Biodiversity and Conservation — Long Notes
Biodiversity is the variety and variability of all life on Earth — from the tiniest bacterium to the tallest tree, from genes to entire ecosystems. The term was popularised by ecologist Edward Wilson in the 1980s.
1. Levels of Biodiversity
Biodiversity is measured at three interlinked levels:
1.1 Genetic Diversity
- Variation within a species.
- Example: Rauwolfia serpentina in different Himalayan ranges shows varying concentrations of the medicinal alkaloid reserpine.
- India has over 50,000 different rice varieties — a huge genetic reservoir.
1.2 Species Diversity
- Number and richness of species in a region.
- Example: Western Ghats have more amphibian species than the Eastern Ghats.
1.3 Ecological / Ecosystem Diversity
- Variety of ecosystems in a region.
- India shows spectacular ecosystem diversity — deserts (Thar), rainforests (Western Ghats), coral reefs (Andaman), mangroves (Sundarbans), tundra-like conditions (Ladakh).
2. How Much Biodiversity Exists?
- About 1.5 million species have been formally described so far.
- Robert May estimated the total (including undiscovered) at about 7 million.
- Rough composition:
- Animals ~70% of described species.
- Plants (incl. algae, fungi) ~22%.
- Remainder — prokaryotes, protists (probably vastly underestimated because many can't be cultured).
- Insects alone account for ~70% of all animal species.
- Fungi outnumber vertebrate species.
- India has only 2.4% of world's land area but contributes ~8% of world's species — a mega-diverse country.
3. Patterns of Biodiversity
3.1 Latitudinal Gradient
Species richness generally decreases from the equator toward the poles.
- Colombia (~4°N) — nearly 1400 bird species.
- New York (41°N) — ~105.
- Greenland (71°N) — ~56.
Reasons proposed:
- Tropics have been climatically stable for longer, allowing more time for speciation.
- Higher solar input → higher productivity → more energy in the food web.
- Less seasonal glaciation disturbs communities.
- Tropical niches are narrower and more specialised.
3.2 Species-Area Relationship
Species richness increases with area, then plateaus.
- Formulated by Alexander von Humboldt.
- Equation: S = CA^Z
- On log-log scale: log S = log C + Z log A — a straight line.
- Slope Z: 0.1–0.2 for small areas within a region; 0.6–1.2 for very large areas across continents (Rosenzweig).
4. Importance of Species Diversity to the Ecosystem
- Ecologists like David Tilman experimentally showed that communities with more species show:
- Less variation in productivity year to year.
- Higher productivity overall.
- Greater resistance to biological invasions.
- Paul Ehrlich's Rivet-Popper Hypothesis: an aeroplane has thousands of rivets, and although losing one may not doom the flight, losing many rivets increases risk of catastrophic failure. Species in ecosystems are like the rivets — the loss of species eventually compromises ecosystem function.
5. Loss of Biodiversity
Extinction is natural, but current extinction rates are 100–1000 times the natural background rate. We are in a sixth mass extinction.
Since 1500 AD:
- 338 vertebrates, 361 invertebrates, and 87 plants are documented as extinct.
- Notable extinctions: dodo (Mauritius, 17th century), quagga (Africa), thylacine (Australia), Steller's sea cow, three subspecies of tiger (Bali, Javan, Caspian).
- The IUCN Red List (2004) listed ~15,500 threatened species.
5.1 Causes of Biodiversity Loss — HIPPO
- Habitat loss and fragmentation — the single biggest cause. Amazon rainforest ("lungs of the planet") is being felled for cattle ranching and soy; wetlands are being drained.
- Invasive alien species — non-native species that outcompete natives. Examples:
- Lantana — invasive shrub.
- **Water hyacinth (Eichhornia crassipes)** — clogs Indian water bodies.
- **African catfish (Clarias gariepinus)** — introduced into Indian rivers; endangers native species.
- Pollution — chemical, plastic, noise, light pollution.
- Population growth — human population intensifies pressure on all resources.
