Chapter 13: Biodiversity and Conservation

Introduction

Overview

• Earth hosts vast life diversity: 20,000+ ant species, 300,000 beetles, 28,000 fishes, 20,000 orchids.

Memory Aids

• Remember: Ants and beetles dominate insect diversity.

Quick Checkpoints

• What are examples of species diversity on Earth?

Biodiversity

Definition and Levels

• Biodiversity: Variety of ecosystems, species, biotypes, and genes with interactions.
• Term coined by Walter G. Rosen (1985), popularised by Edward Wilson (1992).
• Varies by environment and species tolerance.
• Described species: ~1.5 million; estimated total species: ~7 million (Robert May).
• Three levels: Genetic, Species, Ecological diversity.
• Ecological diversity types: Alpha (within habitat), Beta (between habitats), Gamma (across regions).

Memory Aids

• Alpha = local diversity, Beta = habitat difference, Gamma = regional diversity.

Quick Checkpoints

• What are the three hierarchical levels of biodiversity?
• Define alpha, beta, and gamma diversity.

Global Species Distribution

Key Facts

• Animals: >70% of species; plants: ~22%.
• Insects: >70% of animal species.
• Fungi species outnumber fishes, amphibians, reptiles, mammals combined.
• India: 2.4% land area, 8.1% global species diversity; one of 12 mega-diversity countries.
• India's biogeographical regions: 10 distinct zones.
• Recorded species in India: ~45,000 plants, double animals.
• Estimated undiscovered species: >100,000 plants, >300,000 animals.
• Endemic species: confined to specific regions (e.g., Western Ghats amphibians).

Memory Aids

• India: Small land, big biodiversity.
• Insects dominate animal diversity.

Quick Checkpoints

• What percentage of global species diversity does India hold?
• Which group forms the largest proportion of animal species?

Patterns of Biodiversity

Latitudinal Gradients

• Species diversity decreases from equator to poles.
• Tropics (23.5°N to 23.5°S) have highest species richness.
• Examples: Colombia (~1,400 bird species), New York (105), Greenland (56).
• Amazon rainforest: richest biodiversity globally.
• Hypotheses for tropical diversity:
  • Long evolutionary time (less glaciation).
  • Stable, less seasonal environment promotes niche specialization.
  • Higher solar energy increases productivity and diversity.

Species-Area Relationship

• Species richness increases with area but plateaus.
• Relationship: log S = log C + z log A (S=species, A=area).
• Z value: 0.1-0.2 generally; higher for continents (0.6-1.2).

Memory Aids

• More area = more species (up to a limit).
• Tropics = species hotspot.

Quick Checkpoints

• Why does species diversity decrease towards poles?
• Explain the species-area relationship.

Importance of Species Diversity

Key Points

• Ecological stability: Diverse ecosystems resist stress better.
• Higher productivity in biodiverse ecosystems.
• Maintains ecosystem health via checks, feedbacks, keystone species.
• Rivet popper hypothesis: Loss of species weakens ecosystem like rivets in a plane.

Memory Aids

• More species = stronger ecosystem.
• Rivet analogy: Each species vital for ecosystem safety.

Quick Checkpoints

• How does species diversity contribute to ecosystem stability?
• What is the rivet popper hypothesis?

Loss of Biodiversity

Overview

• Rapid decline due to human activities.
• IUCN Red List (2004): 784 species extinct in last 500 years.
• 15,500+ species currently threatened.
• Extinction rates 100-1,000 times faster than pre-human times.
• Five mass extinctions in Earth's history; current trend alarming.

Memory Aids

• Extinction types: Natural, Mass, Anthropogenic.
• Current extinction mainly anthropogenic.

Quick Checkpoints

• What are the three types of extinction?
• Why is current extinction rate alarming?

Causes of Biodiversity Loss

The Evil Quartet

• Habitat loss and fragmentation: Main cause; reduces shelter, increases predation, disrupts species interactions.
• Over-exploitation: Excessive hunting/fishing reduces populations, leading to extinction.
• Alien species invasion: Non-native species outcompete natives, causing declines.
• Co-extinction: Extinction of one species causes dependent species to vanish.

Other Causes

• Disturbance and degradation: Fires, pest attacks, human clearing.
• Pollution: Pesticides cause biomagnification; heavy metals and oil spills harm species.
• Intensive agriculture: Habitat destruction and reduced genetic diversity.
• Forestry: Monocultures reduce species diversity and increase vulnerability.

Memory Aids

• Remember "Evil Quartet": Habitat loss, Over-exploitation, Alien invasion, Co-extinction.

Quick Checkpoints

• List the four major causes of biodiversity loss.
• How does habitat fragmentation affect species?

Red List Categories

Definitions

• Extinct: Species completely gone (e.g., Dodo).
• Critically Endangered: Very high risk of extinction soon (e.g., Pigmy Hog).
• Endangered: High risk of extinction in near future (e.g., Lion-tailed Macaque).
• Vulnerable: Population declining, risk in medium term (e.g., Clouded Leopard).
• Extinct in Wild: Only survives in captivity.
• Lower Risk: Threatened but stable.
• Data Deficient: Insufficient data to assess risk.
• Rare Species: Naturally small populations, vulnerable.
• Not Evaluated: No assessment done.
• Indeterminate: At risk, cause unknown.

Memory Aids

• Extinct = gone; Critically Endangered = immediate risk.
• Endangered and Vulnerable = declining populations.

Quick Checkpoints

• What category describes species extinct in the wild?
• Define Critically Endangered and Vulnerable categories.

