Unit 3: Biodiversity and conservation - Subjective Questions

Biodiversity (biological diversity) refers to the variety and variability of life on Earth, encompassing all living organisms, the genes they contain, and the ecosystems they form. The term was coined by Walter G. Rosen (1985) and popularized by E.O. Wilson.

Three Levels of Biological Diversity:

• Genetic Diversity: Refers to the variation of genes within a species. It includes differences in DNA among individuals and populations.

  • Example: Different varieties of rice (over 50,000 varieties in India), or genetic variation among human populations.

• Species Diversity: Refers to the variety of species within a region. It includes species richness (number of species) and species evenness (relative abundance).

  • Example: The Western Ghats have a higher species diversity than a desert region.

• Ecosystem Diversity: Refers to the variety of ecosystems, habitats, and ecological processes in a given area.

  • Example: Forests, wetlands, grasslands, deserts, and coral reefs represent different ecosystems.

Together, these levels ensure the stability, productivity, and resilience of the biosphere.

Genetic Diversity refers to the total number of genetic characteristics (variety of genes) within a species. It arises from mutations, gene flow, sexual reproduction, and recombination.

Significance of Genetic Diversity:

• Adaptation: Enables species to adapt to changing environmental conditions such as climate change and disease.
• Survival & Evolution: Provides raw material for natural selection and evolution.
• Disease Resistance: Populations with higher genetic variation are more resistant to epidemics.
• Crop Improvement: Wild relatives of crops provide genes for developing high-yielding, pest-resistant varieties.
• Reduces Extinction Risk: Low genetic diversity leads to inbreeding depression and higher extinction risk.

Example: The genetic diversity in wild rice was used to develop disease-resistant cultivated rice varieties. India has rich genetic diversity in crops like rice, mango, and banana.

Conservation Importance: Preserving gene pools through seed banks, gene banks, and protected populations ensures future food security and ecological stability.

Species Diversity is determined by two components: species richness and species evenness.

Species Richness:

• Refers to the total number of different species present in a given area or community.
• It is a count-based measure.
• Example: A forest with 100 species has greater richness than one with 50 species.

Species Evenness (Equitability):

• Refers to the relative abundance or distribution of individuals among the different species.
• Measures how equally the species are represented.
• Example: If one species dominates while others are rare, evenness is low.

Comparison Table:

Collective Contribution: High diversity occurs when there is both high richness and high evenness. A community with many species that are evenly distributed is considered the most diverse and stable.

Biodiversity holds multiple values that justify its conservation:

1. Ecological Value:

• Maintains ecological balance through nutrient cycling, pollination, and climate regulation.
• Example: Forests regulate CO levels and prevent soil erosion.

2. Economic Value:

• Provides food, timber, medicines, fibers, and raw materials.
• Example: Nearly 25% of medicines are derived from plants; agriculture depends on biodiversity.

3. Social Value:

• Linked to social life, customs, religion, and traditions of communities.
• Example: Sacred groves, worship of plants (Tulsi, Peepal) and animals.

4. Aesthetic Value:

• The beauty of nature provides recreation, tourism, and inspiration.
• Example: Ecotourism, national parks, and wildlife photography.

5. Informational Value:

• Biodiversity is a source of scientific knowledge and genetic information.
• Example: Study of species for biotechnology and research.

6. Ethical/Existence Value:

• Every species has a right to exist irrespective of its use to humans.

These values highlight the multi-dimensional importance of biodiversity to human survival and well-being.

Ecosystem Services are the benefits that humans obtain from ecosystems, essential for survival and well-being. The Millennium Ecosystem Assessment (2005) classified them into four categories:

1. Provisioning Services:

• Products directly obtained from ecosystems.
• Examples: Food, fresh water, timber, fuel, fiber, medicinal plants.

2. Regulating Services:

• Benefits from the regulation of ecosystem processes.
• Examples: Climate regulation, water purification, flood control, pollination, disease control.

3. Cultural Services:

• Non-material benefits enriching quality of life.
• Examples: Recreation, ecotourism, spiritual and aesthetic values, education.

