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Quick recap: Biodiversity on one page

Biodiversity · Quick recap · Fact-checked on · how we check

Written with AI from the sources listed at the bottom of this page, then fact-checked by a separate AI.

Both parts of Biodiversity condensed for quick revision: levels and measures, India's megadiversity, hotspots and zones; values, threats, extinctions, the IUCN Red List and conservation; a one-table overview and eight mixed questions.

biodiversity is the variety of life at three nested levels: genes within a species, species in a place, and ecosystems across a landscape. The Convention on Biological Diversity (1992) uses exactly these three in its Article 2. Ecologists measure it by richness and evenness, and by Whittaker's alpha (within a habitat), beta (between habitats) and gamma (a whole region) diversity. Species numbers peak near the equator and thin out with rising latitude, and a bigger area holds more species, though the count grows more slowly than the area.

With roughly 2.4 per cent of the Earth's land, India carries some 7 to 8 per cent of all recorded species and is counted among the 17 megadiverse countries. Of the 36 biodiversity hotspots, regions with at least 1,500 endemic vascular plants that have lost at least 70 per cent of their original vegetation, India shares four: the Himalaya, Indo-Burma, the Western Ghats and Sri Lanka, and Sundaland through the Nicobar Islands. The Wildlife Institute of India divides the country into ten biogeographic zones, of which the Deccan Peninsula is the largest. Endemics such as the Nilgiri tahr, the lion-tailed macaque and the Sangai show how isolation breeds unique life.

Biodiversity matters for direct uses, such as food, timber and medicines like quinine and the periwinkle cancer drugs, and still more for ecosystem services, which the Millennium Ecosystem Assessment (2005) groups as provisioning, regulating, cultural and supporting. In Paul Ehrlich's rivet popper hypothesis, species play the part of the rivets fastening an aircraft: every one removed weakens the structure, and removing a keystone one can make it fail.

The main threats form Jared Diamond's evil quartet: habitats destroyed and broken into fragments, over-harvesting, invasive alien species, and co-extinction; pollution and climate change now add to them. Five mass extinctions are recorded, the end-Permian about 252 million years ago being the largest and the end-Cretaceous about 66 million years ago the best known. Many scientists speak of a sixth, driven by humans. India lost the cheetah, declared extinct in 1952, and reintroduced it at Kuno National Park in September 2022.

The IUCN Red List, kept since 1964 by the IUCN (founded 1948, Gland), places species in nine categories; only Critically Endangered, Endangered and Vulnerable count as threatened, and the list has no legal force. The great Indian bustard and gharial are Critically Endangered, the tiger Endangered and the one-horned rhino Vulnerable.

in situ conservation protects species where they live, through protected areas and community traditions such as sacred groves and the Bishnoi protection of khejri and blackbuck. ex situ conservation keeps them elsewhere: zoos, botanical gardens, captive breeding such as the vulture centre at Pinjore, seed and gene banks, and cryopreservation in liquid nitrogen. NBPGR in New Delhi runs the national gene bank, and the Svalbard vault in Norway backs up the world's seeds. BSI (1890) and ZSI (1916) count India's plants and animals, and the Biological Diversity Act, 2002 set up the National Biodiversity Authority in Chennai.

Biodiversity at a glance
TopicKey fact
LevelsGenetic, species, ecosystem (CBD 1992, Art 2)
MeasuresAlpha within, beta between, gamma regional (Whittaker)
IndiaOne of 17 megadiverse countries; about 2.4% of land, 7–8% of species
Hotspots36 worldwide; India's four: Himalaya, Indo-Burma, Western Ghats–Sri Lanka, Sundaland
Biogeographic zonesTen; Deccan Peninsula largest
ThreatsEvil quartet: habitat loss, overexploitation, invasive species, co-extinction
Red ListNine categories; CR, EN, VU are threatened
ConservationIn situ (protected areas, sacred groves); ex situ (zoos, gene banks, cryopreservation)

Exam traps

Recap

Practice questions

Q1. Different local varieties of rice grown across India are an example of

  1. Species diversity
  2. Genetic diversity
  3. Ecosystem diversity
  4. Gamma diversity
Show answer

Answer: B. Genetic diversity

Varieties of one species differ in their genes, so this is genetic diversity. Species diversity needs different species, ecosystem diversity different habitats, and gamma diversity is the total species diversity of a region.

Q2. Which one of the following regions of India is NOT part of a global biodiversity hotspot?

  1. Western Ghats
  2. Nicobar Islands
  3. Eastern Ghats
  4. North-east India
Show answer

Answer: C. Eastern Ghats

The Eastern Ghats are not a hotspot. The Western Ghats belong to the Western Ghats and Sri Lanka hotspot, the Nicobar Islands to Sundaland and the north-east to Indo-Burma.

Q3. Consider the following statements:
1. Of India's ten biogeographic zones, the Deccan Peninsula covers the largest area.
2. India's territory is roughly 2.4 per cent of the Earth's land surface.
Which of the statements given above is/are correct?

  1. 1 only
  2. 2 only
  3. Both 1 and 2
  4. Neither 1 nor 2
Show answer

Answer: C. Both 1 and 2

Both statements are correct, so options 1, 2 and 4 are wrong: the WII classification has ten zones with the Deccan Peninsula largest, and India has about 2.4 per cent of the world's land.

Q4. Pollination of crops by insects falls under which category of ecosystem services?

  1. Provisioning
  2. Regulating
  3. Cultural
  4. None of these
Show answer

Answer: B. Regulating

Pollination is a regulating service in the Millennium Ecosystem Assessment. Provisioning covers goods such as food and wood, cultural covers spiritual and recreational value, and 'none' is wrong because pollination is classed.

Q5. Which of the following is part of Jared Diamond's 'evil quartet' of causes of extinction?

  1. Ozone depletion
  2. Co-extinction
  3. Acid rain
  4. Volcanic eruptions
Show answer

Answer: B. Co-extinction

Co-extinction is the fourth member of the quartet, after habitat loss, overexploitation and invasive species. Ozone depletion and acid rain are forms of pollution, and volcanic eruptions are natural events; none of these is in the original four.

Q6. Consider the following statements about the IUCN Red List:
1. 'Near Threatened' is one of its threatened categories.
2. A species listed as 'Extinct in the Wild' survives only in captivity or cultivation.
Which of the statements given above is/are correct?

  1. 1 only
  2. 2 only
  3. Both 1 and 2
  4. Neither 1 nor 2
Show answer

Answer: B. 2 only

Statement 1 is wrong because only CR, EN and VU are threatened, which rules out options 1 and 3. Statement 2 is right, which rules out option 4.

Q7. Which of the following are methods of ex situ conservation?
1. Seed banks
2. Sacred groves
3. Cryopreservation
4. Botanical gardens
Select the correct answer using the code below.

  1. 1 and 2 only
  2. 1, 3 and 4 only
  3. 2 and 4 only
  4. 1, 2, 3 and 4
Show answer

Answer: B. 1, 3 and 4 only

Seed banks, cryopreservation and botanical gardens keep species outside their habitat. Sacred groves protect species in their natural home, so they are in situ; every option that includes 2 is wrong.

Q8. The idea of 'biodiversity hotspots' was first proposed in 1988 by

  1. Paul Ehrlich
  2. Norman Myers
  3. Jared Diamond
  4. David Tilman
Show answer

Answer: B. Norman Myers

Norman Myers proposed hotspots in 1988. Paul Ehrlich gave the rivet popper hypothesis, Jared Diamond the evil quartet, and David Tilman the grassland experiments on diversity and stability.

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