1. Levels of Biodiversity

Biodiversity (General Issues)

Biodiversity, a portmantead of “biological diversity,” refers to the variety of life on Earth at all its levels, from genes to ecosystems, and the ecological and evolutionary processes that sustain it. It’s the very foundation of life and sustainable development, providing essential goods and services that underpin human well-being.

1. Levels of Biodiversity

Biodiversity is typically understood at three main hierarchical levels:

• 1.1. Genetic Diversity
• Definition: The variation of genes within a species. It encompasses the differences in DNA sequences among individuals of the same species.
• Importance:
• Allows species to adapt to changing environmental conditions (e.g., climate change, new diseases).
• Higher genetic diversity within a population reduces the risk of inbreeding depression.
• Provides raw material for natural selection.
• Examples: Different varieties of rice (Basmati, Sona Masuri), varying resistance to pests in a crop, different coat colours in tigers.
• Impact of Loss: Reduced ability of a species to cope with environmental stressors, making it more vulnerable to extinction. Monoculture (cultivating a single crop type) significantly reduces genetic diversity.

• 1.2. Species Diversity
• Definition: The variety of different species present in a particular region or ecosystem. It includes both the number of species (species richness) and their relative abundance (species evenness).
• Key Terms:
• Species Richness: The total number of different species in a given area.
• Species Evenness: The relative abundance of each species in an area. An ecosystem where all species have similar population sizes has high evenness.
• Importance:
• A more diverse ecosystem is generally more productive and stable.
• Provides various ecosystem services (pollination, pest control).
• Aesthetical and cultural value.
• Examples: A rainforest with thousands of tree species vs. a pine forest with only a few.
• Impact of Loss: Extinction of species leads to the loss of unique genetic material, disruption of food webs, and reduced ecosystem resilience.

• 1.3. Ecosystem Diversity
• Definition: The variety of habitats, biotic communities, and ecological processes in the biosphere. It refers to the diversity of different ecosystems across the globe.
• Importance:
• Each ecosystem provides unique services (e.g., forests providing timber and oxygen, wetlands filtering water).
• Supports a wide range of species and genetic diversity.
• Ensures overall ecological stability.
• Examples: Forests, grasslands, deserts, wetlands, oceans, coral reefs, mangroves.
• Impact of Loss: Habitat destruction, fragmentation, leading to loss of species and ecosystem services. For example, destruction of mangroves impacts coastal protection and fish nurseries.

2. Global Distribution of Biodiversity (Biogeography)

Biodiversity is not evenly distributed across the planet.

• Latitudinal Gradient: Generally, biodiversity is highest near the equator and decreases towards the poles. Tropical regions (e.g., Amazon rainforest, Indo-Malayan archipelago) are biodiversity hotspots.
• Reasons:
• Stable climate (less seasonal variation).
• Higher solar radiation and productivity.
• Longer evolutionary time without major glaciations.
• Greater habitat complexity.
• Altitude Gradient: Biodiversity tends to decrease with increasing altitude.
• Island Biogeography: Islands often have high endemism but are vulnerable to species loss due to their isolation and smaller areas.
• Biodiversity Hotspots:
• Definition: Regions with a high level of endemic species (found nowhere else) and significant habitat loss (at least 70% of its original natural vegetation). They are prioritized for conservation efforts.
• Criteria (developed by Norman Myers):

1. Must contain at least 1,500 species of vascular plants as endemics (plant endemism > 0.5% of global total).
2. Must have lost at least 70% of its primary vegetation.

• Global Hotspots: 36 identified globally. Examples: Western Ghats and Sri Lanka, Himalayas, Indo-Burma, Sundaland (these are also prevalent in India).

3. Value of Biodiversity (Reasons for Conservation)

Biodiversity provides numerous direct and indirect benefits, often categorized as:

• 3.1. Utilitarian Value (Direct & Indirect Use Values)
• Direct Use Values (Consumptive & Productive):
• Food: All our food crops, livestock, fish come from wild species.
• Medicine: Many important drugs are derived from plants, animals, or microorganisms (e.g., Penicillin from fungus, Aspirin from willow bark, anticancer drugs from periwinkle).
• Fuel: Wood, fossil fuels.
• Fibre: Cotton, wool, silk, timber.
• Industrial Products: Resins, gums, dyes, rubber, scents, oils.
• Indirect Use Values (Ecosystem Services):
• Pollination: By insects, birds, bats. Essential for crop production.
• Pest Control: Natural predators and parasites control agricultural pests.
• Climate Regulation: Forests absorb CO2, influence rainfall patterns.
• Water Purification: Wetlands and forests filter pollutants.
• Soil Formation & Fertility: Microorganisms, decomposers, earthworms.
• Nutrient Cycling: From decomposers to producers.
• Oxygen Production: Photosynthesis by plants.
• Waste Decomposition: By microbes and scavengers.
• Protection from Natural Disasters: Mangroves protect coastlines from storms, coral reefs from waves.
• Aesthetic & Recreational Value: Ecotourism, birdwatching, trekking, spiritual connection.

