Biodiversity for UPSC: Levels, Hotspots, Endemism, Loss of Species and Conservation in India
How UPSC Tests Biodiversity (the Biggest Block in the Environment Paper)
🎯 Exam priority: Tier-1, the single biggest block in the Environment paper. Over ten years of Prelims, about 42 of 180 environment questions (23 per cent) were on biodiversity, species and conservation status, and 16 of those came in the last three years. In 2024 alone there were eight species-and-organism questions. The format has changed from 'which one of these' to 'how many of the above' and statement-reasoning, so partial knowledge no longer rescues you.
Three kinds of question recur. (1) Concept and number questions from NCERT: the three levels of diversity, hotspots, endemism, the causes of extinction. (2) Species questions: where a species lives, what it eats, how it behaves; those are handled in the next four articles. (3) Policy and index questions: protected-area categories, the CBD framework, laws. This article does (1) and gives India's current numbers; species and legal status follow.
What this article gives you
The three levels of biodiversity and the numbers NCERT uses (and that UPSC copies).
Why the tropics are richer, the species-area relationship and the 'rivet popper' argument.
Hotspots and endemism, with India's four hotspots and the two tests a region must pass.
The four causes of extinction (the 'Evil Quartet') with the examples to quote.
In situ and ex situ conservation, India's current protected-area numbers from the Ministry's 2025-26 report, and the post-2022 global framework.
Levels of Biodiversity, the Species Count and India's Share
Biodiversity: three levels
The term biodiversity, popularised by the sociobiologist Edward Wilson, describes the combined diversity at all levels of biological organisation. Three levels matter:
Level | Meaning | NCERT's example |
Genetic diversity | Variation within one species across its range | The medicinal plant Rauwolfia vomitoria varies in the potency and concentration of its active chemical (reserpine) across Himalayan ranges; India has more than 50,000 genetically different strains of rice and 1,000 varieties of mango |
Species diversity | Variety of species in an area | The Western Ghats have greater amphibian species diversity than the Eastern Ghats |
Ecological (ecosystem) diversity | Variety of ecosystems | India, with deserts, rain forests, mangroves, coral reefs, wetlands, estuaries and alpine meadows, has greater ecosystem diversity than a Scandinavian country such as Norway |
How many species?
Described so far: slightly more than 1.5 million (IUCN, 2004). Robert May's conservative estimate of the global total is about 7 million (extreme guesses run to 20-50 million).
What the described species are: animals are more than 70 per cent; plants (including algae, fungi, bryophytes, gymnosperms and angiosperms) no more than 22 per cent. Among animals, insects are the most species-rich group, more than 70 per cent of animals: out of every ten animals, seven are insects. Fungal species outnumber the fishes, amphibians, reptiles and mammals put together. Prokaryotes are not counted because conventional taxonomy does not suit microbes.
India: only 2.4 per cent of the world's land area but 8.1 per cent of its species, and that is why NCERT calls it one of the mega-diverse countries (it says twelve, a reference to the early group of like-minded megadiverse countries; the commonly cited UNEP-WCMC list now has seventeen, and India is on both). Nearly 45,000 plant species and twice as many animal species have been recorded.
Patterns: Latitudinal Gradient, Species-Area Relationship and the Rivet Popper
Patterns of biodiversity
The latitudinal gradient
Species diversity generally decreases from the equator towards the poles, and the tropics (23.5° N to 23.5° S) hold more species than temperate or polar regions. NCERT's bird numbers are good exam facts: Colombia (near the equator) has nearly 1,400 bird species, New York (41° N) 105 and Greenland (71° N) only 56; India has more than 1,200. The Amazon rain forest is the most biodiverse on Earth, with more than 40,000 plant species and 1,300 bird species.
Three hypotheses explain the tropical richness, and you should be able to state all three:
Time: speciation takes time, and the tropics, unlike temperate regions hit by repeated glaciations, stayed undisturbed for millions of years.
Stability: tropical environments are less seasonal, more constant and more predictable, which favours niche specialisation.
Energy: more solar energy means higher productivity, which can support more species.
The species-area relationship
Alexander von Humboldt observed that species richness rises with the area explored, but only up to a limit; the relation is a rectangular hyperbola, and on a log scale a straight line: log S = log C + Z log A. For most groups and regions the slope Z lies between 0.1 and 0.2; across whole continents it is steeper, 0.6 to 1.2 (1.15 for fruit-eating birds and mammals in tropical forests). The practical lesson: larger habitat blocks hold more species, which is why fragmentation is so damaging.
