Unit 3: Biodiversity and conservation - Subjective Questions

Biodiversity is the variety and variability of living organisms and the ecological complexes in which they occur. It includes diversity within species, between species, and among ecosystems.

The three major levels are:

• Genetic diversity: Variation in genes within a species. For example, different varieties of rice, wheat, and mango possess different genetic characteristics. It enables species to adapt to environmental changes and resist diseases.
• Species diversity: Variety and relative abundance of species in a particular region. Tropical rainforests and coral reefs are examples of ecosystems with high species diversity.
• Ecosystem diversity: Variety of habitats, biological communities, and ecological processes in a region. Forests, grasslands, deserts, wetlands, and marine ecosystems represent different forms of ecosystem diversity.

All three levels are interconnected and are essential for ecological stability and long-term survival of life.

The three levels of biodiversity can be distinguished as follows:

Genetic diversity occurs within a species, species diversity occurs among species, and ecosystem diversity occurs among habitats and ecological systems.

Biodiversity supports human well-being through the following ecosystem services:

• Provisioning services: Supply of food, freshwater, fuelwood, timber, fibers, medicines, and genetic resources.
• Regulating services: Regulation of climate, floods, pests, diseases, water quality, and soil erosion. Pollination and carbon sequestration are important examples.
• Supporting services: Nutrient cycling, soil formation, decomposition, photosynthesis, and maintenance of food chains.
• Cultural services: Recreation, tourism, spiritual enrichment, education, and aesthetic enjoyment.

For example, forests store carbon and regulate rainfall, wetlands purify water and reduce floods, and insects pollinate crops. Thus, biodiversity forms the natural foundation of economies, public health, food security, and environmental stability.

Biodiversity has several interrelated values:

• Ecological value: Species maintain food webs, nutrient cycles, soil fertility, pollination, decomposition, and ecosystem stability.
• Economic value: Biodiversity provides food, timber, fibers, medicines, fuels, industrial materials, and income through agriculture, fisheries, forestry, and tourism.
• Social value: Many communities associate plants, animals, forests, and rivers with customs, religion, livelihoods, and traditional knowledge.
• Aesthetic value: Natural landscapes and wildlife provide beauty, inspiration, recreation, and mental well-being. They also support ecotourism.
• Informational value: Genes, species, and ecosystems contain information useful for scientific research, biotechnology, medicine, agriculture, and understanding evolution.

Conserving biodiversity therefore protects ecological processes as well as present and future human interests.

A biodiversity hotspot is a biogeographic region containing exceptional concentrations of endemic species that is also experiencing severe habitat loss.

To qualify as a hotspot, a region must:

• Contain at least 1,500 endemic vascular plant species.
• Have lost at least 70% of its original natural vegetation.

Hotspots are significant because:

• They contain large numbers of unique species within relatively small areas.
• Many hotspot species occur nowhere else and may become extinct if their habitats disappear.
• Conservation investment in these regions can protect a high proportion of global biodiversity.
• They help governments and organizations prioritize limited conservation resources.

However, hotspot conservation should complement, rather than replace, protection of other ecologically important regions.

India is associated with four global biodiversity hotspots:

• Himalaya: Includes the Indian Himalayan region and contains rich altitudinal variation, endemic plants, pheasants, red panda, and snow leopard.
• Indo-Burma: Covers much of northeastern India and the Andaman Islands. It has diverse forests, freshwater fauna, reptiles, birds, and orchids.
• Western Ghats and Sri Lanka: The Western Ghats possess high endemism among flowering plants, amphibians, reptiles, and freshwater fishes. Important species include the lion-tailed macaque and Nilgiri tahr.
• Sundaland: In India, this hotspot is represented by the Nicobar Islands. It contains tropical forests, coastal ecosystems, and many island-specific species.

These regions are priorities for conservation because they combine high endemism with extensive habitat degradation and other human pressures.

Habitat loss occurs when a natural habitat is destroyed or converted so that it can no longer support its original biological community. Habitat fragmentation divides a continuous habitat into smaller, isolated patches.

Major causes include:

• Expansion of agriculture and settlements
• Deforestation and logging
• Mining, dams, roads, and industries
• Urbanization and infrastructure development
• Wetland drainage and coastal development

Their effects include:

• Reduction in food, shelter, and breeding sites
• Isolation of wildlife populations and reduced gene flow
• Increased inbreeding and local extinction risk
• Greater exposure to invasive species and human disturbance
• Creation of edge effects that alter temperature, light, and humidity

Protection of critical habitats, restoration of degraded areas, and creation of wildlife corridors can reduce these impacts.

Poaching is the illegal hunting, capturing, or killing of wild organisms. Wildlife is poached for meat, skins, horns, tusks, bones, pets, medicines, ornaments, and commercial trade.

