BIODIVERSITY IN INDIA

1. Realms

Realms are the large spatial regions within which ecosystems share a broadly similar biota. Realm is a continent-sized area with unifying features of geography, flora and fauna.

The large areas of Earth’s surface within which organisms have been evolving in relative isolation over long periods, separated from one another by geographic features like oceans, broad deserts or high mountain ranges that constitute barriers to migration.

Indian region is composed of two realms.

1. The Himalayan region is represented by Pale-arctic Realm.
2. The rest of the country is represented by the Malayan Realm.

There are 8 terrestrial biogeographic realms on earth. Nearctic realm, palearctic realm, Africotropical realm, Oceania realm, Indo-Malayan realm, Australian Realm, Neotropical realm, Antarctic realm.

2. Biomes

The term biome defines the main groups of plants, and animals living in areas of certain climate patterns. It includes how animals, plants and soil interact together. The plants and animals living in the area are adapted to that environment. India has 5 biomes.

1. Warm deserts and semi-deserts
2. Tropical humid forests
3. Tropical dry or deciduous forests including monsoon forests
4. Alpine meadows
5. Coniferous forests

3. Bio-geographic zones

Biogeography deals with the geographical distribution of plants and animals. There are 10 biogeographic zones which are distinguished in India. They are-

• Himalayas- The entire mountain chain running from north-western to north-eastern India, comprising a diverse range of biotic provinces and biomes, 7.2% of the country’s landmass.
• Trans-Himalayas- An extension of the Tibetan plateau, harbouring high-altitude cold desert in Ladakh(J&K) and Lahaul Spiti comprising 5.7% of the country’s landmass.
• Desert- The extremely arid area west of the Aravali hill range, comprising both the salty desert of Gujarat and the sand desert of Rajasthan, comprising 6.9% of the country’s landmass.
• Semi-arid- The zone between the desert and the Deccan plateau, including the Aravali hill range, occupying 15.6% of the country’s landmass.
• Western ghats- The hill ranges and plains running along the western coastline, south of the Tapati River, covering an extremely diverse range of biotic provinces and biomes. 5.8% of the country’s landmass.
• Coasts- A large coastline distributed both to the west and east, with differences between them. Lakshadweep islands are included in this with the percent area being negligible.
• Deccan Peninsula- The largest zone, covering much of the southern and south-central plateau with predominantly deciduous vegetation. 4.3% of the country’s geographic area.
• Gangetic plain- It is defined by the Ganges river system. These plains are relatively homogenous occupying 11% of the country’s landmass.
• North-East India- The plains and non-Himalayan hill ranges of the northeastern part of India, with a wide variation of vegetation. It occupies 5.2% of the country’s landmass.
• Islands- The Andaman & Nicobar Islands in the Bay of Bengal are highly diverse occupying 0.03% of the country’s landmass.

Branches

The biogeography is divided into two branches.

1. Phytogeography- It is also known as plant geography. It deals with the origin, distribution and environmental interrelations of plants.
2. Zoogeography- It is also known as animal geography. It deals with the migration and distribution of animals.

4. Bio-geographic Provinces

•  Bio-geographic Province is an ecosystematic or biotic sub-division of realms. India is divided into 25 bio-geographic zones.
• Biogeographic classification of India was done by Rodgers and Panwar(1988), describing 10 biogeographic zones in India, further divided into 25 biogeographic provinces.
• The classification was done using various factors like altitude, moisture, topography, rainfall etc.
• Biogeographic zones were used as a basis for planning wildlife-protected areas.

5. Flora

India ranks 10^th in the world and 4^th in Asia, in terms of floral diversity. Nearly 11% of the world’s known flora is present in India.

Floral Diversity

Algae

• The green non-differentiated plants with chlorophyll are known as Algae.
• Non-differentiated here means are categorized into organs like roots, stems, leaves etc.
• They usually grow on moist, damp surfaces and water.
• The freshwater algae are generally green or blue-green, whereas the marine algae are of different colours like red, brown etc.
• They are all autotrophic as they prepare their food material.
• The study of algae is called “Algalogy”.
• Spirogyra (green algae), gracilaria(red algae), sargassum(brown algae).

Fungi

• Fungi are non-differentiated, non-chlorophyllous plants.
• They grow either on dead, rotten organic matter as Saprophytes or live as parasites on other living hosts.
• Moulds and mushrooms are familiar examples of saprophytic fungi.
• The maximum diversity of fungi is in the Western Ghats followed by the eastern Himalayas.
• Penicillium and bread mould are common examples of fungi.