• 3.2. Ethical Value (Intrinsic Value)
• Every species has a right to exist, regardless of its utility to humans. We have a moral obligation to protect life forms.

• 3.3. Option Value
• The potential future benefits or uses of biodiversity that are currently unknown. What if a species holds the cure for a disease we haven’t encountered yet?

4. Threats to Biodiversity (The “Evil Quartet”)

The accelerated rate of species extinction primarily due to human activities is a major concern. The four major causes are often termed “The Evil Quartet.”

• 4.1. Habitat Loss and Fragmentation (The primary driver)
• Loss: Destruction of natural habitats (e.g., deforestation for agriculture, urbanization, mining, dam construction). This eliminates the living space of species.
• Fragmentation: Large, continuous habitats are broken into smaller, isolated patches.
• Consequences: Decreases population sizes, increases edge effects (more exposure to external factors like wind, invasive species), hinders movement of species, reduces genetic exchange, making populations more vulnerable.
• Example: Amazon rainforest deforestation, removal of mangroves, conversion of grasslands to farmland.

• 4.2. Over-exploitation
• Harvesting species at a rate faster than they can replenish.
• Examples: Overfishing, hunting for bushmeat, illegal wildlife trade (poaching for ivory, rhino horn, tiger parts), over-harvesting of medicinal plants.
• Consequences: Population crashes, local extinctions, commercial extinctions.

• 4.3. Alien (Exotic) Species Invasions
• When non-native species are introduced (intentionally or unintentionally) into an ecosystem, they can outcompete native species for resources, predate on them, introduce diseases, or alter habitats.
• Examples:
• Water Hyacinth (Eichhornia crassipes): Introduced for its beauty, chokes water bodies, depletes oxygen, disrupts aquatic life.
• African Catfish (Clarias gariepinus): Introduced for aquaculture, preys on native fish.
• Lantana camara: Introduced as an ornamental plant, forms dense thickets, outcompetes native vegetation.
• Parthenium hysterophorus (Carrot Grass): Invasive weed, causes allergies and reduces agricultural productivity.
• Nile Perch: Introduced into Lake Victoria, decimated cichlid fish species.

• 4.4. Co-extinctions
• When one species goes extinct, another species dependent on it also faces extinction.
• Examples:
• A specific plant pollinator going extinct leads to the extinction of the plant.
• Host fish extinction leading to the extinction of its unique parasites.
• Extinction of a prey species leading to the extinction of its predator (if it’s a specialist predator).

• Mnemonic for Evil Quartet: H.O.A.C. (Habitat Loss, Over-exploitation, Alien Species, Co-extinctions)

5. Biodiversity Conservation

Protecting biodiversity is crucial for ecological balance and human well-being. Conservation strategies are broadly classified into two types:

• 5.1. In-situ Conservation (On-site Conservation)
• Definition: Conservation of species within their natural habitats or ecosystems where they naturally occur. It’s considered the most effective way because it allows species to continue evolving and adapting.
• Methods:
• Protected Areas:
• National Parks: Areas declared by the Central/State Government for the conservation of wildlife and their environment. No human activities like grazing, forestry, or private ownership are allowed. Example: Jim Corbett National Park.
• Wildlife Sanctuaries: Areas designated for the protection of specific species or groups of species. Limited human activities (e.g., grazing, timber collection for local communities) may be permitted. Example: Periyar Wildlife Sanctuary.
• Biosphere Reserves: Internationally recognized protective areas (under UNESCO’s Man and the Biosphere Program). They aim to reconcile conservation with sustainable use. They have three zones:
• Core Zone: Strictly protected, no human interference.
• Buffer Zone: Research and educational activities permitted.
• Transition Zone: Human settlements and sustainable resource use permitted.
• Example: Nilgiri Biosphere Reserve.
• Sacred Groves: Patches of forest revered by local communities for religious or cultural reasons. They have informally protected biodiversity for centuries. Found across India (e.g., Khasi and Jaintia Hills in Meghalaya, Aravalli Hills of Rajasthan, Western Ghats of Karnataka and Maharashtra).
• Ramsar Sites (Wetlands of International Importance): Designated under the Ramsar Convention to conserve wetlands and ensure their wise use. Example: Wular Lake, Chilika Lake.
• Hotspots (as mentioned before): Identified for prioritized in-situ conservation efforts.

