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Biodiversity is defined as ‘the variability among living organisms from all sources, including terrestrial, marine and other aquatic ecosystems and the ecological complexes of which they are a part; this includes diversity within species, between species and of ecosystems’ – United Nations Earth Summit (1992).

Endemism is the state of a species being native to a single defined geographic location, such as an island, state, nation, country or other defined zone;
  • In our biosphere immense diversity (or heterogeneity) exists not only at the species level but at all levels of biological organization ranging from macromolecules within cells to biomes.
  • According to IUCN (2004), the total number of plant and animal species described so far is slightly more than 1.5 million.
  • More than 70 per cent of all the species recorded are animals, while plants (including algae, fungi, bryophytes, gymnosperms and angiosperms) comprise no more than 22 per cent of the total.
  • Among animals, insects are the most species-rich taxonomic group, making up more than 70 per cent of the total.
  • India accounts for nearly 7% of recorded species.
  • Largest biodiversity is found in Amazon rain forest on earth.


Patterns of Biodiversity: Latitudinal gradients: Diversity of plants and animal is not uniform throughout the world.
Species diversity decreases as we move away from the equator towards the pole.
Tropic harbour more species than temperature or polar areas


Why Tropic Account Greater Biological Diversity?

  1. Speciation: It is function of time, unlike temperate regions subjected to frequent glaciations in the past, tropical latitudes have remained relatively undisturbed for millions of years.
  2. Tropical environments, unlike temperate ones, are less seasonal, relatively more constant and predictable. Such constant environments promote niche specialization and lead to a greater species diversity.
  3. More solar energy available in the tropics, which contributes to higher productivity; this in turn might contribute indirectly to greater diversity.




Measurement of the relative frequency of each species. The number of species found in said environment.
Species richness is the number of different species represented in an ecological community, landscape or region. Species richness is simply a count of species, and it does not take into account the abundances of the species or their relative abundance distributions. Species evenness refers to how close in numbers each species in an environment is. Mathematically it is defined as a diversity index, a measure of biodiversity which quantifies how equal the community is numerically. So if there are 40 foxes and 1000 dogs, the community is not very even.
Note: Species diversity of an environment is essentially a combined measurement of richness and evenness. Sometimes, it is called the “ShannonDiversity Index.

  • ALPHA DIVERSITY: Diversity within a particular area or ecosystem, expressed by the number of species in that ecosystem.
  • BETA DIVERSITY: Comparison of diversity between ecosystems, calculated as change in amount of species between the ecosystem.
  • GAMA DIVERSITY: Measures overall diversity for different types of ecosystems within a region.




Genetic Diversity: The differences in DNA content among individuals within species and population. Allows species to adapt to changing environments. E.g. butterflies, roses, parakeets or coral in a myriad hue.
Species Diversity: Refers to the variety of living organisms on earth. For example: the western ghats have a greater amphibian species diversity than the eastern ghats.
Ecosystem/ Community Diversity: Refers to the different types of habitats. A habitat is the cumulative factor of the climate, vegetation and geography of a region. Example: deserts, forests, mangroves, coral reefs, wetlands etc.



Protection of water resources + Soils formation and protection + Nutrient storage and recycling + Pollution breakdown and absorption + Contribution to climate stability + Maintenance of ecosystems + Recovery from unpredictable events.




  • FLAGSHIP SPECIES– Species chosen to represent an environmental cause, like an ecosystem might be in need of conservation. Chosen for their Vulnerability, attractiveness or distinctiveness.
Indian tiger, the giant panda, the Golden lion, the African elephant, Asian elephant, etc.
  • KEYSTONE SPECIES: Species whose addition to or subtraction from an ecosystem leads to major changes in abundance or occurrence of at least one other species.
  • Plays role in structure, functioning or productivity of a habitat or ecosystem.
All top predators like Lion, Tiger, Crocodile, Elephant.
  • INDICATOR SPECIES: It defines trait or characteristics of the environment.
  • They are chosen as an indicator of, or proxy for, the state of an ecosystem or of a certain process within that ecosystem.
Lichens– indicators of air quality (sensitive to sulfur dioxide), Amphibians (e.g. Frog) indicates global warming and air pollution.

Fish, invertebrates, periphyton, macrophytes, etc.