Why diversity matters to an ecosystem
David Tilman's long-term experiments found that plots with more species showed less year-to-year variation in total biomass and higher productivity. Paul Ehrlich's rivet popper hypothesis makes the argument memorable: species are the rivets that hold an aeroplane (the ecosystem) together; removing a few may not matter, but removal continues until the plane fails, and which rivets are removed (rivets in the wings, the key species) is critical.
Hotspots and Endemism: the Two Tests and India's Four Hotspots
Hotspots and endemism
Endemism means a species is confined to one region and found nowhere else. A biodiversity hotspot is a region with very high species richness and a high degree of endemism that is also losing habitat fast. NCERT says conservationists first listed 25 hotspots, then added nine more, bringing the world total to 34. All the hotspots together cover less than 2 per cent of the Earth's land area, yet their strict protection could reduce the ongoing mass extinctions by almost 30 per cent, which is why hotspots are the main place to focus scarce conservation money.
The two tests (Conservation International)
A region qualifies as a hotspot if it (1) holds at least 1,500 species of vascular plants as endemics (about 0.5 per cent of the world's total) and (2) has lost at least 70 per cent of its original natural vegetation. (Web-verified against several sources; the older NCERT text does not give the criteria.)
India's hotspots
NCERT lists three hotspots covering India's biodiversity-rich regions: Western Ghats and Sri Lanka, Indo-Burma and the Himalaya. The standard Indian list now adds a fourth, Sundaland, represented in India by the Nicobar Islands (the Andaman Islands fall within Indo-Burma). So answer 'four' when the question says 'how many of India's...' and note that the Himalaya, Indo-Burma and Sundaland extend beyond India's borders.
Hotspot | In India | Remember |
Himalaya | The Himalayan arc, including the North-East in the east | Extends into Nepal, Bhutan and Pakistan |
Indo-Burma | North-East India (except the Brahmaputra and Barak valleys) and the Andaman Islands | Extends into Myanmar and mainland South-East Asia |
Western Ghats and Sri Lanka | The Western Ghats, run along the west coast | A UNESCO World Heritage region since 2012; amphibian-rich |
Sundaland | The Nicobar Islands | The Indian part of a larger Sunda region |
Loss of Biodiversity: the Evil Quartet and Mass Extinctions
Loss of biodiversity: the Evil Quartet
The IUCN Red List (2004) documented the extinction of 784 species (338 vertebrates, 359 invertebrates and 87 plants) in the last 500 years, among them the dodo (Mauritius), quagga (Africa), thylacine (Australia), Steller's sea cow (Russia) and three tiger subspecies (Bali, Javan and Caspian). More than 15,500 species worldwide face extinction. NCERT gives the threatened shares as: 12 per cent of birds, 23 per cent of mammals, 32 per cent of amphibians and 31 per cent of gymnosperms. Amphibians are the most vulnerable group.
Life has seen five mass extinctions; the current 'sixth extinction' differs in its rate: 100 to 1,000 times faster than before humans, and caused by human activity. If trends continue, nearly half of all species could be wiped out within about 100 years. NCERT lists four causes, the 'Evil Quartet':
Cause | What it means | Example to quote |
1. Habitat loss and fragmentation (the most important) | Total loss, degradation by pollution, and break-up into fragments that hurt wide-ranging and migratory animals | Tropical rain forests once covered more than 14 per cent of the land and now cover no more than 6 per cent; the Amazon is cleared for soya and cattle pasture |
2. Over-exploitation | Taking more than nature can replace | Steller's sea cow and the passenger pigeon; over-harvested marine fish |
3. Alien species invasions | Introduced species turn invasive and displace natives | The Nile perch in Lake Victoria wiped out more than 200 cichlid fish species; Parthenium, Lantana and water hyacinth in India; the African catfish Clarias gariepinus threatening native catfishes |
4. Co-extinctions | A species dies and species tied to it die too | A host fish and its parasites; a plant and its obligate pollinator |
Loss of biodiversity in a region lowers plant production, weakens resistance to droughts and increases variability in processes such as water use and pest and disease cycles.
Conservation: In Situ, Ex Situ, India's Network and the Global Framework
Why conserve, and how
NCERT groups the reasons into three: narrowly utilitarian (food, fibre, firewood, medicines: more than 25 per cent of the drugs sold worldwide come from plants and 25,000 plant species feed traditional medicine), broadly utilitarian (ecosystem services such as pollination, flood control and oxygen; NCERT credits the Amazon with about 20 per cent of the atmosphere's oxygen) and ethical (every species has intrinsic value).
