situ are two different ways of biodiversity conservation: 

1. Ex- situ conservation:- When there are situations where an animal or plant is endangered or threatened and needs urgent measures to save it from extinction, ex-situ (off-site) conservation is the desirable approach. Example - zoological parks, botanical garden and wildlife safaris. 

2. In-situ conservation:- When we conserve and protect the whole ecosystem, its biodiversity at all levels is protected. We save the entire forest to save the tiger. This approach is called in-situ (on-site) conservation. Example -biosphere reserves, national parks, and biodiversity hotspots