Class 12th Biology 2017 Set1 Delhi Board Paper Solution
Name and describe any three causes of biodiversity losses.
Causes of biodiversity losses:
1. Habitat Loss and Fragmentation:
This is the most important cause driving animals and plants to extinction. The most dramatic example of habitat loss come from tropical rain forests.The Amazon rain forest harbouring probably millions of species is being cut and cleared. When large habitats are broken up into small fragments due to various human activities, mammals and birds requiring large territories and certian animals with migratory habitats are badly affected, leading to population declines.
2. Over exploitation:
Humans are always depens on nature for food and shelter, but when need turns to greed, it leads to over exploitation of natural resources.
For example, Steller’s sea cow, passenger pigeon and many marine fishes have extincted in last 500 years.
3. Co-extinction:
When a species become extinct, the plant and animal species associated with it an obligatory way also become extint.
For example: Nile perch a large predator fish when introduced in Lake Victoria (East Africa) caused by extinction of an ecologically unique species of cichlid fish in the lake
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