• 5.2. Ex-situ Conservation (Off-site Conservation)
• Definition: Conservation of species outside their natural habitats, typically in controlled environments. Used when species are critically endangered or their habitat is severely threatened.
• Methods:
• Zoological Parks (Zoos): Keep wild animals in captivity for conservation, research, and public education. Focus on breeding programs.
• Botanical Gardens: Collections of living plants for scientific study, conservation, and public display. Emphasis on rare and endangered plant species.
• Seed Banks: Store seeds of various important plant species (especially crop varieties and wild relatives) under controlled conditions (low temperature, low humidity) to preserve genetic diversity. Example: Svalbard Global Seed Vault.
• Gene Banks: Store genetic material (seeds, pollen, tissue cultures, DNA) of plants and animals.
• Cryopreservation: Preserving gametes (sperm, egg) and tissues in liquid nitrogen at very low temperatures (-196°C). These can be used for future breeding programs or genetic resurrection.
• Tissue Culture: Growing plant cells or tissues in a sterile nutrient medium for propagation, especially of rare or difficult-to-propagate species.
• Aquaria: For aquatic species conservation.

• Mnemonic for Conservation: I.E. (In-situ, Ex-situ)

6. Important Concepts & Initiatives

• IUCN Red List of Threatened Species: A comprehensive inventory of the global conservation status of biological species. It uses specific criteria to evaluate the extinction risk of thousands of species and subspecies.
• Categories: Extinct (EX), Extinct in the Wild (EW), Critically Endangered (CR), Endangered (EN), Vulnerable (VU), Near Threatened (NT), Least Concern (LC), Data Deficient (DD), Not Evaluated (NE).
• Purpose: To inform and catalyze action for biodiversity conservation, vital for policy decisions.

• Biodiversity Act, 2002 (India):
• Objective: Conservation of biological diversity, sustainable use of its components, and fair and equitable sharing of benefits arising out of the use of biological resources.
• Bodies Established: National Biodiversity Authority (NBA) at the national level, State Biodiversity Boards (SBBs) at the state level, and Biodiversity Management Committees (BMCs) at the local level.

• Convention on Biological Diversity (CBD):
• An international multilateral treaty with three main goals:

1. The conservation of biological diversity.
2. The sustainable use of its components.
3. The fair and equitable sharing of benefits arising from genetic resources.

• Adopted at the Earth Summit in Rio de Janeiro in 1992.

• Nagoya Protocol: A supplementary agreement to the CBD, which aims to implement the third objective of the CBD: the fair and equitable sharing of benefits arising out of the utilization of genetic resources.

• Endemic Species: Species found exclusively in a particular geographical area and nowhere else. Highly vulnerable to habitat loss.
• Examples in India: Lion-tailed Macaque (Western Ghats), Nilgiri Tahr (Western Ghats), Sangai Deer (Manipur).

• Keystone Species: A species that has a disproportionately large effect on its environment relative to its abundance. The ecosystem would change drastically if the keystone species were removed.
• Examples: Sea otters (control sea urchin populations, protecting kelp forests), Elephants (create clearings, disperse seeds), Wolves.

• Indicator Species: A species whose presence or absence, or population health, is used to infer the environmental conditions of a habitat. They are sensitive to environmental changes.
• Examples: Lichens (sensitive to air pollution), Frog populations (sensitive to water quality and habitat degradation).

• Flagship Species: A species chosen to represent an environmental cause, often charismatic and recognized by the public, used to garner support for conservation efforts.
• Examples: Tiger (for Project Tiger), Giant Panda (WWF symbol), Snow Leopard.

• Umbrella Species: A species whose conservation indirectly protects a large number of other species that share the same habitat. Usually, they have large area requirements or migrate seasonally.
• Example: Tiger, whose vast habitat requires conservation, thus protecting numerous co-existing species.

7. India’s Biodiversity Profile (Key Highlights)

• Mega-Diversity Nation: India is one of 17 mega-diverse countries, accounting for 7-8% of the world’s recorded species.
• Four Biodiversity Hotspots:

1. Western Ghats and Sri Lanka
2. Himalayas
3. Indo-Burma (North-East India)
4. Sundaland (includes Nicobar Islands)

• Rich Endemism: High levels of endemic flora and fauna.
• Diverse Ecosystems: Deserts, high mountains, rainforests, wetlands, coastal areas, islands.
• Project Tiger (1973): One of the most successful wildlife conservation projects, aimed at protecting tigers and their habitats.
• Project Elephant (1992): Focuses on the conservation of elephants, their habitats, and migratory corridors.
• Coastal and Marine Protected Areas: Gulf of Mannar Biosphere Reserve, Sundarbans.

This comprehensive overview covers the crucial aspects of biodiversity for competitive exams like JKSSB Forester. Focus on understanding the definitions, examples, and implications of each point for effective revision.

Editorial Team

Founder & Content Creator at EduFrugal

Email View Articles