4. Supporting Services:

• Services necessary for production of all other services.
• Examples: Soil formation, nutrient cycling, photosynthesis, primary production.

Significance: These services are estimated to be worth trillions of dollars annually. Their degradation directly threatens human survival, making biodiversity conservation vital for sustaining ecosystem services.

Biodiversity Hotspots are biogeographic regions with exceptionally high levels of species richness and endemism that are under severe threat of destruction. The concept was introduced by Norman Myers (1988).

Criteria for a Biodiversity Hotspot:

• Species Endemism: The region must contain at least 1,500 species of endemic vascular plants (i.e., >0.5% of the world's total).
• Threat Level: The region must have lost at least 70% of its original natural vegetation (primary habitat).

Global Status: There are around 36 biodiversity hotspots worldwide.

Biodiversity Hotspots in India (4):

• The Western Ghats and Sri Lanka: Rich in endemic amphibians and plants.
• The Himalayas: Home to species like the red panda and snow leopard.
• Indo-Burma Region: Includes northeastern India, rich in flora and fauna.
• Sundaland (Nicobar Islands): Rich marine and terrestrial biodiversity.

Importance: Hotspots are conservation priorities because protecting them safeguards a large fraction of global biodiversity in relatively small areas.

Biodiversity faces numerous threats, primarily due to human activities. The major threats (often called the 'Evil Quartet') include:

1. Habitat Loss and Fragmentation:

• The most significant cause of biodiversity loss.
• Deforestation, urbanization, and agriculture destroy natural habitats.
• Example: Destruction of tropical rainforests.

2. Over-exploitation / Poaching:

• Excessive hunting, fishing, and harvesting of resources.
• Example: Poaching of tigers, rhinos, and elephants for skin, horn, and ivory.

3. Biological Invasions (Invasive Alien Species):

• Introduction of non-native species that outcompete native species.
• Example: Water hyacinth, Lantana camara, and Nile perch.

4. Co-extinctions:

• Extinction of one species leads to extinction of associated species.
• Example: Extinction of a host results in loss of its parasites.

Other Threats:

• Pollution (air, water, soil, pesticides)
• Climate change and global warming
• Human-wildlife conflicts
• Habitat degradation

Addressing these threats requires legal protection, habitat restoration, and sustainable practices.

Habitat Loss is the destruction or alteration of natural habitats making them unsuitable for the organisms that previously lived there. It is considered the most important cause of biodiversity loss and species extinction.

Causes of Habitat Loss:

• Deforestation for agriculture and timber
• Urbanization and industrialization
• Mining activities
• Construction of dams and infrastructure
• Conversion of wetlands into farmland

Habitat Fragmentation:

• When large, continuous habitats are broken into smaller, isolated patches.
• Occurs due to roads, railways, agriculture, and settlements.

Consequences of Fragmentation:

• Edge Effects: Altered conditions at habitat boundaries harm interior species.
• Reduced Population Size: Smaller patches support fewer individuals.
• Isolation: Restricted movement and gene flow between populations.
• Increased Extinction Risk: Species requiring large territories (e.g., tigers, elephants) are severely affected.

Example: The Amazon rainforest and tropical forests are losing area rapidly. In India, fragmentation threatens large mammals requiring extensive ranges.

Solution: Establishing wildlife corridors, protected areas, and reforestation programs.

Biological Invasions refer to the introduction and spread of invasive alien species (IAS) — non-native organisms that establish, proliferate, and cause harm to the native ecosystem.

How Invasive Species Threaten Biodiversity:

• Competition: They compete with native species for food, space, and resources, often outcompeting them.
• Predation: They may prey on native species that have no natural defenses.
• Habitat Alteration: They change the physical and chemical nature of habitats.
• Disease Introduction: They may introduce new pathogens.
• No Natural Predators: In new habitats, they lack natural enemies, leading to uncontrolled growth.

Examples of Invasive Species:

• Water Hyacinth (Eichhornia crassipes): 'Terror of Bengal,' clogs water bodies.
• Lantana camara: Aggressive weed affecting forests.
• Parthenium (Congress grass): Causes allergies and displaces native plants.
• Nile Perch: Introduced in Lake Victoria, caused extinction of many cichlid fishes.
• African Catfish (Clarias gariepinus): Threatens native Indian catfishes.

