Full study notes for BEVAE-181 Block 2 Unit 6. Covers the definition of biodiversity (Rio 1992), coins by Lovejoy and Wilson, three levels of biodiversity (genetic, species, ecosystem), known species table (Box 6.1), ecosystem stability and diversity, all ten biogeographic zones of India with flagship wildlife, 34 global biodiversity hot spots, India's four hot spots (Western Ghats, Indo-Burma, Himalayas, Sundaland), why India is a mega-diversity country, and the full classification of use values (direct extractive/non-extractive, indirect, non-use — option, bequest, existence). Includes seven SVG diagrams, SAQs and terminal question answers. Free PDF download.
Unit 6 · Index
Earth's biodiversity took over 3,000 million years to evolve and forms the basis for the survival of all life on our planet. This unit defines biodiversity, explains its three levels, explores all 10 biogeographic zones of India with their wildlife, identifies the 34 global hot spots (including India's 4), explains why India is a mega-diversity country, and analyses the use values of biodiversity.
Earth's biodiversity has taken more than 3,000 million years to evolve. It forms the basis for survival of the human species and other life forms on our planet. When we speak of global biodiversity, we speak of the totality of genetic strains, species, and ecosystems in the entire world.
Biodiversity is the diversity of and in living nature. The word "diversity" at its heart implies the number of different kinds of objects, such as species. However, defining and measuring biodiversity is complex.
📌 Who coined the terms? "Biological diversity" was coined by Thomas Lovejoy (1980). "Biodiversity" was coined by E.O. Wilson. Biodiversity = totality of genes, species, and ecosystems of a region.
Biodiversity is "The variability among living organisms from all sources, including, inter alia, terrestrial, marine and other aquatic ecosystems and the ecological complexes of which they are part: this includes diversity within species, between species and of ecosystems."
Biodiversity is "The variability among living organisms from all sources, including terrestrial, marine and other aquatic ecosystems and the ecological complexes of which they are part: this includes diversity within species, between species and of ecosystems." — Earth Summit, Rio de Janeiro, 1992. The term "biological diversity" was coined by Thomas Lovejoy (1980) and "biodiversity" by E.O. Wilson.
There are three levels of diversity — genetic, species, and ecosystem. These levels cannot be separated; each interacts with and influences the others. A change at one level causes changes at other levels.
Species diversity means the differences between species (both domesticated and wild). It is the most visible component of biodiversity. There are different estimates of existing species: ~12.5 million is the most widely accepted. Of these, only 1.7 million species have been described. Insects and micro-organisms are the most abundant life forms on Earth.
| Group | Known Species | Notable Fact |
|---|---|---|
| Viruses | 5,000 | Smallest life forms |
| Bacteria | 4,000 | Most ancient organisms |
| Fungi | 70,000 | Key decomposers |
| Plants | 270,000 | 62% found in tropical rainforests! |
| Insects | 960,000 | ~600,000 are beetles alone! |
| Invertebrates (excl. insects) | 400,000 | — |
| Fish | 22,000 | — |
| Amphibians and Reptiles | 12,000 | — |
| Birds | 10,000 | — |
| Mammals | 4,500 | Humans are 1 of 4,500! |
| TOTAL DESCRIBED: | ~1.7 million of estimated 12.5 million | |
A complex ecosystem (high diversity) has many food web links. Eliminating one species has little effect — other links compensate. In a simple ecosystem, losing one species can collapse the whole system. Higher diversity = greater stability and resilience.
Genetic Diversity: Diversity of hereditary information (genes) found within a species. Different varieties of same species (e.g. different rice or mango varieties). Genetic diversity is the "fundamental currency of diversity" — allows a species to adapt to changing environmental conditions (lower rainfall, higher temperature).
Species Diversity: Differences between species (both domesticated and wild). Most visible component of biodiversity. About 12.5 million species estimated globally; only 1.7 million described. Insects are most abundant (960,000 species, of which ~600,000 are beetles). Measured by number of species in an area.
India is divided into 10 biogeographic zones by W.A. Rodgers and H.S. Panwar of the Wildlife Institute of India (1988). Each zone has a distinctive set of physical, climatic, and historical conditions, and represents major species groupings.