- Overexploitation — many fisheries have collapsed (steller's sea cow); poaching for horns, ivory, skins.
Co-extinctions: When a host species dies, its obligate parasites also die (e.g. parasitic bird lice that lived exclusively on the passenger pigeon).
6. Why Should We Conserve Biodiversity?
Three broad reasons:
6.1 Narrowly Utilitarian
- Direct economic benefits — food, firewood, timber, fibre, industrial products.
- Medicines: over 25% of drugs in market come from plants; taxol (anti-cancer) from Taxus; quinine (anti-malarial) from Cinchona; reserpine (BP) from Rauwolfia.
- Countless yet-to-be-discovered products.
6.2 Broadly Utilitarian (Ecosystem Services)
- ~20% of the world's oxygen is produced by the Amazon rainforest alone.
- Water cycle, pollination, seed dispersal, soil formation, carbon sequestration.
- Climate regulation (forests moderate temperatures and rainfall).
- Aesthetic pleasure — bird-watching, hiking, ecotourism.
6.3 Ethical
- Each species has an intrinsic right to exist, independent of its use to humans.
- We have a moral duty to hand over Earth's biological heritage to future generations.
7. How Do We Conserve Biodiversity?
Two main strategies: in-situ and ex-situ.
7.1 In-situ Conservation (in the natural habitat)
Biodiversity Hotspots — areas with high species richness + high endemism + severe threat. Norman Myers identified them.
- 34 hotspots globally.
- India has 3:
- Western Ghats + Sri Lanka.
- Eastern Himalayas.
- Indo-Burma.
Protected areas in India:
- Biosphere Reserves — 18 (e.g. Nilgiri, Sundarbans, Nanda Devi, Nokrek).
- National Parks — over 100 (Jim Corbett, Kanha, Kaziranga, Ranthambore).
- Wildlife Sanctuaries — over 500 (many state-run).
Sacred groves — patches of forest protected by local communities on religious grounds.
- Khasi & Jaintia Hills (Meghalaya) — famous sacred groves.
- Aravalli Hills (Rajasthan).
- Western Ghats — Karnataka & Maharashtra.
- Sarpakavus (Kerala) — snake groves.
Traditional beliefs have thus preserved species that would otherwise be gone.
7.2 Ex-situ Conservation (outside natural habitat)
For species that need special protection:
- Zoological parks (zoos) — captive breeding of endangered animals.
- Botanical gardens — living collections of rare plants.
- Wildlife safaris.
- Seed banks — long-term storage of seeds (e.g. Svalbard, Norway).
- Gene banks — freeze pollen, gametes, DNA of threatened species.
- Tissue culture — micropropagation for propagation and preservation.
- Cryopreservation at −196°C (liquid nitrogen) — preserves seeds, embryos, sperm indefinitely.
8. International Efforts
- Earth Summit, Rio de Janeiro (1992) — the Convention on Biological Diversity (CBD) was adopted. Three main goals: conservation of biodiversity, sustainable use, and fair sharing of benefits from genetic resources.
- World Summit on Sustainable Development, Johannesburg (2002) — 190 countries pledged to achieve a significant reduction in the rate of biodiversity loss by 2010.
- Later: Aichi Biodiversity Targets, Kunming-Montreal Global Biodiversity Framework.
Key take-aways
- Biodiversity spans genetic, species, and ecosystem levels; species diversity is the most commonly measured layer.
- ~1.5 million species described; total estimate by Robert May ~7 million; insects dominate.
- Tropics are richest — latitudinal gradient and species-area relationship are two classical patterns.
- Communities with more species are more productive and stable — supported by Tilman's data and Ehrlich's rivet analogy.
- The sixth mass extinction is human-driven — HIPPO: Habitat loss, Invasive species, Pollution, Population, Overexploitation.
- Conservation combines in-situ (biosphere reserves, national parks, wildlife sanctuaries, sacred groves, hotspots) and ex-situ (zoos, botanical gardens, seed & gene banks, cryopreservation).
- Biodiversity is a global commons; international agreements like the CBD anchor collaborative action.
