Explanation
A biodiversity hotspot is an area which has lost at least 70 per cent of its primary native vegetation
It contains at least 1,500 species of vascular plants which are endemic.
There are currently 36 recognized biodiversity hotspots.
These are Earth’s most biologically rich yet threatened terrestrial regions.
A biodiversity hotspot is a biogeographic region with a significant reservoir of biodiversity that is under threat from humans. Around the world, 25 areas qualify under definition of hotspots. These sites support nearly 60% of the world's plant, bird, mammal, reptile, and amphibian species, with a very high share of endemic species. The biodiversity hotspots hold especially high numbers of endemic species, yet their combined area of remaining habitat covers only 2.3 percent of the Earth's land surface. Each hotspot faces extreme threats and has already lost at least 70 percent of its original natural vegetation. Over 50 percent of the world’s plant species and 42 percent of all terrestrial vertebrate species are endemic to the 34 biodiversity hotspots. So, the correct answer is '2.3%'.
(i) In disruptive selection, more individuals acquire peripheral character value at both ends of the distribution curve.
(ii) Jawless fishes evolved around 320mya and seaweeds existed around 350mya.
(iii) Ichthyosaurs evolved around 200mya.
(iv) First cellular form of life evolved around 2bya.
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