Biodiversity and Conservation

Biodiversity is the variety of life at every level of biological organisation, and this chapter examines it at three levels named by Edward Wilson: genetic diversity, such as the variation in reserpine content among Rauwolfia vomitoria populations of the Himalayas, species diversity, such as the higher amphibian diversity of the Western Ghats compared with the Eastern Ghats, and ecological diversity, from deserts to mangroves. You will learn that about 1.5 million species have been described, that Robert May estimated the global total at about 7 million, and that India, with only 2.4% of the world's land area, holds 8.1% of global species diversity, making it one of the 12 mega diversity countries. The chapter explains patterns of biodiversity, including the latitudinal gradient and Alexander von Humboldt's species-area relationship, log S = log C + Z log A. It also covers why biodiversity matters, the rivet popper hypothesis, the evil quartet causing extinction (habitat loss and fragmentation, over-exploitation, alien species invasions and co-extinctions), and in situ and ex situ conservation such as hotspots, sacred groves and seed banks.

Detailed Worksheet: Biodiversity and Conservation Section A - Definitions (10 marks) 1. Define biodiversity. Name the three levels of biodiversity described by Edward Wilson with one example of each from India. (2 marks) 2. What is meant by the latitudinal gradient in species diversity? Give one example with figures. (2 marks) 3. State the species-area relationship proposed by Alexander von Humboldt, and write its logarithmic form. (2 marks) 4. What are biodiversity hotspots? Name the three hotspots that cover India's biodiversity-rich regions. (2 marks) 5. Distinguish between in situ and ex situ conservation, with two examples of each. (2 marks) Section B - Calculations and Applications (15 marks) 6. In a region, the species-area relationship has Z = 0.2. Using log S = log C + Z log A, calculate by what factor species richness increases when the area sampled becomes 32 times larger. Explain why Z is much higher when very large areas such as entire continents are considered. (3 marks) 7. The IUCN Red List (2004) documents the extinction of 784 species in the last 500 years, including 338 vertebrates, 359 invertebrates and 87 plants. Calculate the percentage of each group in the total, and suggest one reason why the number of extinct invertebrates may be an underestimate. (3 marks) 8. Robert May estimated that only about 22% of the total species on Earth have been recorded. India has about 45,000 recorded plant species. Using May's proportion, estimate the total number of plant species likely to exist in India and the number yet to be discovered. Show your working. (3 marks) 9. Tropical rainforests once covered about 14% of the Earth's land surface and now cover no more than 6%. Calculate the percentage loss of the original rainforest cover, and name two consequences of this loss. (3 marks) 10. Apply the evil quartet to identify the cause of loss in each case: (i) extinction of more than 200 cichlid species in Lake Victoria after introduction of the Nile perch (ii) extinction of Steller's sea cow and the passenger pigeon (iii) death of parasites unique to a host fish when the host becomes extinct. (3 marks) Section C - Diagrams (10 marks) 11. Draw a graph showing the species-area relationship on a normal scale and on a log-log scale. Label the axes, the curve and the slope Z, and state the usual range of Z values. (4 marks) 12. Draw a labelled pie chart showing the global diversity of invertebrates, vertebrates and plants, indicating which group (insects) has the largest share. (3 marks) 13. Draw a labelled diagram of a biosphere reserve showing the core zone, buffer zone and transition zone, and state the permitted activities in each. (3 marks) Section D - Analysis and Higher-order Thinking (15 marks) 14. Explain three hypotheses proposed to explain why tropical regions have greater biodiversity than temperate regions. Use the example of Colombia, New York and Greenland bird species to support your answer. (5 marks) 15. Paul Ehrlich compared species in an ecosystem to rivets in an aeroplane. Explain the rivet popper hypothesis, and use David Tilman's long-term ecosystem experiments to analyse why loss of species diversity can reduce the stability and productivity of an ecosystem. (5 marks) 16. A state government plans to clear a sacred grove to build a highway. Evaluate this proposal using the narrowly utilitarian, broadly utilitarian and ethical arguments for conserving biodiversity, and name two Indian regions where sacred groves are found. (5 marks) Instructions: Time allowed 2 hours. Attempt all sections. Draw diagrams and graphs neatly with labelled axes, and give Indian examples wherever possible.