Biodiversity and Conservation

The final chapter of the Ecology unit and one of the most dependable scorers in the whole Botany paper, worth 2 to 3 marks in almost every recent NEET. Nothing in this chapter was removed by the NCERT rationalisation, so the full surface is examinable, and almost all of it is asked close to NCERT wording. The chapter covers biodiversity as Edward Wilson defined it and its three levels - genetic diversity with Rauwolfia's reserpine and India's 50,000 rice strains, species diversity with the Western Ghats amphibians, and ecological diversity across deserts, rain forests, mangroves, coral reefs and alpine meadows; the global species accounting from the 1.5 million described to Robert May's estimate of 7 million, the share taken by animals, plants and insects, and India's 2.4 per cent of land area against 8.1 per cent of species; the two patterns of biodiversity - the latitudinal gradient with Colombia, New York and Greenland and the three reasons the tropics are richer, and Alexander von Humboldt's species-area relationship with its rectangular hyperbola, the equation log S = log C + Z log A and the Z values of 0.1 to 0.2 and 0.6 to 1.2; the importance of species diversity through David Tilman's outdoor plots and Paul Ehrlich's rivet popper hypothesis; the loss of biodiversity with the IUCN figure of 784 species, the dodo, quagga, thylacine and Steller's sea cow, the sixth extinction and its 100 to 1000 times faster rate; the Evil Quartet in full - habitat loss and fragmentation, over-exploitation, alien species invasions and co-extinctions; and conservation in both directions, the narrowly utilitarian, broadly utilitarian and ethical reasons, bioprospecting, in situ conservation with Norman Myers' hotspots, India's three hotspots, biosphere reserves, national parks, sanctuaries, Ramsar sites and sacred groves, ex situ conservation with zoos, botanical gardens, cryopreservation and seed banks, and the Rio 1992 and Johannesburg 2002 summits. Six graded practice sets, the last built entirely from genuine past-year NEET questions.