Unit 3: Biodiversity and conservation - Subjective Questions

Biodiversity (biological diversity) refers to the variety and variability of life forms on Earth, including the diversity within species, between species, and of ecosystems. The term was popularized by E.O. Wilson.

The three levels of biological diversity are:

• Genetic Diversity: Variation of genes within a species. Example: Different varieties of rice (over 50,000 varieties in India) or different breeds of dogs.
• Species Diversity: Variety of species within a region. Example: The Western Ghats support thousands of plant and animal species. It includes species richness (number of species) and species evenness (relative abundance).
• Ecosystem Diversity: Variety of ecosystems in a geographical area such as forests, wetlands, deserts, grasslands, and coral reefs.

These levels are interconnected and together determine the ecological stability of the planet.

Genetic diversity refers to the variation in genes and genotypes within a single species. It arises due to mutation, gene flow, sexual reproduction, and recombination.

Significance:

• Adaptation: A genetically diverse population can adapt better to changing environmental conditions.
• Resistance to Disease: Diverse gene pools reduce the risk of entire populations being wiped out by disease or pests.
• Evolutionary Potential: Provides raw material for natural selection and evolution.
• Agricultural Value: Crop wild relatives provide genes for improving yield, disease resistance, and drought tolerance.
• Survival in Extreme Conditions: Populations with low genetic diversity (inbreeding) face higher extinction risk.

Example: The genetic variation among different varieties of wheat allowed scientists to develop high-yielding, disease-resistant strains during the Green Revolution.

Species diversity is measured using two key components:

Illustration: Two communities may have the same number of species (equal richness), but if one is dominated by a single species while the other has evenly distributed populations, the latter has higher evenness and thus greater overall diversity.

Biodiversity provides multiple benefits categorized as follows:

Ecological Value:

• Maintains ecological balance and stability.
• Supports food chains, food webs, and nutrient cycling.
• Provides ecosystem services like pollination, climate regulation, and pest control.

Economic Value:

• Source of food, medicines, timber, fibre, and raw materials for industries.
• Supports agriculture, fisheries, and tourism.
• Consumptive value (directly consumed goods like fuelwood, food) and productive value (commercially traded products).

Social Value:

• Deeply linked with the customs, religion, and traditions of indigenous communities.
• Many plants and animals are considered sacred (e.g., Tulsi, Peepal, cow).
• Preserves traditional knowledge systems.

Thus biodiversity is fundamental to both human welfare and the healthy functioning of the biosphere.

Ecosystem services are the benefits that humans obtain freely from natural ecosystems. The Millennium Ecosystem Assessment classifies them into four categories:

• Provisioning Services: Products obtained from ecosystems.
  • Examples: Food, fresh water, timber, fibre, medicines, fuelwood.
• Regulating Services: Benefits from regulation of ecosystem processes.
  • Examples: Climate regulation, flood control, water purification, pollination, disease control.
• Cultural Services: Non-material benefits.
  • Examples: Recreation, aesthetic enjoyment, spiritual value, ecotourism, education.
• Supporting Services: Services necessary for producing all other services.
  • Examples: Nutrient cycling, soil formation, photosynthesis, primary production.

These services are essential for human survival and are estimated to be worth trillions of dollars annually.

Aesthetic Value:

• Refers to the beauty and pleasure that nature provides to humans.
• The scenic beauty of forests, mountains, wildlife, and landscapes offers recreation and mental relaxation.
• Forms the basis of ecotourism and wildlife tourism, which generate revenue.
• Examples: Bird watching, safari tours, visiting national parks and botanical gardens.

Informational Value:

• Biodiversity acts as a vast reservoir of scientific information.
• Each species carries genetic information developed over millions of years of evolution.
• Provides opportunities for research in genetics, medicine, biotechnology, and ecology.
• Loss of a species means permanent loss of unique biological information.
• Example: Study of extremophiles helps in developing new industrial enzymes and drugs.

Both values highlight the intangible yet crucial worth of preserving biodiversity.