Control Measures: Quarantine regulations, biological control, mechanical removal, and public awareness are essential to manage invasions.

Human-Wildlife Conflict (HWC) refers to negative interactions between humans and wild animals, resulting in harm to people, animals, or resources.

Causes:

• Habitat loss and fragmentation forcing animals into human areas
• Encroachment into forest areas and wildlife corridors
• Depletion of prey and food resources in the wild
• Population growth and expanding agriculture
• Crop-raiding by herbivores

Consequences:

• Loss of human life and injuries (e.g., elephant, tiger, leopard attacks)
• Crop damage and livestock predation causing economic loss
• Retaliatory killing of wildlife by affected communities
• Damage to property

Examples:

• Elephants raiding crops in Assam, Kerala, and West Bengal
• Leopard attacks in urban fringes
• Man-eater tigers in the Sundarbans

Mitigation Measures:

• Construction of barriers (trenches, solar fences)
• Wildlife corridors to allow safe animal movement
• Compensation schemes for affected farmers
• Early warning systems and awareness programs
• Habitat improvement to maintain prey base

Effective management balances conservation goals with community welfare.

The IUCN (International Union for Conservation of Nature) Red List classifies species based on their risk of extinction. The major categories are:

1. Extinct (EX):

• No living individuals remain.
• Example: Dodo, Passenger pigeon.

2. Extinct in the Wild (EW):

• Survives only in captivity or cultivation.

3. Critically Endangered (CR):

• Extremely high risk of extinction in the wild.
• Example: Gharial, Great Indian Bustard.

4. Endangered (EN):

• Very high risk of extinction.
• Example: Asiatic lion, Bengal tiger.

5. Vulnerable (VU):

• High risk of endangerment in the wild.
• Example: Sloth bear, Blue whale.

6. Near Threatened (NT):

• Likely to become threatened in the near future.

7. Least Concern (LC):

• Widespread and abundant species.

8. Data Deficient (DD):

• Inadequate information to assess risk.

9. Not Evaluated (NE):

• Not yet assessed against the criteria.

This classification helps prioritize conservation efforts for species most at risk of extinction.

These are categories of species facing varying degrees of extinction risk:

Endangered Species:

• Species in immediate danger of extinction if the factors causing decline continue.
• Their numbers have been reduced to a critical level.
• Examples: Bengal tiger, Asiatic lion, Snow leopard, Great Indian Bustard.

Vulnerable Species:

• Species whose population is declining and likely to move into the endangered category in the near future.
• Not in immediate danger but at high risk.
• Examples: Sloth bear, Blue whale, Gaur.

Rare Species:

• Species with small populations that are not endangered or vulnerable but are at risk.
• Localized within restricted geographical areas or thinly scattered.
• Examples: Hornbill, certain orchids.

Comparison Table:

Each category requires targeted conservation strategies based on the degree of threat.

EDGE stands for Evolutionarily Distinct and Globally Endangered species. The EDGE of Existence programme was launched by the Zoological Society of London (ZSL) in 2007.

Concept:

• Evolutionarily Distinct (ED): Species that have few close relatives and represent a unique branch on the tree of life. They are often the last survivors of ancient lineages.
• Globally Endangered (GE): Species that are at high risk of extinction according to the IUCN Red List.

EDGE species combine both these criteria — they are unique AND threatened.

Importance in Conservation:

• Irreplaceable Genetic Heritage: Their extinction means loss of unique evolutionary history that cannot be recovered.
• Conservation Prioritization: Helps focus limited resources on species representing disproportionate evolutionary diversity.
• Unique Biology: These species often have distinctive characteristics and ecological roles.

Examples of EDGE Species:

• Gharial (India) — unique crocodilian
• Pygmy Hippopotamus
• Chinese Giant Salamander
• Aye-aye (Madagascar)
• Purple Frog (Western Ghats, India)

By protecting EDGE species, we preserve millions of years of unique evolutionary history.

