Question

what do you mean by biological hotspot ?

Answer 1

some biological areas which have almost lost their original habitat...

Answer 2

qualify as a biodiversity hotspot on Myers 2000 edition of the hotspot-map, a region must meet two strict criteria: it must contain at least 0.5% or 1,500 species of vascular plants as endemics, and it has to have lost at least 70% of its primary vegetation.[6] Around the world, 36 areas qualify under this definition.[7] These sites support nearly 60% of the world's plant, bird, mammal, reptile, and amphibian species, with a very high share of those species as endemics. Some of these hotspots support up to 15,000 endemic plant species and some have lost up to 95% of their natural habitat.[7]

Biodiversity hotspots host their diverse ecosystems on just 2.3% of the planet's surface,[8] however, the area defined as hotspots covers a much larger proportion of the land. The original 25 hotspots covered 11.8% of the land surface area of the Earth.[9] Overall, the current hotspots cover more than 15.7% of the land surface area, but have lost around 85% of their habitat.[10] This loss of habitat explains why approximately 60% of the world's terrestrial life lives on only 2.3% of the land surface area.