Its major impacts are:

• Rapid decline of targeted species
• Disturbance of food chains and ecological relationships
• Loss of genetic diversity in small populations
• Local or global extinction of threatened species
• Growth of organized illegal wildlife trade

Control measures include:

• Strict enforcement of wildlife protection laws
• Effective patrolling and intelligence networks
• Monitoring trade routes and online markets
• Use of forensic science and digital surveillance
• Reduction of consumer demand through awareness
• International cooperation under agreements such as CITES
• Participation of local communities in conservation and alternative livelihoods

Successful control requires both law enforcement and removal of the economic incentives behind poaching.

A biological invasion occurs when a non-native species is introduced, establishes a self-sustaining population, spreads, and causes ecological or economic harm.

Common pathways include:

• International trade and transport
• Horticulture, aquaculture, and the pet trade
• Accidental movement in cargo, ballast water, or packaging
• Deliberate introduction for food, forestry, or pest control

Major impacts include competition with native species, predation, disease transmission, habitat alteration, and economic losses. Examples in India include water hyacinth, Lantana camara, and Parthenium hysterophorus.

Management involves:

• Preventing introductions through quarantine and risk assessment
• Early detection and rapid eradication
• Mechanical, chemical, or biological control
• Long-term monitoring and habitat restoration
• Public awareness to prevent intentional release

Prevention is generally less expensive and more effective than controlling an established invasive species.

Human-wildlife conflict refers to interactions in which the activities of people and wild animals negatively affect one another.

Major causes are:

• Habitat loss and fragmentation
• Encroachment into forests and wildlife corridors
• Decline of natural prey and water sources
• Cultivation of attractive crops near protected areas
• Improper waste disposal that attracts wildlife
• Roads, railways, and other infrastructure in animal habitats

Consequences include crop damage, livestock loss, human injury or death, retaliatory killing of animals, economic hardship, and reduced public support for conservation.

Mitigation measures include protecting corridors, restoring habitats, using barriers and early-warning systems, improving livestock enclosures, rapidly compensating affected people, modifying crops near conflict zones, managing waste, and involving communities in planning. Mitigation should promote coexistence instead of relying only on capture or killing of animals.

These terms describe different conditions of species conservation concern:

• Extinct species: A species for which there is no reasonable doubt that the last individual has died. It no longer exists anywhere on Earth.
• Endangered species: A species facing a very high risk of extinction in the wild because of severe population decline, restricted distribution, or major threats.
• Vulnerable species: A species facing a high risk of extinction in the wild, but generally at a lower immediate risk than an endangered species.
• Rare species: A species with a small population or restricted distribution. It may not currently satisfy formal threatened-category criteria but can be highly susceptible to environmental changes.

The categories should not be treated as fixed labels. A species may move into a higher or lower risk category as its population, habitat, threats, and available scientific evidence change.

EDGE stands for Evolutionarily Distinct and Globally Endangered. EDGE species are threatened species that represent an unusually large amount of unique evolutionary history.

• Evolutionary distinctiveness: A species is evolutionarily distinct when it has few close living relatives and occupies a long, isolated branch of the evolutionary tree. Its extinction would eliminate unique genetic traits and evolutionary history.
• Global endangerment: This represents the species' risk of extinction, commonly determined using recognized conservation assessments such as the IUCN Red List.

EDGE conservation is important because conventional programs may overlook unusual species with no strong cultural or economic appeal. Protecting them preserves unique ecological functions, adaptations, and biological information. Examples associated with India include highly distinctive threatened mammals, reptiles, amphibians, and birds such as the gharial and Bengal florican.

The two approaches are complementary. In-situ conservation should normally be the primary strategy, while ex-situ conservation can support recovery, research, and reintroduction when wild populations are severely threatened.

In-situ conservation protects biodiversity within its natural environment. Major methods include:

• National parks: Highly protected areas established to conserve entire ecosystems and wildlife, with strict restrictions on resource use.
• Wildlife sanctuaries: Areas where wildlife and habitats are protected, although certain regulated human activities may be permitted.
• Biosphere reserves: Large areas combining conservation, research, sustainable resource use, and community participation through core, buffer, and transition zones.
• Conservation and community reserves: Protected areas that encourage participation by local communities and private landholders.
• Sacred groves: Forest patches protected by communities because of religious or cultural traditions.
• Wildlife corridors: Habitat links that allow movement, dispersal, migration, and gene flow between populations.

These methods conserve species together with their habitats, ecological interactions, and evolutionary processes.

Ex-situ conservation protects species or their genetic material outside natural habitats. Major methods are:

• Zoos and aquaria: Maintain and breed threatened animals under managed conditions.
• Botanical gardens and arboreta: Preserve living collections of rare and threatened plants.
• Seed banks: Store viable seeds under controlled temperature and humidity.
• Gene banks: Preserve pollen, tissues, DNA, sperm, ova, or embryos.
• Tissue culture and cryopreservation: Propagate plants and preserve biological material at very low temperatures.
• Captive breeding: Increases the population of threatened animals for possible reintroduction.

