Question
What is a biodiversity hotspot? What criteria define a hotspot? Explain why the Western Ghats is recognised as a biodiversity hotspot.
(NCERT Class 12, commonly asked in NEET)
Solution — Step by Step
A biodiversity hotspot is a biogeographic region that has exceptionally high species richness (especially endemic species) and is experiencing significant habitat loss. The concept was introduced by Norman Myers (1988) and later refined by Conservation International.
Currently, 36 biodiversity hotspots have been identified worldwide, covering just 2.5% of Earth’s land surface but harbouring over 50% of the world’s plant species and 42% of terrestrial vertebrate species as endemics.
A region must meet BOTH criteria to qualify as a hotspot:
- High endemism: Must contain at least 1,500 species of vascular plants (more than 0.5% of the world total) as endemics (found nowhere else).
- High threat: Must have lost at least 70% of its original habitat (primary vegetation).
Both conditions are essential — a species-rich area that is not threatened, or a threatened area with low endemism, does not qualify.
The Western Ghats mountain range runs ~1,600 km along India’s western coast (from Gujarat to Tamil Nadu). It qualifies as a hotspot because:
High endemism:
- Over 5,000 flowering plant species, of which ~1,700 are endemic
- ~325 globally threatened species (IUCN Red List)
- High endemism in amphibians (~80% of peninsular amphibians are endemic), reptiles, and freshwater fish
- Unique species: Lion-tailed macaque, Nilgiri tahr, Malabar civet, and hundreds of endemic orchids and medicinal plants
Severe habitat loss:
- Only about 6-7% of the original primary vegetation remains intact
- Threats include deforestation for tea/coffee/rubber plantations, urbanisation, mining, and dam construction
- Fragmentation has isolated populations, reducing genetic diversity
The Western Ghats was declared a UNESCO World Heritage Site in 2012.
Why This Works
Hotspot designation is a conservation prioritisation strategy. Since resources for conservation are limited, focusing on hotspots — regions where many unique species face imminent extinction — delivers the maximum conservation benefit per rupee spent. Protecting 36 hotspots could conserve over half the world’s endemic species.
India has 4 biodiversity hotspots: Western Ghats, Eastern Himalayas, Indo-Burma region, and Sundaland (includes Nicobar Islands).
NEET commonly tests the two criteria (1,500 endemic plant species + 70% habitat loss). Also frequently asked: “How many hotspots are in India?” Answer: 4. Know at least two specific examples of endemic species from the Western Ghats for descriptive questions.
Common Mistake
Students often write that a hotspot is any area with “high biodiversity.” High biodiversity alone is not enough — the region must also show high endemism (not just species richness) AND significant habitat loss. The Amazon rainforest has enormous biodiversity but is not classified as a single hotspot because its original habitat was relatively intact when the concept was defined (though parts now face severe deforestation).
Another error: confusing endemic with endangered. Endemic species are found only in a particular region — they may or may not be endangered. However, endemic species in hotspots are at high risk because their small range + habitat loss = vulnerability to extinction.