A biodiversity hotspot is a biogeographic region that is both a significant reservoir of biodiversity and is threatened with destruction. The concept was introduced by Norman Myers (1988).

Criteria to qualify as a hotspot:

1. Endemism: The region must contain at least 1,500 species of endemic vascular plants (species found nowhere else on Earth).
2. Threat: The region must have lost at least 70% of its original natural vegetation (primary habitat).

Biodiversity Hotspots in India:

• The Western Ghats and Sri Lanka
• The Himalaya
• Indo-Burma region (includes North-East India)
• Sundaland (includes Nicobar Islands)

There are about 36 hotspots globally. India's four hotspots make it extremely rich in endemic species and conservation importance.

The major threats to biodiversity, often summarized as the 'Evil Quartet', include:

• Habitat Loss and Fragmentation: The most important cause. Deforestation, urbanization, and agriculture destroy natural habitats. Example: Loss of tropical rainforests.
• Over-exploitation: Excessive harvesting of resources beyond regeneration capacity. Example: Overfishing, hunting.
• Biological Invasions (Alien Species): Introduction of exotic species that outcompete native species. Example: Water hyacinth, Lantana.
• Co-extinctions: When a species becomes extinct, other species dependent on it also disappear. Example: Extinction of a host leads to extinction of its parasites.

Other threats:

• Poaching of wildlife for skin, ivory, horns.
• Human-wildlife conflicts.
• Pollution (air, water, soil).
• Climate change altering habitats and ranges.

Controlling these threats is essential for conserving global biodiversity.

Habitat loss is the destruction or degradation of the natural home of species, and is considered the single most important cause of loss of biodiversity.

Causes of Habitat Loss:

• Deforestation for agriculture, settlements, and industries.
• Mining and construction of dams.
• Urbanization and infrastructure development.
• Draining of wetlands and destruction of coral reefs.

Habitat Fragmentation:

• Large continuous habitats get divided into smaller, isolated patches (e.g., due to roads, railways).
• Effects include:
  • Reduced population size, leading to inbreeding.
  • Restricted movement and migration of animals.
  • Increased 'edge effects' that make patches vulnerable.
  • Disruption of breeding and feeding patterns.

Example: The Amazon rainforest and tropical forests are being cleared rapidly, threatening thousands of species. Mammals and birds requiring large territories are the worst affected.

Biological invasion refers to the introduction and spread of non-native (exotic/alien) species into an ecosystem where they are not naturally found. These species may be introduced accidentally or intentionally.

How invasive species threaten native biodiversity:

• Competition: They outcompete native species for food, space, and resources.
• Predation: They may prey on native species that have no defenses against them.
• Habitat Alteration: They can change the physical structure of habitats.
• Disease: They may introduce new pathogens.
• No Natural Enemies: They multiply rapidly due to absence of natural predators.

Examples in India:

• Water Hyacinth (Eichhornia) – 'Terror of Bengal', clogs water bodies.
• Lantana camara – invades forests and grasslands.
• Parthenium (Congress grass) – causes allergies and displaces crops.
• African catfish (Clarias gariepinus) – threatens native fish.

Invasive species are one of the leading causes of species extinction worldwide.

Human-wildlife conflict (HWC) refers to negative interactions between humans and wild animals leading to loss of life, property, or resources on both sides.

Causes:

• Habitat loss and fragmentation forcing animals into human areas.
• Expansion of agriculture and settlements into forest zones.
• Depletion of prey base and food scarcity.
• Blocking of traditional migration routes.

Consequences:

• Crop damage and livestock predation.
• Human injuries and deaths.
• Retaliatory killing of wild animals.
• Economic losses to communities.

Measures to Reduce Conflict:

• Construction of physical barriers (fences, trenches, walls).
• Creation of wildlife corridors for safe movement.
• Early warning systems and community awareness.
• Adequate compensation to affected people.
• Restoration of natural habitats and prey base.