  • FOUNDATION SPECIES: Dominant primary producer in an ecosystem both in terms of abundance and influence.
  • CHARISMATIC SPECIES: Large animal species with widespread popular appeal that environmental activists use to achieve conservation goals well beyond those species.
Barasingha (Bhoorsingh from kanha national park), Giant panda, The Bengal tiger, Blue whale.
  • UMBRELLA SPECIES: It acts as umbrella. Conservation of umbrella species would extend protection to other species as well.
Conservation of Tiger, efforts have been made to save the populations of wild Tigers in order to save other species that are present in the same ecosystems such as Leopards, Monkey, Hares, Boars, etc
  • INVASIVE ALIEN SPECIES OF INDIA: Species that occur outside their natural range + threaten native plants and animals or other aspects of biodiversity.

Goat weed, Alternanthera paronychioides, Prickly poppy, Palmyra, Toddy palm, Calotropis/ Madar, Swallow wort, Water Hyacinth.








Biopiracy: Practice in which indigenous knowledge of nature, originating with indigenous peoples, is used by others for profit, without authorization or compensation to the indigenous people themselves.
Bioprospecting: Systematic and organized search for useful products derived from bioresources including plants, microorganisms, animals, etc., that can be developed further for commercialization and overall benefits of the society.
Biomining: Process of using microorganisms (microbes) to extract metals of economic interest from rock ores or mine waste. Biomining techniques may also be used to clean up sites that have been polluted with metals
Bioassay: A test in which organisms are used to detect the presence or the effects of any other physical factor, chemical factor or any other type of ecological disturbance. It is very common in pollution studies; the aim is to detect lethal concentration or effective concentration causing mortality or other effects.




Botanical garden refers to the scientifically planned collection of living trees, shrubs, herbs, climbers and other plants from various parts of the world Zoo is an establishment, whether stationary or mobile, where captive animals are kept for exhibition to the public and includes a circus and rescue centers but does not include an establishment of a licensed dealer in captive animals – CZA


Die-back: Phenomena in which progressive dying of plant happens, usually backwards from the tip of any portion of plant. This is one of the adaptive mechanisms to avoid adverse conditions.


  1. Habitat loss and Fragmentation: Habitat loss due to pollution, breaking of large habitats into small fragments due to various human activities, mammals and birds requiring large territories, animals with migratory habitat are badly affected, leading to population decline.
  2. Over Exploitation: Humans have always depended on nature for food and shelter, but whgen ‘need’ turns to ‘greed’. it leads to over exploitation.
  3. Alien Species Invasions: Alien species are species that occur outside their natural range. These species when turn invasive and cause decline or extinction of indigenous species. Ex- like water hyacinth, prosopis juliflora, lantana camara etc.
  4. Co-extinctions: When a species becomes extinct, the plant and animal species associated with it in an obligatory way also become extinct.


  • India, a mega diverse country with only 2.4% of the world’s land area, accounts for 7-8% of all recorded species, including over 45,000 species of plants and 91,000 species of animals.
  • The country’s diverse physical features and climatic conditions have resulted in a variety of ecosystems such as forests, wetlands, grasslands, desert, coastal and marine ecosystems.
  • Four of 34 globally identified biodiversity hotspots: The Himalayas, the Western Ghats, the North-East, and the Nicobar Islands, can be found in India.
  • In terms of species richness, India ranks seventh in mammals, ninth in birds and fifth in reptiles.





Two ‘Realms’ Five Biomes Ten Bio-geographic Zones Twenty-five Bio-geographic provinces
Large spatial regions within which ecosystems share a broadly similar biota. Unifying features of geography and fauna and flora. Main groups of plants and animals living in areas of certain climate patterns.


It deals with geographical distribution of plants and animals.



Ecosystem or biotic subdivision of realms





1. Himalayan region represented by Palearctic realm

2. Rest of subcontinent represented by Malayan realm

1. Tropical humid forests

2. Tropical Dry or Deciduous forests

3. Warm deserts and semi deserts

4. Coniferous forest

5. Alpine meadows.


1. Trans Himalayas

2. The Himalayas

3. Desert

4. Semi-arid

5. Western ghats

6. The Deccan Peninsula

7. The Gangetic Plains

8. The Coasts

9. Northeast India

10. Islands

1A: Himalaya – Ladakh Mount.