In-situ Conservation means the conservation of species in their natural habitats or ecosystems. It aims to protect entire ecosystems along with all their biological components.

Advantages:

• Species evolve naturally in their own environment
• Entire ecosystems and food chains are conserved
• Cost-effective and self-sustaining
• Maintains natural ecological interactions

Methods / Protected Areas in India:

1. Biosphere Reserves:

• Large protected areas conserving ecosystems and genetic resources.
• Have core, buffer, and transition zones.
• Example: Nilgiri, Nanda Devi, Sundarbans. (India has 18 biosphere reserves)

2. National Parks:

• Strictly protected areas; no human activity or grazing allowed.
• Example: Jim Corbett, Kaziranga, Gir National Park.

3. Wildlife Sanctuaries:

• Protected areas for wildlife; limited human activities permitted.
• Example: Bharatpur Bird Sanctuary, Periyar.

4. Sacred Groves:

• Forest patches protected by local communities for religious reasons.
• Example: Groves in Rajasthan, Meghalaya, Western Ghats.

5. Conservation Reserves & Community Reserves.

In-situ conservation is the most effective way to protect biodiversity in its natural, dynamic context.

Ex-situ Conservation means the conservation of species outside their natural habitats in artificially controlled conditions. It is used for species that are on the verge of extinction or require special protection.

Methods of Ex-situ Conservation:

1. Zoological Parks (Zoos):

• Animals are kept, bred, and protected in captivity.
• Example: National Zoological Park, Delhi.

2. Botanical Gardens:

• Living collections of plants for conservation, research, and education.
• Example: Indian Botanical Garden, Kolkata.

3. Gene Banks / Seed Banks:

• Preservation of seeds, pollen, and genetic material.
• Example: National Bureau of Plant Genetic Resources (NBPGR), New Delhi.

4. Cryopreservation:

• Storage of gametes, embryos, and tissues at very low temperatures ( in liquid nitrogen).

5. Tissue Culture:

• In-vitro propagation of plants from cells and tissues.

6. Captive Breeding Programs:

• Breeding endangered species in captivity for later release.
• Example: Gharial breeding, Project Tiger captive programs.

Advantages:

• Endangered species can be bred and multiplied
• Genetic material can be preserved long-term

Limitations:

• Expensive; limited number of individuals; loss of natural behavior.

Ex-situ methods complement in-situ conservation for comprehensive biodiversity protection.

Both are complementary approaches to biodiversity conservation but differ in methodology and application.

In-situ Conservation:

• Conservation of species in their natural habitat.
• Protects entire ecosystems.
• Examples: National parks, sanctuaries, biosphere reserves.

Ex-situ Conservation:

• Conservation of species outside their natural habitat in controlled conditions.
• Focuses on individual species.
• Examples: Zoos, botanical gardens, gene banks.

Comparison Table:

Conclusion: In-situ conservation is preferred as it allows natural ecological processes, while ex-situ conservation acts as a backup for critically endangered species and preserves genetic material. A combination of both ensures effective biodiversity conservation.

India is divided into 10 biogeographic zones based on climate, geography, vegetation, and fauna. This classification was developed by Rodgers and Panwar (1988).

The 10 Biogeographic Zones of India:

• 1. Trans-Himalayan Zone: Cold desert region of Ladakh; sparse vegetation (wild sheep, goats).
• 2. Himalayan Zone: High mountains with rich alpine flora and fauna (snow leopard, red panda).
• 3. Indian Desert Zone: Thar desert of Rajasthan; xerophytic vegetation (camel, desert fox).
• 4. Semi-Arid Zone: Transition between desert and forests (Gujarat, Rajasthan; Asiatic lion).
• 5. Western Ghats: Rich in endemic species; one of the world's biodiversity hotspots.
• 6. Deccan Plateau: Largest zone; deciduous forests (tiger, deer, elephant).
• 7. Gangetic Plains: Fertile alluvial plains; agricultural biodiversity.
• 8. North-East India: Rainforests, extremely rich biodiversity and endemism.
• 9. Islands: Andaman, Nicobar, and Lakshadweep; unique marine and endemic species.
• 10. Coastal Zone: Coastlines, mangroves, coral reefs, and estuaries.

