Lesson 12 of 12 · 12 min
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Must-know facts
20 facts
- 01Edward Wilson popularised the term biodiversity; its three key levels are genetic, species and ecological.
- 02Genetic diversity: Rauwolfia vomitoria (reserpine) across the Himalaya; India's 50,000+ rice strains and 1,000 mango varieties.
- 03Species diversity: Western Ghats have more amphibian species than the Eastern Ghats. Ecological: India more than Norway.
- 04IUCN (2004): slightly more than 1.5 million species described; Robert May's estimate about 7 million; extreme estimates 20-50 million.
- 05Recorded species: animals more than 70 per cent, plants no more than 22 per cent; insects more than 70 per cent of animals.
- 06Fungi outnumber fishes, amphibians, reptiles and mammals combined in species.
- 07India: 2.4 per cent of world land, 8.1 per cent of species; one of 12 mega diversity countries; about 45,000 plant species and twice as many animal species.
- 08Birds: Colombia nearly 1,400, New York (41° N) 105, Greenland (71° N) 56, India more than 1,200.
- 09Tropics are richer: more evolutionary time, a constant environment, more solar energy.
- 10log S = log C + Z log A; Z is 0.1-0.2 within regions, 0.6-1.2 for continents, 1.15 for frugivorous birds and mammals.
- 11Tilman: more species, less year-to-year variation in biomass and higher productivity.
- 12Rivet popper hypothesis: Paul Ehrlich; wing rivets are key species.
- 13IUCN Red List (2004): 784 extinctions in 500 years (338 vertebrates, 359 invertebrates, 87 plants); 27 species lost in the last twenty years.
- 14More than 15,500 species threatened: 12 per cent birds, 23 per cent mammals, 32 per cent amphibians, 31 per cent gymnosperms.
- 15The Sixth Extinction is 100 to 1,000 times faster than pre-human rates.
- 16Evil quartet: habitat loss and fragmentation (most important), over-exploitation, alien species invasions, co-extinctions.
- 17Nile perch in Lake Victoria: more than 200 cichlid species extinct.
- 1834 hotspots, three covering India: Western Ghats and Sri Lanka, Indo-Burma, Himalaya.
- 19India: 14 biosphere reserves, 90 national parks, 448 wildlife sanctuaries.
- 20Ex situ: zoos, botanical gardens, safari parks, cryopreservation, in vitro fertilisation, tissue culture, seed banks. Earth Summit Rio 1992; Johannesburg 2002 with 190 countries.
Common traps
Where marks are lost
Key terms
18 terms
- Biodiversity
- The combined variety of life at every level of biological organisation, from genes to biomes.
- Genetic diversity
- Variation within one species across its range, as in the reserpine content of Rauwolfia vomitoria.
- Species diversity
- The variety of species in a region, such as amphibians in the Western Ghats.
- Ecological diversity
- The variety of ecosystems in a region, such as India's deserts, forests, mangroves and reefs.
- Mega diversity country
- One of the 12 countries holding an exceptionally large share of the world's species; India is one.
- Latitudinal gradient
- The fall in species diversity from the equator towards the poles.
- Species-area relationship
- Species richness rises with area to a limit; log S = log C + Z log A.
- Z (regression coefficient)
- Slope of the log S against log A line; 0.1-0.2 within regions, 0.6-1.2 for continents.
- Rivet popper hypothesis
- Paul Ehrlich's analogy of species as rivets holding an airplane (the ecosystem) together.
- Evil quartet
- The four main causes of biodiversity loss: habitat loss and fragmentation, over-exploitation, alien invasions, co-extinctions.
- Co-extinction
- Extinction of species tied obligatorily to one that has gone extinct.
- Bioprospecting
- Exploring molecular, genetic and species diversity for products of economic importance.
- Endemism
- Species being confined to one region and found nowhere else.
- Biodiversity hotspot
- A region of very high species richness and endemism, chosen for maximum protection; there are 34.
- In situ conservation
- Protecting species in their natural habitat by protecting the whole ecosystem.
- Ex situ conservation
- Protecting threatened species away from their habitat, in zoos, gardens, seed banks or by cryopreservation.
- Sacred grove
- A forest tract protected by religious and cultural tradition, with all its trees and wildlife.
- Cryopreservation
- Keeping gametes viable and fertile for long periods at very low temperature.