1B: Himalaya-Tibetan Plateau

1C: Trans-Himalaya Sikkim

2A: Himalaya-North west Himalaya

2B: Himalaya-west Himalaya

2C: Himalaya-Central Himalaya

2D: Himalaya-East Himalaya

3A: Desert –Thar

3B: Desert-Kachchh

4A: Semi-arid-Punjab plains

4B: Semi-arid Punjab plains

5A: Western Ghats-Malabar plains.

5B: Western Ghats-Western Ghats Mountains

6A: Deccan Peninsular-Central Highlands

6B: Deccan Peninsular Chota Nagpur.

6C: Deccan Peninsular –Eastern Highlands

6D: Deccan Peninsular- Central Plateau

6E: Deccan Peninsular-Deccan south.

7A: Gangetic Plain-Upper Gangetic plains

7B: Gangetic Plain- Lower Gangetic Plains

8A: Coasts-West Coast

8b: Coasts- East Coast

8C: Coasts-Lakshadweep

9A: North-East Brahmaputra Valley

9B: North-East-North East Hills

10A: Islands-Andamans

10B: Islands-Nicobar



Insectivorous Plants: Plants are specialized in trapping insects. This is an adaptability mechanism of plant in nutrient poor soil.


  • The green non differentiated plants (non – differentiated into organs like root, stem and leaf) possessing chlorophyll
  • Non-green non differentiated plants characterized by total absence of chlorophyll are called Fungi.
  • Non-chlorophyllous micro-organisms which lead saprophytic or parasitic existence. Many of them are pathogenic; Saprophytic bacteria are rather beneficial.
  • A lichen is a peculiar combination of an alga and a fungus– the two live deriving mutual benefit.
  • The plant body is differentiated into a small stem and simple leaves, but true roots are absent.
  • The pteridophytes have well-differentiated plant bodies, consisting of roots, stems and leaves. Moreover, they possess vascular bundles.
  • Gymnosperms (Gymnos à naked, Sperma à seed) are the naked-seeded plants.
  • Angiosperms (Angeion à a case) are the closed-seeded plants.


Insectivorous Plants
  • Plants are specialized in trapping insects. This is an adaptability mechanism of plant in nutrient poor soil.


  • Migration refers to the regular, recurrent and cyclical seasonal movement of birds from one place to other. The distance of migration ranged from short distance to thousands of kilometers. But at the end of period, birds will eventually return to the original place.
  • Reasons for migration: To avoid extreme climatic condition + To manage food shortage + To manage shortage of water + To have a better breeding conditions + Less competition for safe nesting places.





Himalayan foothills:

Ø Flora: Natural monsoon evergreen and semi-evergreen forests; Species like Sal, giant bamboos, silk cotton trees; tall grassy meadow with savannahs in terai are dominant.
Ø Fauna: Elephant, sambar, swamp deer, cheetal, hog deer, barking deer, wild boar tiger, panther, hyena, black bear, sloth bear, Great Indian one-horned rhinoceros, wild buffalo, Gangetic gharial, golden langur

Western Himalayas (High altitude region)

Ø Flora: Natural monsoon evergreen and semi-evergreen forests; rhododendrons; dwarf hill bamboo and birch forests mixed with alpine pastures.
Ø Fauna: Tibetan wild ass (kiang), wild goats (thar, ibex) and blue sheep; antelopes (Chiru and Tibetan gazelle), deers (hangul of Kashmir stag and shou or Sikkim stag, musk deer); golden eagle, snow cocks, snow partridges; snow leopard, black and brown bears; birds like Griffon vultures.





Eastern Himalayas

Ø Flora: The Eastern Himalayas can be divided into the following climatic regions: arctic, sub-arctic, temperate, subtropical, and warm tropical. The forests are moist, dense, evergreen, semi-evergreen, or temperate. Precipitation is very high and the forest region is very humid. Sal forests and evergreen trees are found extensively all along the foothills of the Eastern Himalayas. Subtropical forests cover the hills up to an elevation of about 2000 m. Oaks, magnolias, laurels and birches covered with moss and ferns; coniferous forests of pine, fir, yew and junipers with an undergrowth of scrubby rhododendrons and dwarf bamboos; lichens, mosses, orchids, and other epiphytes dominant.
Ø Fauna: Red panda, hog badgers, forest badgers, crestless porcupines, Great one-horned rhinoceros Asian elephant ,Takin ,Wild water buffalo, Swamp Deer, Tiger Snow leopard, Clouded leopard.