Classification developed by W.A. Rodgers and H.S. Panwar (1988), Wildlife Institute of India
| Zone | Name | Key Features & Flagship Wildlife |
|---|---|---|
| Z-1 | Trans-Himalayas | Area: ~1,86,200 sq.km. Ladakh & Lahul-Spiti. Altitude 4,500–6,000m. Extremely fragile. World's richest wild sheep & goat communities (8 species). Wildlife: Wild Yak, Tibetan Ass, Tibetan Gazelle, Ibex, Tibetan Antelope, Snow Leopard, Indian Wolf, Pallas's Cat (endemic), Black-necked Crane (migratory). |
| Z-2 | The Himalayas | Stretches 2,000+ km east to west. One of India's richest zones. Sub-tropical foothills (Chir Pine, Ban Oak) → Temperate (Maple, Walnut, Moru Oak, Fir, Spruce) → Sub-alpine (Birch, Rhododendrons). Western: Deodars, Blue Pine. Eastern: Mishmi Takin. High endemism in all groups. |
| Z-3 | Indian Desert (Thar) | West Gujarat and west Rajasthan. Wildlife unique for extraordinary ecological adaptations. Desert Fox, Desert Cat, Houbara Bustard, Sand Grouse — all endemic to Thar. Common trees: Prosopis cineraria, Salvadora oleoides. |
| Z-4 | Semi-Arid | Area: 5,08,000 sq.km (15% of India). Strong links with Pakistan, Iran, Middle East, North Africa. Flora: Acacia sp. Fauna: Blackbuck, Chowsingha, Gazelle, Nilgai, Sloth Bear, Lesser Florican. |
| Z-5 🔥 | Western Ghats (Hot Spot!) | Area: ~1,60,000 sq.km. ~2/3 of India's endemic plants found here. Tropical evergreen forests (1/3 of total area). Endemic species: Nilgiri Langur, Lion-tailed Macaque, Spiny Dormouse, Nilgiri Tahr, Malabar Grey Hornbill, Malabar Civet, Rusty Spotted Cat. Also: Tiger, Leopard, Dhole, Sloth Bear, Elephant, Gaur. |
| Z-6 | Deccan Peninsula | Largest zone — ~43% of India's land mass (~14,21,000 sq.km). Deciduous forests, thorn forests, degraded shrublands. Fauna (widespread): Chital, Sambar, Nilgai, Chowsingha, Barking Deer, Gaur, Blackbuck. Small populations of Elephant and Wild Buffalo at MP/Maharashtra/Odisha junction. |
| Z-7 | Gangetic Plain | Area: ~3,59,400 sq.km. One of the most fertile areas in the world. Most land under cultivation. Small populations: Nilgai, Blackbuck, Chinkara. Wetlands/rivers: Mugger and Gharial Crocodile, Gangetic Dolphin (Platanista gangetica), rich freshwater turtle community (20+ species). |
| Z-8 | North-East India | Transition zone between India, Indo-Malayan, and Indo-Chinese regions. One of the most important zones for biodiversity and endemism. Brahmaputra valley: Rhinoceros, Buffalo, Swamp Deer, Hog Deer, Pygmy Hog, Hispid Hare, largest elephant populations in India. Major migratory bird flyway (Siberia/China ↔ India). |
| Z-9 | The Islands | Andaman & Nicobar (348 islands in Bay of Bengal) + Lakshadweep (Arabian Sea). High endemism. Of India's 15,000 flowering plants, 2,200 found here; 200+ strict endemics. Mammals impoverished (isolation) — rodents and bats dominate. |
| Z-10 | The Coasts | Coastal stretch: ~5,689 km. West: Arabian Sea (Gujarat to Kerala). East: Bay of Bengal (Bengal to Tamil Nadu). 5 communities: Mangroves, Sandy beaches, Mud flats, Raised corals, Marine angiosperm pastures. Wildlife: Dugong, Hump-back Dolphin, Estuarine Crocodile, 5 sea turtle species, Sundarban Tiger. |
Hot spots are areas that are extremely rich in species, have high endemism, and are under constant threat.