Contribution to Biodiversity:

• Diverse climatic and geographic conditions support varied ecosystems.
• High endemism due to isolated regions.
• Wide range of habitats from deserts to rainforests.

This diversity of zones makes India one of the most biologically rich countries in the world.

India is recognized as one of the 17 mega-diverse countries of the world, which together account for nearly 60-70% of global biodiversity.

Reasons Why India is a Mega-Diversity Nation:

1. Species Richness:

• India has about 8% of the world's recorded species while occupying only 2.4% of the world's land area.
• Over 91,000 species of animals and 45,000 species of plants are recorded.

2. Endemism:

• High level of endemic species (found nowhere else).
• About 33% of flowering plants are endemic to India.

3. Biodiversity Hotspots:

• India hosts 4 biodiversity hotspots: Himalayas, Western Ghats, Indo-Burma, and Sundaland (Nicobar Islands).

4. Diverse Ecosystems:

• Ranges from deserts, forests, wetlands, grasslands to coral reefs and mangroves.

5. Agricultural Diversity:

• Center of origin for many crops (rice, sugarcane, mango, banana).
• Rich in genetic diversity of domesticated plants and animals.

6. Cultural Diversity:

• Long tradition of conservation through sacred groves and religious practices.

Conclusion: The combination of varied climate, topography, and evolutionary history has made India exceptionally rich in biodiversity, thereby earning its status as a mega-diversity nation.

Ecosystem Diversity refers to the variety of ecosystems, habitats, biological communities, and ecological processes within a particular region or on Earth. It represents the diversity at the level of communities and ecosystems.

Components of Ecosystem Diversity:

• Habitat Diversity: Different types of habitats (forests, deserts, wetlands, oceans).
• Community Diversity: Variety of biological communities.
• Ecological Processes: Nutrient cycling, energy flow, food webs, and succession.

Examples of Different Ecosystems:

• Terrestrial: Forests, grasslands, deserts, tundra
• Aquatic: Rivers, lakes, oceans, wetlands, coral reefs

Why It Is the Highest Level:

• Encompasses Other Levels: It includes genetic and species diversity within its scope.
• Broadest Scale: Operates at the largest scale of biological organization.
• Interactions: Involves interactions between living organisms and their non-living environment.
• Maintains Balance: Different ecosystems perform vital functions that maintain the biosphere.

Significance:

• Provides varied ecosystem services
• Supports overall ecological stability
• Loss of ecosystem diversity affects all lower levels of biodiversity

Thus, ecosystem diversity forms the foundation for maintaining genetic and species diversity, making it the most comprehensive level.

Biodiversity is crucial for the survival of humans and the sustainability of life on Earth. Its importance can be understood through the following points:

1. Ecological Stability:

• Diverse ecosystems are more stable and resilient to disturbances.
• Maintains balance in nature through food chains and food webs.

2. Provision of Resources:

• Food: Crops, livestock, fish, and fruits.
• Medicine: About 25% of modern medicines are derived from plants.
• Raw Materials: Timber, fibers, resins, and industrial products.

3. Ecosystem Services:

• Regulating: Climate regulation, water purification, flood control.
• Supporting: Soil formation, nutrient cycling, pollination.
• Provisioning: Direct supply of goods.

4. Environmental Benefits:

• Oxygen production and carbon dioxide absorption.
• Prevention of soil erosion and maintenance of soil fertility.
• Regulation of the water cycle.

5. Economic Importance:

• Supports agriculture, fisheries, forestry, and tourism industries.
• Genetic resources for crop and livestock improvement.

6. Scientific and Educational Value:

• Source of research and knowledge in biotechnology and medicine.

7. Cultural and Aesthetic Value:

• Recreation, spiritual well-being, and cultural identity.

Conclusion: Biodiversity is the foundation of ecosystem services and human well-being. Its conservation is essential for a sustainable future, food security, and the balance of the biosphere.