Peninsula India:

Ø Flora: Sal in north and east extensions (higher rainfall) and teak in southern plateau are dominant trees. Western Ghats have evergreen vegetation (flora and fauna similar to evergreen rainforests of northeastern of India. In dry areas of Rajasthan and Aravalli hills, trees are scattered, and thorny scrub species predominate.
Ø Fauna: Elephant, wild boar, deers (cheetal or axis deer), hog deer swamp deer or barasinga, sambar, muntjac or barking deer, antelopes (four-horned antelope, Nilgiri, blackbuck, chinkara gazelle), wild dog or dhole, tiger, leopard, cheetah, lion, wild pig, monkey, striped hyena, jackal, gaur.

Indian desert

Ø Flora: Thorny trees with reduced leaves like babool, ber, khejri tree; cactus, other succulents are the main plants.
Ø Fauna: Its diverse fauna includes the great Indian bustard, blackbuck, chinkara, fox, Bengal fox, wolf, caracal, rodents, Asiatic wild ass, desert cat, red fox; reptiles (snakes, lizards and tortoise) well represented. Desert lizards include geckos.




Tropical rain forest region

Distributed in areas of Western Ghats and northeast India.

Ø Flora: Extensive grasslands interspersed with densely forested gorges of evergreen vegetation known as shoals occur in the Nilgiris (an offshoot of Western Ghats). The rain forests of the Western Ghats have dense and lofty trees with much species diversity. Mosses, ferns, epiphytes, orchids, lianas and vines, herbs, shrubs make diverse habitat. Ebony Indian rosewood, Malabar Kino, teak and Indian laurel trees predominate in these forests.

Ø Fauna: Wild elephants, gaur and other larger animals. The most prominent are hoolock gibbon (only ape found in India), golden langur, capped langur or leaf monkey, Assam macaque and the pig-tailed macaque, lion-tailed macaque, Nilgiri langur, slender loris, bats, giant squirrel, civets, flying squirrels, Nilgiri mongoose, spiny mouse.
Mangrove swamps of Sundarbans:

Ø Flora: Various species of mangroves.
Ø Fauna: In the higher regions of mangroves, there are spotted deer, pigs, monitor lizard, monkey, Royal Bengal Tiger.


Sea cow, Dugong dugon occurs in near shore waters of Gulf of Mannar, Gulf of Kachchh and Andaman and Nicobar Islands.




Species IUCN status Habitat Other information
Grey francolin Least Concern Plains and drier parts of the Indian subcontinent
Fishing Cat (Prionailurusviverrinus) Vulnerable Mangrove forests of the Sundarbans, foothills of the Himalayas along the Ganga and Brahmaputra river valleys and in the Western Ghats State Animal of West Bengal, Chilika Development Authority (CDA) designated the Fishing Cat as ambassador of Chilika Lake, Odisha.
Chinese Pink Dolphins/Indo-Pacific humpback dolphin Vulnerable Coastal waters of the eastern Indian
and western Pacific Oceans
Himalayan Brown Bears Critically endangered Highlands of the Himalayas
Dhole/Asian Wild Dog Endangered’ India has the highest number of dholes in the world
Narcondam hornbill Endangered Found only on the island of Narcondam in the Andaman Sea.
Snow Leopard Vulnerable Himalayas at elevations ranging from 3,000 to 4,500 m across Jammu and Kashmir, Ladakh, Himachal Pradesh, Uttarakhand, Sikkim, and Arunachal Pradesh
Indian Tiger or Royal Bengal Tiger (Panthera tigris) Endangered Native to the Indian subcontinent Tiger species native to India, largest populations of Bengal tigers are in India
Bullfrog (Hoplobatrachustigerinus) Least Concern It is native to the Indian subcontinent
Pinanga Andamanensis Critically endangered Endemic to the South Andaman Island. naturally occurs only in a tiny, evergreen forest pocket in South Andaman’s Mount Harriet National Park Palm species
Olive Ridley Turtles Vulnerable India’s Odisha and Andhra Pradesh coast are famous for their nesting (Gahirmatha beach, rushikulya river mouth etc are some famous sites) Performs Arribada (Synchronized, largescale neting)
Sal Forest Tortoise Critically endangered Eastern and northern India and Southeast Asia.
Brackish Water Turtle (Batagurbaska) Critically Endangered Used to be found in the river mouths of Odisha and the Sunderbans. As of now it is considered extinct in much of its former range. One of the largest turtles to be found in
Southeast Asia
Gir Lions/Asiatic lion/Panthera Leo Persica Endangered Gir National Park, Gir Sanctuary, Pania Sanctuary, Mitiyala Sanctuary and Girnar Sanctuary
Indian Gaur Vulnerable Nagarhole, Bandipur, Kabini and Masinagudi (Mudumalai)
Gee’s Golden Langur/Golden Langur (Trachypithecus geei) Endangered Endemic to the semi-evergreen and mixed-deciduous forests straddling India and Bhutan