📊 What 34 Hot Spots contain on just 1.4% of Earth's land surface: 44% of all vascular plants · 35% of vertebrates (excl. fish) · 96% of world's most threatened primate species
These 4 hot spots extend into neighbouring countries — Western Ghats/Sri Lanka, Indo-Burma/Eastern Himalayas, Himalayas, and Sundaland (Nicobar Islands). All are rich in floral wealth and endemism — not just flowering plants but also reptiles, amphibians, swallow-tailed butterflies, and mammals.
Some countries are richer in biodiversity than others. Generally, economically poor developing countries in tropical areas are richer in biodiversity than developed countries in temperate areas. Countries with vast bioresources are called Mega-Diverse countries. India is one of 18 such countries.
🌿 Also: 3 Biomes — tropical humid forests, tropical deciduous forests, and warm deserts/semi-deserts. India has 49,219 plant species, of which 5,150 are endemic and distributed in 141 genera under 47 families — corresponding to about 30% of the world's recorded flora.
India qualifies as a mega-biodiversity country because of:
Determining the value of biodiversity is complex and often debated — because the worth placed on biodiversity reflects underlying human values, which vary dramatically among societies and individuals.
Resources extracted and consumed directly. Examples: Timber harvesting, fishing, collecting medicinal plants, hunting for food. Important in agriculture, medicine (pharmaceuticals), and industry (rubber, dyes).
Resource is used WITHOUT extraction or removal. Examples: Bird watching, wildlife photography, scientific research in an ecosystem, eco-tourism. The resource remains intact for others to use.
People visit national parks, botanical and zoological gardens, aquaria to experience natural landscapes. People maintain home gardens. Art, music, and literature inspired by nature.
Species inspire songs, stories, folktales, dance, poetry, traditional crafts, cuisines, local rituals, and place names. Example: Hanuman langur (Semnopithecus entellus) is considered sacred in India.
Every species has a natural right to exist, independent of its use to humans. Humans are only 1 of ~12.5 million species. Each species is unique and the result of millions of years of evolution without human intervention.
Nutrient cycling, pollination, climate regulation, soil formation, water purification — provided "free" by biodiversity. Without these, Earth would be uninhabitable. These are non-consumptive values.
Value based on potential future use — conserving biodiversity in the hope it could be used directly or indirectly in the future as a source of genetic material, pharmaceuticals, or crop enhancement.
Value of conserving biodiversity for future generations — even if the current generation never directly uses it. We have a responsibility to preserve the natural heritage for our children.
Value based purely on the continued existence of a species — irrespective of whether it will ever be used. The mere knowledge that tigers or blue whales exist has value, even to people who will never see them.
Direct Use Values: Values for goods directly consumed. Can be: (a) Extractive — timber harvesting, fishing, medicinal plant collection, hunting; (b) Non-extractive — bird watching, wildlife photography, scientific research (resource remains intact). Important in agriculture (crop varieties, genetic improvement), medicine (antibiotics, anticancer drugs from nature), and industry (rubber, dyes, resins).
Indirect Use Values: Values for services that support consumed items: (a) Aesthetic — beauty of nature inspires recreation and art; (b) Cultural and religious — species in songs, stories, rituals, cuisines (e.g., Hanuman langur sacred in India); (c) Ethical — every species has a right to exist independent of human use; (d) Non-consumptive ecosystem services — nutrient cycling, pollination, climate regulation, water purification, soil formation — services without which Earth would be uninhabitable.
Exam-style questions from the IGNOU textbook.
Definition (Rio 1992): Biodiversity is "The variability among living organisms from all sources, including terrestrial, marine and other aquatic ecosystems and the ecological complexes of which they are part: this includes diversity within species, between species and of ecosystems."
Three Levels:
India has 10 biogeographic zones (Rodgers & Panwar, 1988). Key wildlife per zone:
Hot spots are identified based on three criteria:
Use Values:
Non-Use Values: Option (potential future use), Bequest (for future generations), Existence (value from knowing species exist).
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