In situ and ex situ
In situ (on site) | Ex situ (off site) | |
Idea | Protect the whole ecosystem: 'save the forest to save the tiger' | Take threatened species out of the wild for special care |
When | The general approach | When a species faces a very high risk of extinction and needs urgent measures |
Tools | Biosphere reserves, national parks, sanctuaries, sacred groves, hotspots | Zoos, botanical gardens, safari parks, cryopreserved gametes, in vitro fertilisation, tissue culture, seed banks |
Sacred groves (Khasi and Jaintia Hills in Meghalaya, the Aravallis in Rajasthan, the Western Ghats of Karnataka and Maharashtra, and parts of Madhya Pradesh) are community-protected forest tracts that serve as the last refuges of rare plants.
India's network today (use these, not the old textbook counts)
NCERT quotes 14 biosphere reserves, 90 national parks and 448 sanctuaries; the Ministry's 2025-26 Annual Report gives the current position:
688 national parks and wildlife sanctuaries; the total number of Protected Areas has risen to 1,134 (the larger figure includes the community and conservation reserves).
58 tiger reserves in 18 range States under Project Tiger.
13 biosphere reserves in UNESCO's World Network, the highest in South Asia; the Cold Desert Biosphere Reserve was the new addition.
International framework
The Convention on Biological Diversity, one of the agreements of the 1992 Rio Earth Summit, has three objectives: conservation, sustainable use, and fair and equitable sharing of benefits from genetic resources. India enacted the Biological Diversity Act in 2002 to give effect to it. In 2002 the Johannesburg summit pledged to cut the rate of biodiversity loss by 2010. The current framework is the Kunming-Montreal Global Biodiversity Framework: India submitted 23 national targets in line with it on 10 September 2024 and an updated National Biodiversity Strategy and Action Plan (NBSAP 2024-2030) on 31 October 2024. (The laws and the Red List are in the conservation-status article; the protected-area categories in the protected-areas article.)
India's Biogeographic Zones and How UPSC Could Ask This Next
India's biogeographic zones (standard reference)
India is divided into ten biogeographic zones, which the Wildlife Institute of India subdivides into 25 biotic provinces: the Trans-Himalaya, Himalaya, Desert, Semi-Arid, Western Ghats, Deccan Peninsula, Gangetic Plain, Coasts, North-East and Islands. A question may ask which zone holds a given species or protected area, so attach each large protected area to its zone as you read the species articles. (Standard classification; confirm the provincial numbering from the Wildlife Institute of India if you need it.)
How UPSC Could Ask This Next
Numbers: India's share of global area and species, the number of hotspots in India and in the world, the share of land the hotspots cover.
Statement-reasoning: 'Tropical regions have higher species richness because they receive more solar energy' with the reasoning to evaluate.
Species-and-place pairs: which animal is naturally found in which country (2019 and 2024 asked this), and which species is endemic to India.
Causes and examples: match an invasive species or an extinct animal to the cause (the Nile perch, Parthenium, Steller's sea cow).
Current framework: KMGBF targets and the NBSAP, protected-area totals (the new Annual Report figures).
Further Reading
NCERT Biology (Class 12) and Geography textbooks, the India State of Forest Report, the MoEFCC Annual Report, the Economic Survey and the official lists cited in this note — the primary sources behind every figure above.
Test Yourself: Practice Questions and PYQs
Fourteen practice questions on biodiversity levels, patterns, hotspots, causes of loss and conservation, followed by the real UPSC Prelims questions on the topic and the exact Mains questions.
Practice Questions
Q1. Consider the following statements about biodiversity levels:
1. Variation in the potency of reserpine in Rauwolfia growing in different Himalayan ranges is an example of genetic diversity.
2. The greater amphibian diversity of the Western Ghats than of the Eastern Ghats is an example of species diversity.
3. India's deserts, mangroves, coral reefs and alpine meadows are an example of ecological diversity.
Which of the statements given above are correct?
(a) 2 and 3 only
(b) 1, 2 and 3
(c) 1 and 2 only
(d) 1 and 3 only
Show answer
Answer: (b) — All three match NCERT's examples of genetic, species and ecosystem diversity.
Q2. India has about 2.4 per cent of the world's land area. According to NCERT, its share of global species diversity is about
(a) 2.4 per cent
(b) 17 per cent
(c) 8.1 per cent
(d) 25 per cent
Show answer
Answer: (c) — India holds about 8.1 per cent of the world's species despite 2.4 per cent of the land, which is why it is a megadiverse country.