Species Found in Other information
Trimeresurus Salazar Arunachal Pradesh A new species of green pit viper
Abortelphusa Namdaphaensis Namdapha Tiger Reserve New freshwater crab species
Spialia zebra Rajasthan Butterfly
Brahma Kamal Flower Himalaya King of Himalayan Flowers, state flower of Uttarakhand
Golden birdwing Founded in Uttarakhand India’s largest butterfly
Tetrastemma Freyae Coast of Tamil Nadu New species of marine
invertebrate i.e. ‘Tetrastemma Freyae’

IUCN status: Critically Endangered

Restricted mainly to Teesta River Valley region Researchers recently “rediscovered” this rare and critically endangered plant species
Kazi 106F India’s only Golden Tiger found in Kaziranga National Park of Assam
Schizothorax sikusirumensis New species of fish discovered in Arunachal Pradesh


  • Nanda Devi national park (Uttarakhand) – Status- World Heritage Site by UNESCO in 1988 (Nanda Devi National Park + Valley of Flowers National Park) together makes – Nanda Devi Biosphere Reserve and this reserve is recognized as UNESCO World Network of Biosphere Reserves since 2004. Species – Asiatic black bear, snow leopard, brown bear and blue sheep etc
  • Dehing Patkai Elephant Reserve (Assam) Why in news? National Board for Wild Life (NBWL) has recommended coal mining in a part of this reserve.
  • Panna Tiger Reserve (Madhya Pradesh) = New entry into world network of biosphere reserves (WNBR) under MAB Programme. Presently, there are 18 notified biosphere reserves in India of which 12 are recognized under MAB Program.
  • Eravikulam National Park (Kerala) à It houses the special Neelakurinji flowers Strobilantheskunthianam) that bloom once every 12 years. The park holds the largest viable population of the endangered NilgiriTahr.
  • Gorumara National Park = West Bengal
  • Dehing Patkai Wildlife Sanctuary (Assam): – Referred as ‘The Amazon of East’
  • Melghat Tiger Reserve (Maharashtra)
  • India’s 1st Lichen Park (Uttarakhand)
‘Animal Discoveries 2019’ and ‘Plant Discoveries 2019’ = Annual Publication released
by Zoological Survey of India (ZSI) and the Botanical Survey of India (BSI) respectively.

  • Sphaerotheca Magadha: burrowing frog discovered in farm fields of Jharkhand.
  • Amomum nagamiense: A wild ginger variety, discovered from the forest behind Kohima Zoo in Nagaland.
  • Pteris subiriana: A wild fern, found not just in Kerala but also Tamil Nadu and Maharashtra
  • Cnemaspis anandani: A rock-dwelling gecko, endemic to the Western Ghats
  • Enoplotrupes tawangensis: a dung beetle from Tawang, Arunachal Pradesh.

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 Career Development Program 2023 Result PDF     Download UPSC Mains 2023 Question Papers PDF  Free Initiative links -1) Download Prahaar 3.0 for Mains Current Affairs PDF both in English and Hindi 2) Daily Main Answer Writing  , 3) Daily Current Affairs , Editorial Analysis and quiz ,  4) PDF Downloads  UPSC 2022 Final Result🔥5 out of Top 10 from PW OnlyIAS Community. UPSC Prelims 2023 Trend Analysis cut-off and answer key