Hello!

A biodiversity hotspot is a biogeographic region that is :

• a significant reservoir of biodiversity
• is threatened with destruction.

The term biodiversity hotspot specifically refers to 25 biologically rich areas around the world that have lost at least 70 % of their original habitat.

The remaining natural habitat in these biodiversity hotspots amounts to just 1 .4 % of the land surface of the planet, yet supports nearly 60 % of the world's plant, bird, mammal, reptile, and amphibian species.

Mega diversity nations are characterised by high species richness and more number of endemic species. Simply put, India  is a mega diversity country because though it consists of only 2.4% of the land area of the world, yet it accounts for 7.8% of the recorded species of the world.

Hope this helps!