Biodiversity Conservation

Concept and Importance

• Protection and scientific management of biodiversity to maintain optimal levels for sustainable benefits.
• Reasons to conserve biodiversity:
  • Narrowly utilitarian: Direct economic benefits like food, medicine, industrial products; over 25% of drugs are plant-derived.
  • Broadly utilitarian: Ecosystem services like oxygen production, pollination, and aesthetic value.
  • Ethical: Every species has intrinsic value beyond economic use.
• Red List Purpose: Awareness of threat levels, global biodiversity index, identify species at extinction risk, set conservation priorities, inform international agreements like CBD and CITES.

Memory Aids

• 3 reasons to conserve: Narrow, Broad, Ethical (NBE).
• Red List = Risk awareness + Conservation priority.

Quick Checkpoints

• What are the three categories of reasons to conserve biodiversity?
• What is the main purpose of the Red List?
• Give examples of economic benefits from biodiversity.

Conservation Strategies

Types and Methods

• In-situ Conservation: Protecting species in natural habitats; includes hotspots and protected areas.
• Ex-situ Conservation: Protecting species outside natural habitats; includes seed banks, gene banks, botanical gardens, zoos.

Memory Aids

• In-situ = "In place"; Ex-situ = "Out of place" conservation.
• In-situ protects ecosystems; Ex-situ preserves genetic material.

Quick Checkpoints

• Define in-situ and ex-situ conservation.
• List examples of in-situ conservation areas.
• What are gene banks used for?

In-situ Conservation

Details and Examples

• Conservation of ecosystems and biodiversity in natural habitats.
• Includes:
  • Hotspots: Areas rich in endemic species but vulnerable; 34 globally, 3 in India.
  • Protected Areas:
    • National Parks: Strict protection, no farming or grazing.
    • Biosphere Reserves: UNESCO designated; zones - Core (no human activity), Buffer (limited research), Transition (sustainable use).
    • Sanctuaries: Protect animals, allow limited human use like grazing.
• India's sacred groves protect rare species; examples include Khasi Hills, Aravalli Hills, Western Ghats.
• Religious traditions aid conservation (e.g., Bishnois protect Prosopis cineraria and Black Buck).

Memory Aids

• Hotspots = High diversity + High threat.
• Biosphere Reserve zones: Core (strict), Buffer (limited), Transition (sustainable).
• Sanctuaries allow some human activity; National Parks do not.

Quick Checkpoints

• What defines a biodiversity hotspot?
• Difference between National Parks and Sanctuaries?
• What are the three zones of a Biosphere Reserve?

Ex-situ Conservation

Methods and Applications

• Conservation outside natural habitats; includes offsite collections and gene banks.
• Offsite collections: Botanical gardens, zoos, wildlife parks breed and maintain species; some released back to wild.
• Gene banks: Preserve seeds, live plants, genetic material with diversity.
• Seed types:
  • Orthodox seeds: Can be dried and stored cold (e.g., cereals, legumes).
  • Recalcitrant seeds: Cannot tolerate drying/cold (e.g., cocoa, coconut).
• Orchards maintain plants with recalcitrant seeds (e.g., litchi, oil palm).
• Tissue culture: Multiplication of plants from parts like pollen or embryos; useful for seedless or endangered plants.
• Cryopreservation: Freezing cells/tissues at -196°C for indefinite preservation; revivable when needed.

Memory Aids

• Offsite = Botanical gardens + Zoos; Gene banks = Seed + Tissue storage.
• Orthodox seeds = Dry + Cold tolerant; Recalcitrant = Sensitive.
• Tissue culture and cryopreservation aid rapid multiplication and long-term storage.

Quick Checkpoints

• What is the difference between orthodox and recalcitrant seeds?
• List two methods of ex-situ conservation.
• What is cryopreservation used for?

International Efforts

Key Agreements and Organisations

• Earth Summit (1992): Promoted Convention on Biological Diversity (CBD); signed by 152 nations; India joined in 1994.
• Commitments:
  • Conserve biodiversity.
  • Manage biodiversity sustainably.
  • Equitable sharing of benefits from genetic resources.
• Earth Summit (Rio+20, 2012): New sustainable development strategies.
• Agenda 21: Blueprint for sustainable development in 21st century.
• World Conservation Union (IUCN): Leadership in conservation.
• World Wide Fund for Nature (WWF): International conservation support.
• CITES: Restricts trade in endangered species; helped save elephants.
• UNESCO MAB Programme: Supports biosphere reserves.

Memory Aids

• CBD = Conservation + Sustainable use + Benefit sharing.
• CITES = Trade control to protect species.
• Agenda 21 = 21st-century sustainability plan.

Quick Checkpoints

• What are the main goals of the Convention on Biological Diversity?
• Which organisation restricts international trade of endangered species?
• What is the purpose of Agenda 21?

Biodiversity Conservation in India

National Initiatives

• In-situ conservation managed by Ministry of Environment and Forests.
• Ex-situ conservation managed by National Bureau of Plant, Animal and Fish Genetic Resources.
• International Crop Research Institute for Semi-Arid Tropics (ICRISAT), Hyderabad conserves germplasm of crops like groundnut, pigeon pea, chickpea, pearl millet, sorghum.
• Multiple centres maintain diverse crop varieties for conservation.

Memory Aids

• ICRISAT = Crop germplasm conservation in semi-arid tropics.
• Ministry of Environment = In-situ; National Bureau = Ex-situ.

Quick Checkpoints

• Which Indian institute conserves crop germplasm for semi-arid tropics?
• Who manages in-situ conservation in India?
• What is the role of the National Bureau of Plant, Animal and Fish Genetic Resources?