Biodiversity and Conservation — Long Notes
Biodiversity is the variety and variability of all life on Earth — from the tiniest bacterium to the tallest tree, from genes to entire ecosystems. The term was popularised by ecologist Edward Wilson in the 1980s.
1. Levels of Biodiversity
Biodiversity is measured at three interlinked levels:
1.1 Genetic Diversity
- Variation within a species.
- Example: Rauwolfia serpentina in different Himalayan ranges shows varying concentrations of the medicinal alkaloid reserpine.
- India has over 50,000 different rice varieties — a huge genetic reservoir.
1.2 Species Diversity
- Number and richness of species in a region.
- Example: Western Ghats have more amphibian species than the Eastern Ghats.
1.3 Ecological / Ecosystem Diversity
- Variety of ecosystems in a region.
- India shows spectacular ecosystem diversity — deserts (Thar), rainforests (Western Ghats), coral reefs (Andaman), mangroves (Sundarbans), tundra-like conditions (Ladakh).
2. How Much Biodiversity Exists?
- About 1.5 million species have been formally described so far.
- Robert May estimated the total (including undiscovered) at about 7 million.
- Rough composition:
- Animals ~70% of described species.
- Plants (incl. algae, fungi) ~22%.
- Remainder — prokaryotes, protists (probably vastly underestimated because many can't be cultured).
- Insects alone account for ~70% of all animal species.
- Fungi outnumber vertebrate species.
- India has only 2.4% of world's land area but contributes ~8% of world's species — a mega-diverse country.
3. Patterns of Biodiversity
3.1 Latitudinal Gradient
Species richness generally decreases from the equator toward the poles.
- Colombia (~4°N) — nearly 1400 bird species.
- New York (41°N) — ~105.
- Greenland (71°N) — ~56.
Reasons proposed:
- Tropics have been climatically stable for longer, allowing more time for speciation.
- Higher solar input → higher productivity → more energy in the food web.
- Less seasonal glaciation disturbs communities.
- Tropical niches are narrower and more specialised.
3.2 Species-Area Relationship
Species richness increases with area, then plateaus.
- Formulated by Alexander von Humboldt.
- Equation: S = CA^Z
- On log-log scale: log S = log C + Z log A — a straight line.
- Slope Z: 0.1–0.2 for small areas within a region; 0.6–1.2 for very large areas across continents (Rosenzweig).
4. Importance of Species Diversity to the Ecosystem
- Ecologists like David Tilman experimentally showed that communities with more species show:
- Less variation in productivity year to year.
- Higher productivity overall.
- Greater resistance to biological invasions.
- Paul Ehrlich's Rivet-Popper Hypothesis: an aeroplane has thousands of rivets, and although losing one may not doom the flight, losing many rivets increases risk of catastrophic failure. Species in ecosystems are like the rivets — the loss of species eventually compromises ecosystem function.
5. Loss of Biodiversity
Extinction is natural, but current extinction rates are 100–1000 times the natural background rate. We are in a sixth mass extinction.
Since 1500 AD:
- 338 vertebrates, 361 invertebrates, and 87 plants are documented as extinct.
- Notable extinctions: dodo (Mauritius, 17th century), quagga (Africa), thylacine (Australia), Steller's sea cow, three subspecies of tiger (Bali, Javan, Caspian).
- The IUCN Red List (2004) listed ~15,500 threatened species.
5.1 Causes of Biodiversity Loss — HIPPO
- Habitat loss and fragmentation — the single biggest cause. Amazon rainforest ("lungs of the planet") is being felled for cattle ranching and soy; wetlands are being drained.
- Invasive alien species — non-native species that outcompete natives. Examples:
- Lantana — invasive shrub.
- **Water hyacinth (Eichhornia crassipes)** — clogs Indian water bodies.
- **African catfish (Clarias gariepinus)** — introduced into Indian rivers; endangers native species.
- Pollution — chemical, plastic, noise, light pollution.
- Population growth — human population intensifies pressure on all resources.
