Unit 3: Biodiversity and conservation

Biodiversity (term coined by Walter G. Rosen, 1985; popularized by E.O. Wilson) is the variety and variability of life on Earth, measured across genes, species and ecosystems. It underpins the stability and productivity of the biosphere and every service humans draw from nature.

• Scope: Spans all organisms — microbes, plants, animals, fungi — and the ecological complexes they form.
• Measurement: Quantified as richness (number of types) and evenness (relative abundance).
• Distribution: Uneven globally; peaks in tropics, declines toward poles.
• Dynamic nature: Shaped by speciation, extinction, migration and human activity.

II. Levels of Biological Diversity

The three nested tiers at which variety is organised.

Biodiversity is conventionally described at three interlinked levels.

A. Genetic diversity

Variation in genes within a single species.

• Definition: Total number of genetic characteristics in the gene pool of a species.
• Basis: Alleles, mutations, recombination; e.g. India has ~50,000 genetically distinct rice varieties.
• Significance: Raises adaptability to disease and climate; low diversity risks inbreeding depression.

B. Species diversity

Variety of species within a region or community.

• Definition: Number and relative abundance of species in a defined area.
• Components: Richness (count) and evenness (distribution); measured by indices such as Simpson's or Shannon.
• Example: Western Ghats host far more amphibian species per km² than the Thar Desert.

C. Ecosystem diversity

Variety of habitats, communities and ecological processes.

• Definition: Diversity of ecosystems in a geographical unit — forests, wetlands, grasslands, coral reefs.
• Spatial terms: Alpha (within a habitat), beta (between habitats), gamma (landscape-wide).
• Significance: Sustains nutrient cycling, energy flow and habitat variety.

III. Importance of Biodiversity

Why biodiversity is valued — from life-support to inspiration.

Biodiversity delivers benefits classified into ecosystem services and several categories of value.

A. Ecosystem services

Benefits humans obtain from ecosystems (MEA, 2005 classification).

• Provisioning: Food, timber, fibre, medicines, fresh water.
• Regulating: Climate regulation, pollination, flood control, water purification.
• Supporting: Soil formation, nutrient cycling, primary production.
• Cultural: Recreation, spiritual and educational benefits.

B. Ecological value

The role of species in maintaining ecosystem function.

• Function: Producers, consumers and decomposers sustain energy flow and nutrient cycles.
• Keystone effect: Loss of one species (e.g. bees as pollinators) can collapse a whole community.

C. Economic value

Direct and indirect monetary benefits.

• Direct use: Crops, fisheries, timber, drugs; ~70% of anti-cancer drugs derive from natural sources.
• Indirect use: Pollination, soil fertility — services worth trillions of dollars annually.

D. Social value

Cultural and livelihood dependence on biodiversity.

• Livelihoods: Tribal and rural communities depend on forests for fuel, fodder, medicine.
• Cultural role: Sacred groves, worship of species like tulsi, peepal and cow in India.

E. Aesthetic value

The pleasure derived from natural beauty.

• Basis: Scenic landscapes, birdsong, wildlife photography, ecotourism.
• Example: Valley of Flowers and coral reefs attract visitors for their visual appeal.

F. Informational value

Biodiversity as a store of knowledge.

• Scientific: Genetic library for research, biomimicry and future medicines.
• Indicator: Species presence signals environmental health (e.g. lichens indicate clean air).

IV. Hot Spots of Biodiversity

Regions of exceptional richness under severe threat.

A biodiversity hotspot (concept by Norman Myers, 1988) is a priority region for conservation.

• Criteria: Must contain ≥1,500 endemic vascular plant species AND have lost ≥70% of original habitat.
• Global count: 36 recognised hotspots worldwide.
• Indian hotspots: Western Ghats–Sri Lanka, Himalaya, Indo-Burma, Sundaland (Nicobar Islands).
• Significance: Cover ~2.4% of land yet hold a large share of endemic species.

V. Threats to Biodiversity

The principal drivers of species and habitat decline.

Human pressures accelerate extinction far above natural background rates.

A. Habitat loss

Destruction, fragmentation and degradation of natural habitats.

• Cause: Deforestation, agriculture, urbanisation, dams, mining.
• Effect: Reduces population size and isolates species; leading cause of extinction.
• Example: Loss of grasslands threatens the Great Indian Bustard.

B. Poaching of wildlife

Illegal hunting and trade of species.

