Question

a) What is endemism?
                   b) Mention ‘The Evil Quartet’ of biodiversity loss.

Answer 1

Hint: a) Endemism is that state where the specific species are found in some specific region only. For example: Kangaroos were originally endemic to the country Australia means they are found in that specific country only and are not found anywhere else.
b) ‘The Evil Quartet’ is a sobriquet (nickname) that describes the four major causes which are responsible for extinction of species at an accelerated rate. There is a loss of biodiversity because of 4 main reasons that were known as the four horsemen.

Complete answer:
a)Endemism is that ecological state where a specific species is native to a specific area or some defined geographic location like any island, any country, or some specific type of habitat. This occurs when some plant or animal species grow in some particular place and adapt to the environmental conditions of that specific region.

b) ‘The Evil Quartet’ of biodiversity loss is a concept that describes the reason that causes extinction of species. These main four reasons are overexploitation, loss of habitat, extinction of species continuously and introduction of the exotic species.

i) Overexploitation- Overexploitation means harvesting species at a faster rate that any natural population cannot recover at this accelerated rate. Overhunting and overfishing are both types of overexploitation.

ii) Loss of habitat- When a natural habitat is not capable of supporting species that are native to it is called loss of habitat or habitat destruction.

iii) Extinction of species- Extinction of any species occur when species are decreased because of environmental forces and sometimes also because of evolutionary changes in their members.

iv) Introduction of exotic species- When foreign species or a species living in some other habitat move to the habitat of other species due to human disturbances or accidentally it is called introduction of exotic species.

Note: These four main reasons are main reasons for the loss of biodiversity, because of this the naturally existing species or native species of that specific geographical region get disturbed and start reducing in number and hence make the species endangered and finally extinct.