Q3. Among the animals described so far, which is the most species-rich taxonomic group?
(a) Mammals
(b) Birds
(c) Insects
(d) Fishes
Show answer
Answer: (c) — Insects are more than 70 per cent of all animal species: of every ten animals, seven are insects.
Q4. Statement-I: Species diversity generally decreases from the equator towards the poles.
Statement-II: The tropics receive more solar energy, which contributes to higher productivity and, indirectly, to greater species diversity.
Which one of the following is correct in respect of the above statements?
(a) Statement-I is incorrect but Statement-II is correct
(b) Both statements are correct and Statement-II is a correct reason for Statement-I
(c) Both statements are correct but Statement-II is not a correct reason for Statement-I
(d) Statement-I is correct but Statement-II is incorrect
Show answer
Answer: (b) — The latitudinal gradient is explained by time, stability and energy; more solar energy is one of the three hypotheses.
Q5. The relationship between species richness (S) and area (A) is described by log S = log C + Z log A. Which statement about Z is correct?
(a) It is always exactly 1
(b) It has no relation to the area
(c) It is usually 0.1 to 0.2 for areas within a region, and steeper (0.6 to 1.2) across entire continents
(d) It is larger for small areas than for continents
Show answer
Answer: (c) — For most taxa in ordinary regions Z is 0.1-0.2; analysing whole continents gives much steeper slopes.
Q6. Consider the following statements about biodiversity hotspots:
1. They are regions with high species richness and high endemism that are also losing habitat rapidly.
2. The world has 34 biodiversity hotspots according to NCERT.
3. All the hotspots together cover more than 20 per cent of the Earth's land area.
Which of the statements given above are correct?
(a) 2 and 3 only
(b) 1, 2 and 3
(c) 1 and 2 only
(d) 1 and 3 only
Show answer
Answer: (c) — Hotspots together cover less than 2 per cent of the land, so 3 is wrong.
Q7. How many of the following are biodiversity hotspots that include parts of India?
1. Himalaya
2. Indo-Burma
3. Western Ghats and Sri Lanka
4. Sundaland
(a) All four
(b) Only three
(c) Only two
(d) None
Show answer
Answer: (a) — India's four hotspots: Himalaya, Indo-Burma, Western Ghats and Sri Lanka, and Sundaland (the Nicobar Islands). NCERT lists only the first three.
Q8. Which one of the following is NOT one of the four major causes of biodiversity loss described as the 'Evil Quartet'?
(a) Over-exploitation
(b) Climate-driven shifts in monsoon timing
(c) Alien species invasions
(d) Habitat loss and fragmentation
Show answer
Answer: (b) — The Evil Quartet is habitat loss and fragmentation, over-exploitation, alien species invasions and co-extinctions.
Q9. The introduction of the Nile perch into Lake Victoria is an example of which cause of species loss?
(a) Alien species invasion
(b) Co-extinction
(c) Habitat fragmentation
(d) Over-harvesting of the perch itself
Show answer
Answer: (a) — The Nile perch led to the extinction of more than 200 species of cichlid fish in the lake, a classic invasive-species case.
Q10. Consider the following invasive plants that threaten India's native species:
1. Parthenium (carrot grass)
2. Lantana
3. Water hyacinth
How many of the above are named by NCERT as invasive weeds in India?
(a) Only one
(b) None
(c) Only two
(d) All three
Show answer
Answer: (d) — NCERT names Parthenium, Lantana and water hyacinth (Eichhornia) as invasive weed species.
Q11. Which one of the following is an ex situ conservation method?
(a) A biosphere reserve
(b) Cryopreservation of gametes of threatened species
(c) A sacred grove
(d) A national park
Show answer
Answer: (b) — Ex situ methods take species out of their natural habitat: zoos, botanical gardens, cryopreservation, tissue culture and seed banks. The others protect species in situ.
Q12. Which of the following is/are correct about the Convention on Biological Diversity?
1. It was among the agreements adopted at the 1992 Earth Summit in Rio de Janeiro.
2. One of its objectives is the fair and equitable sharing of benefits from the use of genetic resources.
3. India gave effect to it through the Biological Diversity Act, 2002.
(a) 2 and 3 only
(b) 1, 2 and 3
(c) 1 and 2 only
(d) 1 and 3 only
Show answer
Answer: (b) — All three are correct: the CBD's objectives are conservation, sustainable use and fair and equitable sharing, and India enacted its Act in 2002.
Q13. According to the Ministry of Environment, Forest and Climate Change's Annual Report 2025-26, India has how many biosphere reserves in UNESCO's World Network of Biosphere Reserves?