• Motives: Trade in ivory, rhino horn, tiger bones, musk, furs, skins.
• Impact: Directly reduces endangered populations; e.g. rhino poaching in Kaziranga.

C. Biological invasions

Introduction of alien species that outcompete natives.

• Mechanism: Invasive species lack natural predators and dominate resources.
• Examples: Lantana camara, water hyacinth (Eichhornia), African catfish in Indian waters.

D. Human-wildlife conflicts

Competition between people and wildlife over resources.

• Cause: Shrinking habitats push animals into farmland and settlements.
• Examples: Elephant crop raiding, leopard attacks near villages; leads to retaliatory killing.

VI. Species of Conservation Concern

IUCN Red List categories and priority-setting frameworks.

Species are classified by extinction risk to guide conservation action.

A. Extinct species

Species with no living individuals remaining.

• Definition: No reasonable doubt the last individual has died.
• Examples: Dodo, Indian cheetah (locally extinct until reintroduced).

B. Endangered species

Species facing very high risk of extinction in the wild.

• Definition: Severe population decline or restricted range.
• Examples: Bengal tiger, Asiatic lion, one-horned rhinoceros.

C. Vulnerable species

Species likely to become endangered unless threats abate.

• Definition: High risk over the medium term.
• Examples: Sloth bear, blackbuck, red panda.

D. Rare species

Species with small or localised populations.

• Definition: Not immediately threatened but at risk due to scarcity.
• Feature: Small populations concentrated in limited areas.

E. EDGE species

Evolutionarily Distinct and Globally Endangered species.

• Concept: Combines evolutionary uniqueness with extinction risk (ZSL programme).
• Examples: Gharial, pygmy hog, purple frog — few close relatives on the tree of life.

VII. Conservation Strategies

Two complementary approaches to protecting biodiversity.

Conservation is pursued either within or outside natural habitats.

A. In-situ conservation

Protection of species in their natural habitat.

1. Principle: Conserve whole ecosystems so species evolve naturally in situ.
2. Methods: Biosphere reserves, national parks, wildlife sanctuaries, sacred groves.
   • Examples: Corbett National Park, Nilgiri Biosphere Reserve; India has 18 biosphere reserves and 100+ national parks.
   • Advantage: Maintains natural interactions and evolutionary processes.

B. Ex-situ conservation

Protection of species outside their natural habitat.

1. Principle: Safeguard organisms in managed facilities when wild habitat is inadequate.
2. Methods: Zoos, botanical gardens, gene banks, seed banks, cryopreservation, tissue culture.
   • Examples: National Gene Bank (New Delhi), captive breeding of gharial and vultures.
   • Advantage: Enables breeding and later reintroduction; limited by space and gene pool size.

VIII. Biogeographic Zones of India

Regional division of India by climate, terrain and biota.

India is divided into ten biogeographic zones for conservation planning (Rodgers & Panwar, 1988).

• The ten zones:
  • Trans-Himalaya: Cold arid Ladakh; wild yak, snow leopard.
  • Himalaya: Alpine and temperate forests; red panda, musk deer.
  • Desert: Thar and Kutch; blackbuck, wild ass.
  • Semi-arid: Rajasthan–Gujarat scrub; lion, chinkara.
  • Western Ghats: High endemism; lion-tailed macaque, Nilgiri tahr.
  • Deccan Peninsula: Largest zone, deciduous forest; chital, sambar.
  • Gangetic Plain: Fertile alluvium; rhino, swamp deer.
  • North-East India: Rainforests; hoolock gibbon, clouded leopard.
  • Islands: Andaman & Nicobar, Lakshadweep; endemic corals, megapode.
  • Coasts: Mangroves and beaches; olive ridley turtle, dugong.

IX. India as a Mega-diversity Nation

India's global standing in biodiversity wealth.

India is one of 17 identified megadiverse countries (Conservation International), holding a disproportionate share of global species.

• Global share: ~2.4% of world's land area but ~7–8% of recorded species.
• Species count: Over 45,000 plant and 91,000 animal species documented.
• Endemism: High endemism in Western Ghats, Himalaya and the islands.
• Ecosystem range: Spans deserts, rainforests, wetlands, coral reefs and alpine meadows.
• Cultural depth: Long tradition of nature worship and agrobiodiversity — thousands of indigenous crop and livestock breeds.
• Legal framework: Wildlife Protection Act (1972) and Biological Diversity Act (2002) support conservation.