Example: Elephant-human conflict in states like Kerala, Assam, and West Bengal.

Poaching is the illegal hunting, killing, or capturing of wild animals, usually for commercial gain from their body parts.

Reasons for Poaching:

• Ivory from elephant tusks.
• Skin and fur of tigers, leopards.
• Horns of rhinoceros (believed to have medicinal value).
• Musk from musk deer, bones, and organs for traditional medicine.
• Exotic pet trade and trophy hunting.

Impacts:

• Rapid decline and possible extinction of targeted species.
• Disruption of ecological balance and food chains.
• Loss of keystone and flagship species (e.g., tiger).
• Encourages organized illegal wildlife trade.

Control Measures:

• Strict enforcement of the Wildlife Protection Act, 1972.
• Anti-poaching squads and patrolling.
• International cooperation through CITES.
• Community involvement and awareness.

Example: Poaching of the one-horned rhino in Kaziranga National Park.

The IUCN (International Union for Conservation of Nature) classifies species based on their extinction risk in the Red Data Book. Major categories include:

• Extinct (EX): Species that no longer exist anywhere on Earth. Example: Dodo, Passenger pigeon.
• Extinct in the Wild (EW): Survive only in captivity or cultivation.
• Endangered (EN): Species facing very high risk of extinction in the near future. Example: Bengal Tiger, Great Indian Bustard.
• Vulnerable (VU): Species likely to become endangered if threats continue. Example: Blue whale, Snow leopard.
• Rare Species: Species with small populations that are not currently endangered but are at risk. Often localized or found in restricted areas.
• Threatened: Umbrella term covering endangered and vulnerable species.

The Red List helps prioritize conservation efforts and monitor the status of species worldwide.

EDGE stands for Evolutionarily Distinct and Globally Endangered species. It is a conservation concept developed by the Zoological Society of London (ZSL).

Meaning:

• Evolutionarily Distinct (ED): Species that have few close relatives and represent a unique branch of the tree of life. Their extinction would result in a disproportionate loss of evolutionary history.
• Globally Endangered (GE): Species that are at high risk of extinction.

Importance:

• EDGE species are unique and irreplaceable — if lost, there is nothing similar to replace them.
• They preserve unique genetic and evolutionary information.
• Helps prioritize species that are often neglected in mainstream conservation.

Examples of EDGE species:

• Gharial (India)
• Pygmy hippopotamus
• Chinese giant salamander
• Aye-aye (Madagascar)

The EDGE of Existence programme focuses conservation attention on these unique and threatened species.

Conservation strategies are broadly divided into two types:

In-situ examples: Jim Corbett National Park, Nilgiri Biosphere Reserve.

Ex-situ examples: National Bureau of Plant Genetic Resources (NBPGR), Cryopreservation of gametes, National Gene Bank.

Both approaches are complementary and essential for effective biodiversity conservation.

In-situ conservation means conserving biodiversity within natural habitats. Major protected areas in India include:

• National Parks:

  • Strictly reserved for wildlife protection.
  • No human activity, grazing, or cultivation allowed.
  • Example: Kaziranga, Jim Corbett, Gir National Park.

• Wildlife Sanctuaries:

  • Reserved for protection of wildlife.
  • Certain human activities like grazing may be permitted.
  • Example: Periyar, Bharatpur (Keoladeo) Sanctuary.

• Biosphere Reserves:

  • Large protected areas with core, buffer, and transition zones.
  • Conserve ecosystems along with cultural heritage.
  • Example: Nilgiri, Sundarbans, Nanda Devi.

• Sacred Groves:

  • Forest patches protected by local communities on religious grounds.
  • Example: Sacred groves in Meghalaya, Rajasthan, and Western Ghats.

• Conservation and Community Reserves.

These areas allow species to evolve naturally and maintain ecological balance.

Ex-situ conservation involves conserving components of biodiversity outside their natural habitats.