(a) 18
(b) 13
(c) 10
(d) 22
Show answer
Answer: (b) — The report says India has 13 in the UNESCO network, the highest in South Asia, after the Cold Desert Biosphere Reserve was added.
Q14. In the context of the Kunming-Montreal Global Biodiversity Framework, India submitted its national targets and an updated National Biodiversity Strategy and Action Plan to the CBD in 2024. The number of national targets India submitted was
(a) 12
(b) 17
(c) 30
(d) 23
Show answer
Answer: (d) — India submitted 23 national targets on 10 September 2024 and its updated NBSAP (2024-2030) on 31 October 2024.
UPSC Previous Year Questions (PYQs)
Real UPSC Prelims questions, checked against the official paper and answer key.
Q1. (2019) Consider the following statements:
1. Asiatic lion is naturally found in India only.
2. Double-humped camel is naturally found in India only.
3. One-horned rhinoceros is naturally found in India only.
Which of the statements given above is/are correct?
(a) 2 only
(b) 1, 2 and 3
(c) 1 and 3 only
(d) 1 only
Show answer
Answer: (d) — Only the Asiatic lion (Gir, Gujarat) is naturally restricted to India. The double-humped (Bactrian) camel is native to Central Asia, and the one-horned rhinoceros also lives in Nepal.
Q2. (2024) Consider the following pairs : Country Animal found in its natural habitat
1. Brazil Indri
2. Indonesia Elk
3. Madagascar Bonobo
How many of the pairs given above are correctly matched ?
(a) All three
(b) Only two
(c) Only one
(d) None
Show answer
Answer: (d) — The indri is endemic to Madagascar (not Brazil), elk are northern-hemisphere deer (Indonesia has none), and bonobos live only in the Democratic Republic of the Congo (not Madagascar). None of the pairs is correct.
Q3. (2023) Consider the following statements: Statement-I: Marsupials are not naturally found in India. Statement-II: Marsupials can thrive only in montane grasslands with no predators. Which one of the following is correct in respect of the above statements?
(a) Statement-I is incorrect but Statement-II is correct
(b) Both Statement-I and Statement-II are correct and Statement-II is not the correct explanation for Statement-I
(c) Both Statement-I and Statement-II are correct and Statement-II is the correct explanation for Statement-I
(d) Statement-I is correct but Statement-II is incorrect
Show answer
Answer: (d) — Marsupials are native to Australasia and the Americas, not India, so Statement-I is right. They live in forests, scrub and grasslands, not only montane grasslands without predators, so Statement-II is wrong.
Q4. (2019) Consider the following pairs: Wildlife Naturally found in
1. Blue-finned Mahseer : Cauvery River
2. Irrawaddy Dolphin : Chambal River
3. Rusty-spotted Cat : Eastern Ghats
Which of the pairs given above are correctly matched?
(a) 2 and 3 only
(b) 1, 2 and 3
(c) 1 and 3 only
(d) 1 and 2 only
Show answer
Answer: (c) — Blue-finned mahseer is a Cauvery fish and the rusty-spotted cat is found in the Eastern Ghats (as well as the Western Ghats and Sri Lanka). The Irrawaddy dolphin lives in the Irrawaddy, the Mekong and Chilika Lake, not the Chambal, so only 1 and 3 are right.
Mains Practice Questions
Use these to frame full-length answers. You don't have to answer one exactly — they show the angles UPSC tests, so let them guide which points you cover.
Why is India considered a megadiverse country? Examine the threats to its biodiversity and the role of the hotspots in conservation planning.
Explain the latitudinal gradient in species diversity and the hypotheses that account for it. How does the species-area relationship help conservation planning?
What are the four major causes of biodiversity loss? Illustrate each with Indian examples.
Distinguish between in situ and ex situ conservation. Evaluate the relative merits of each for India's endangered species.
Discuss the aim and goals of the Kunming-Montreal Global Biodiversity Framework. Mention India's commitments and initiatives to achieve the targets.
UPSC Mains — Previous Years’ Questions on this topic (last 10 years)
These are the actual GS Mains questions UPSC has asked on this theme — real proof of how, and when, it is tested. Try to write a full answer to each.
2026 (GS-III): Discuss the aim and goals of Kunming-Montreal global biodiversity framework. Mention India's commitments and initiatives to achieve the goals and targets of this framework giving suitable examples. (Answer in 150 words)
2018 (GS-III): How does biodiversity vary in India? How is the Biological Diversity Act, 2002 helpful in conservation of flora and fauna?