Ex-situ methods prevent immediate extinction, support research, and provide material for population reinforcement. However, they can be expensive and may cause inbreeding, domestication, or loss of survival skills. Reintroduction succeeds only when the original threats have been controlled and suitable habitat remains available.

India is commonly divided into ten biogeographic zones based on climate, relief, vegetation, and fauna:

1. Trans-Himalaya: Cold, arid high-altitude region with sparse vegetation and species such as the snow leopard and wild yak.
2. Himalaya: Mountain forests and alpine habitats with strong altitudinal variation.
3. Indian Desert: Arid ecosystems of the Thar and Kachchh, supporting drought-adapted organisms.
4. Semi-Arid: Grasslands, scrublands, and dry forests between desert and more humid regions.
5. Western Ghats: Tropical forests with exceptionally high richness and endemism.
6. Deccan Peninsula: India's largest zone, dominated by plateaus, deciduous forests, and thorn forests.
7. Gangetic Plain: Fertile alluvial plains extensively modified by agriculture and settlements.
8. Coasts: Beaches, estuaries, lagoons, mangroves, and coastal wetlands.
9. Northeast India: High-rainfall forests with rich Indo-Malayan biodiversity.
10. Islands: Andaman, Nicobar, and Lakshadweep ecosystems with coral reefs and many endemic species.

India is regarded as a mega-diversity nation because it supports exceptionally high species richness, ecosystem variety, and endemism within a relatively small share of the world's land area.

Important reasons include:

• Great variation in altitude, rainfall, temperature, soils, and topography
• Ecosystems ranging from alpine meadows and tropical forests to deserts, wetlands, mangroves, islands, and coral reefs
• Ten major biogeographic zones
• Parts of four global biodiversity hotspots
• High endemism in regions such as the Western Ghats, Himalaya, Northeast, and islands
• Rich agricultural biodiversity, including traditional crop varieties and livestock breeds
• Location at the meeting point of major biogeographic realms

India's cultural traditions and community conservation practices also contribute to biodiversity protection. However, habitat degradation, overexploitation, invasive species, pollution, and climate change place this natural wealth under considerable pressure.

Biodiversity strengthens ecosystem functioning in several ways:

• Functional complementarity: Different species use resources in different ways, improving overall resource utilization and productivity.
• Response diversity: Species respond differently to drought, disease, fire, and other disturbances, reducing the chance that all ecological functions fail simultaneously.
• Food-web stability: Diverse food webs provide alternative feeding relationships when one population declines.
• Nutrient cycling: Plants, animals, fungi, and microorganisms collectively support decomposition, soil formation, and nutrient recycling.
• Genetic adaptability: Genetic variation allows populations to adapt to changing environmental conditions.
• Ecosystem recovery: Diverse communities often recover more effectively after disturbances.

Although the contribution of each species differs, losing species can weaken ecological interactions and reduce resilience, especially when keystone species, pollinators, decomposers, or ecosystem engineers are affected.

Threats to biodiversity rarely operate independently. Habitat fragmentation can isolate small populations, making them more vulnerable to inbreeding, poaching, invasive species, disease, and climate change. Roads entering forests may fragment habitats while also increasing human access, illegal hunting, and wildlife collisions. Resource scarcity can force animals into farms and settlements, intensifying human-wildlife conflict and retaliatory killing.

An integrated strategy should include:

• Protection and restoration of critical habitats
• Wildlife corridors to maintain movement and gene flow
• Strong enforcement against poaching and illegal trade
• Prevention, early detection, and control of invasive species
• Scientific monitoring of populations and threats
• Conflict mitigation with timely compensation and early-warning systems
• Sustainable livelihoods and community participation
• Ex-situ breeding or genetic storage for species at immediate risk
• Environmental assessment of infrastructure projects
• Coordination among governments, scientists, communities, and conservation organizations

Such a strategy addresses both direct biological threats and their underlying social and economic causes.

A combined recovery programme may proceed through the following stages:

• Assessment: Study population size, genetic diversity, habitat requirements, distribution, and causes of decline.
• Habitat protection: Protect breeding and feeding sites, restore degraded habitat, and establish corridors. This is the in-situ foundation of recovery.
• Threat control: Reduce poaching, invasive species, pollution, disease, and human-wildlife conflict.
• Managed population: Establish captive breeding, botanical propagation, seed banking, or cryopreservation when the wild population is dangerously small.
• Genetic management: Select breeding individuals carefully to minimize inbreeding and retain genetic diversity.
• Reintroduction: Release suitable individuals into secure habitats after health checks, acclimatization, and removal of original threats.
• Monitoring: Track survival, reproduction, movement, and ecological impact after release.
• Community involvement: Engage local people through awareness, employment, compensation, and shared conservation benefits.

The programme succeeds when a self-sustaining wild population is restored, rather than merely maintaining individuals in captivity.