- Overexploitation — many fisheries have collapsed (steller's sea cow); poaching for horns, ivory, skins.
Co-extinctions: When a host species dies, its obligate parasites also die (e.g. parasitic bird lice that lived exclusively on the passenger pigeon).
6. Why Should We Conserve Biodiversity?
Three broad reasons:
6.1 Narrowly Utilitarian
- Direct economic benefits — food, firewood, timber, fibre, industrial products.
- Medicines: over 25% of drugs in market come from plants; taxol (anti-cancer) from Taxus; quinine (anti-malarial) from Cinchona; reserpine (BP) from Rauwolfia.
- Countless yet-to-be-discovered products.
6.2 Broadly Utilitarian (Ecosystem Services)
- ~20% of the world's oxygen is produced by the Amazon rainforest alone.
- Water cycle, pollination, seed dispersal, soil formation, carbon sequestration.
- Climate regulation (forests moderate temperatures and rainfall).
- Aesthetic pleasure — bird-watching, hiking, ecotourism.
6.3 Ethical
- Each species has an intrinsic right to exist, independent of its use to humans.
- We have a moral duty to hand over Earth's biological heritage to future generations.
7. How Do We Conserve Biodiversity?
Two main strategies: in-situ and ex-situ.
7.1 In-situ Conservation (in the natural habitat)
Biodiversity Hotspots — areas with high species richness + high endemism + severe threat. Norman Myers identified them.
- 34 hotspots globally.
- India has 3:
- Western Ghats + Sri Lanka.
- Eastern Himalayas.
- Indo-Burma.
Protected areas in India:
- Biosphere Reserves — 18 (e.g. Nilgiri, Sundarbans, Nanda Devi, Nokrek).
- National Parks — over 100 (Jim Corbett, Kanha, Kaziranga, Ranthambore).
- Wildlife Sanctuaries — over 500 (many state-run).
Sacred groves — patches of forest protected by local communities on religious grounds.
- Khasi & Jaintia Hills (Meghalaya) — famous sacred groves.
- Aravalli Hills (Rajasthan).
- Western Ghats — Karnataka & Maharashtra.
- Sarpakavus (Kerala) — snake groves.
Traditional beliefs have thus preserved species that would otherwise be gone.
7.2 Ex-situ Conservation (outside natural habitat)
For species that need special protection:
- Zoological parks (zoos) — captive breeding of endangered animals.
- Botanical gardens — living collections of rare plants.
- Wildlife safaris.
- Seed banks — long-term storage of seeds (e.g. Svalbard, Norway).
- Gene banks — freeze pollen, gametes, DNA of threatened species.
- Tissue culture — micropropagation for propagation and preservation.
- Cryopreservation at −196°C (liquid nitrogen) — preserves seeds, embryos, sperm indefinitely.
8. International Efforts
- Earth Summit, Rio de Janeiro (1992) — the Convention on Biological Diversity (CBD) was adopted. Three main goals: conservation of biodiversity, sustainable use, and fair sharing of benefits from genetic resources.
- World Summit on Sustainable Development, Johannesburg (2002) — 190 countries pledged to achieve a significant reduction in the rate of biodiversity loss by 2010.
- Later: Aichi Biodiversity Targets, Kunming-Montreal Global Biodiversity Framework.
Key take-aways
- Biodiversity spans genetic, species, and ecosystem levels; species diversity is the most commonly measured layer.
- ~1.5 million species described; total estimate by Robert May ~7 million; insects dominate.
- Tropics are richest — latitudinal gradient and species-area relationship are two classical patterns.
- Communities with more species are more productive and stable — supported by Tilman's data and Ehrlich's rivet analogy.
- The sixth mass extinction is human-driven — HIPPO: Habitat loss, Invasive species, Pollution, Population, Overexploitation.
- Conservation combines in-situ (biosphere reserves, national parks, wildlife sanctuaries, sacred groves, hotspots) and ex-situ (zoos, botanical gardens, seed & gene banks, cryopreservation).
- Biodiversity is a global commons; international agreements like the CBD anchor collaborative action.