Question
What is a biodiversity hotspot? State the criteria for identifying a hotspot and name the four biodiversity hotspots of India.
Solution — Step by Step
A biodiversity hotspot is a biogeographic region with exceptionally high species richness, a large number of endemic species (found nowhere else), AND significant habitat loss or threat.
The term was coined by Norman Myers in 1988. Currently, there are 36 recognised hotspots worldwide, covering less than 3% of Earth’s land surface but harbouring over 50% of plant species and 42% of terrestrial vertebrates.
For a region to qualify as a biodiversity hotspot, it must meet BOTH criteria:
Criterion 1 — Richness: The region must have at least 1,500 species of vascular plants as endemics (found nowhere else on Earth).
Criterion 2 — Threat: The region must have lost at least 70% of its original habitat (i.e., retains 30% or less of its original vegetation).
Both conditions must be satisfied simultaneously. A species-rich region that faces no threat does not qualify.
India has four recognised biodiversity hotspots:
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Himalayas — includes the entire Hindu Kush-Himalayan region; rich in alpine and sub-alpine species; endemic plants like Himalayan blue poppy, snow leopard.
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Indo-Burma (also called Eastern Himalayas or Indo-Myanmar) — northeastern India (Assam, Meghalaya, Nagaland); one of the world’s richest freshwater biodiversity zones; clouded leopard, Hoolock gibbon.
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Sundaland (Western Ghats + Sri Lanka) — Western Ghats has over 5,000 plant species with ~50% endemism; lion-tailed macaque, Malabar pit viper, Nilgiri tahr.
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Western Ghats — sometimes listed separately from Sri Lanka; running along the western coast; home to nearly 77% of India’s amphibian diversity.
Note: In NCERT, these are often grouped as Western Ghats and Sri Lanka as one hotspot, and Eastern Himalayas as another. Always check your textbook edition.
India occupies only 2.4% of Earth’s land area but accounts for nearly 8% of global biodiversity — over 45,000 plant species and 90,000 animal species. The diversity stems from its varied biogeographic zones: the Himalayas act as a barrier creating distinct northern and southern climates, while the Western Ghats receive heavy monsoons creating rainforests.
Why This Works
The hotspot concept is a conservation prioritisation tool. With limited resources, we cannot protect every ecosystem equally. By identifying hotspots — regions that are both unique (high endemism) and threatened — conservationists can target their efforts where the stakes are highest.
The 1,500 endemic plant species threshold is specifically for vascular plants because they form the structural base of terrestrial ecosystems. Where plants are endemic, animals dependent on them are also often endemic.
Alternative Method — Remember with a Mnemonic
To remember the four Indian hotspots: H-I-S-W
- Himalayas
- Indo-Burma
- Sundaland
- Western Ghats
Or: “His Western India” — Himalayas, Indo-Burma, Sundaland (Western Ghats + Sri Lanka), Western Ghats.
Common Mistake
Confusing “biodiversity hotspot” with simply “a place with lots of species.” The threat criterion is equally important. Amazon rainforest has enormous diversity, but if it hasn’t lost 70% of original habitat, it doesn’t meet the full hotspot definition by Myers’ criteria. Also, many students name only 2–3 Indian hotspots — all four are needed for full marks in NEET and CBSE.