Methods:

• Botanical Gardens: Conserve plants and their genetic diversity. Example: Indian Botanical Garden, Howrah.
• Zoological Parks (Zoos): Conserve animals and support captive breeding.
• Gene Banks / Seed Banks: Preserve seeds and genetic material under controlled conditions.
• Cryopreservation: Storage of gametes, embryos, and tissues at very low temperatures ( in liquid nitrogen).
• Tissue Culture and DNA Banks.
• Captive Breeding Programmes: Breeding endangered species in captivity and later releasing them into the wild.

Advantages:

• Useful for critically endangered species.
• Enables captive breeding and reintroduction.
• Allows scientific research and genetic study.

Limitations:

• Expensive to maintain.
• Limited genetic diversity can be conserved.
• Species may lose natural adaptability.
• Animals may face difficulty adapting after release.

India is divided into 10 biogeographic zones based on climate, geography, flora, and fauna. These zones represent distinct ecological regions:

1. Trans-Himalayan Zone: Cold, arid region of Ladakh; home to snow leopard, wild yak.
2. Himalayan Zone: High mountains with alpine and temperate vegetation.
3. Indian Desert Zone: Thar desert of Rajasthan; adapted xerophytic species.
4. Semi-Arid Zone: Transitional between desert and forests.
5. Western Ghats: Biodiversity hotspot with high endemism.
6. Deccan Plateau: Largest zone; deciduous forests and scrublands.
7. Gangetic Plain: Fertile alluvial plains.
8. North-East India: Rich in rainforests and endemic species.
9. Islands: Andaman, Nicobar, and Lakshadweep with unique marine and island biodiversity.
10. Coasts: Long coastline with mangroves, estuaries, and coral reefs.

Significance:

• Helps in planning conservation strategies.
• Represents the vast ecological and species diversity of India.
• Aids in identifying priority areas for protection.

India is recognized as one of the 17 mega-diverse countries of the world, which together hold nearly 70% of the Earth's biodiversity.

Reasons / Justification:

• Rich Species Diversity: India harbors about 7-8% of all recorded species in the world while occupying only 2.4% of the world's land area.
• Number of Species: Over 45,000 species of plants and 91,000 species of animals have been recorded.
• High Endemism: A large proportion of species are endemic (found nowhere else), especially in the Western Ghats and North-East.
• Biodiversity Hotspots: India has four hotspots – Himalaya, Western Ghats, Indo-Burma, and Sundaland.
• Varied Climatic and Geographic Zones: From the Himalayas to coastal regions, deserts to rainforests.
• Centre of Origin: India is a centre of origin for many cultivated plants and domesticated animals (e.g., rice, sugarcane, mango).
• Cultural Diversity: Rich traditional knowledge and ethnobiological practices.

These facts firmly establish India as a mega-diversity nation.

Biodiversity holds immense value for human beings and the planet. These values can be classified as follows:

1. Ecological / Environmental Value:

• Maintains ecological balance through food chains and food webs.
• Provides ecosystem services: oxygen production, carbon fixation, climate regulation, soil fertility, water purification, and pollination.

2. Economic Value:

• Consumptive Use Value: Directly consumed resources – food, fuelwood, fodder.
• Productive Use Value: Commercially traded goods – timber, medicines, silk, fibre.
• Supports agriculture, industry, fisheries, and pharmaceuticals.

3. Social Value:

• Linked with cultural, religious, and traditional practices of communities.
• Sacred plants and animals form part of heritage.

4. Ethical / Moral Value:

• Every species has a right to exist; humans have a duty to protect them.

5. Aesthetic Value:

• Natural beauty promotes ecotourism, recreation, and mental well-being.

6. Informational / Scientific Value:

• Reservoir of genetic and scientific knowledge for research and biotechnology.

Importance for Sustainable Development:

• Provides continuous supply of natural resources for present and future generations.
• Maintains life-supporting ecological processes.
• Ensures food, health, and economic security.
• Enhances resilience against climate change.

Hence, conserving biodiversity is not just an environmental necessity but a foundation for long-term sustainable development.