Bacteria

• Non-chlorophyllous microorganisms which lead to saprophytic or parasitic existence are considered bacteria.
• Many of them are pathogenic, saprophytic bacteria are beneficial.
• They are soil-borne and many of them are used in industries.
• Pseudomonas and streptococcus are some of the bacteria.

Lichens

• Lichen is a mutual relationship of an algae and fungus that live together for a mutual benefit.
• They are a group of greyish-green plants which grow on rocks, tree trunks, dead wood etc.
• The algae manufactures food which becomes available to the fungus and absorbs and retains water thus keeping the algal cell moist. This is a classic example of symbiosis.
• They are most common in wetlands, rare in rivers and streams and are not found in groundwater.

Bryophytes

• The plant body of a bryophyte is differentiated into a small stem, simple leaves and true roots are absent.
• They are usually found in moist places, examples include liverworts and mosses.
• Bryophytes are the 2^nd largest group of green plants in India distributed largely in Eastern Himalayas, North-eastern India, Western Himalayas and western ghats.
• Mosses constitute the major component of Indian bryophytes followed by liverworts and hornworts.

Pteridophytes

• The pteridophytes have well-differentiated plat bodies with roots, stems, and leaves.
• They also possess vascular bundles.
• Most of them are terrestrial plants flourishing well in moist, shady places and some of them are aquatic.
• Pteridophytes include vascular cryptograms like club mosses, horse-tails, and ferns which are universally distributed.
• The northeastern region including the Eastern Himalayas is rich in pteridophytic diversity, followed by south India and north India.

Gymnosperms

• Literally gymnosperms means naked-seeded plants- gymnos- naked, sperma- seed.
• They have very simple flowers without accessory whorls and stamens, carpels remain aggregated in cones.
• Ovules are present on the surface of the carpels and are directly pollinated by the pollen grains.
• There is nothing like an ovary, style, or stigma and naturally, there is no fruit.
• Pine is the largest family in gymnosperms.
• Gnetum and Cycas are mostly confined to the North Eastern region, Eastern & Western Ghats, Andaman & Nicobar Islands.

Angiosperms

• Literally angiosperms means covered seeds. Angion means container/vessel, and sperma means seeds.
• These are the most highly developed plants which bear flowers having conspicuous accessory and essential whorls.
• Carpels have an ovary, style, and stigma.
• With the stimulus of fertilization, the ovary usually develops into the fruit and the ovules into seeds.
• So the seeds remain within the fruits.
• India has more than 7% of the world’s known flowering plants.

Endemism

• Endemism is the state of species being found in a single defined geographic location.
• In peninsular India, including western & eastern ghats, more than 2,600 species of flora are present.
• Eastern Himalayas and the north-eastern region, 2500 species are present.
• North-western Himalayas contain 800 species of plants.
• Andaman & Nicobar Islands have 250 species of flora.

Crop Genetic Diversity

Agriculture is one of the dominant drivers and mainstay of economic growth in India. The large mosaic of distinct agroecosystems is characterized by variations in edaphic, climatic and geographic features. These features contributed to diverse cropping patterns and systems across the country.

The national gene bank at the National Bureau of Plant Genetic Resources (NBPGR), Delhi is primarily responsible for the conservation of unique accessories on a long-term basis, as base collections for posterity, predominantly in the form of seeds.

India stands 7^th in the world in terms of contribution of species to agriculture and animal husbandry.

Livestock genetic diversity

• India contains vast resources of livestock and poultry, that play a key role in rural livelihood security. In terms of population, India ranks 1^st in buffaloes, 2^nd in cattle and goats, 3^rd in sheep, 4^th in ducks, 5^th in chickens and 6^th in camels in the world.
• The genetic resources of farm animals in India are represented by a broad spectrum of native breeds of cattle, buffaloes, goats, sheep, swine, equines, camel, and poultry.
• Over the years, animal husbandry has intensified in India with the widespread introduction of exotic breeds. This led to the reduction in total genetic variability & population size of many local breeds.
• The majority of the domestic livestock (85%) in India is reared under low-input production systems.

6. Fauna

The animal kingdom is classified into vertebrates and invertebrates based on the presence of a vertebral column(backbone).

Invertebrates

Animals with no backbone are considered as invertebrates. More than 98% of animal species in the world are invertebrates. Internal skeleton made of bane is absent in invertebrates. Many invertebrates have fluid-filled, hydrostatic skeletons like jellyfish or worms. Others have a hard outer shell like insects and crustaceans.

Porifera

• They are also known as sponges.
• They are marine, primitive multicellular animals with water transport or canal systems.
• They are hermaphrodites ;-sexes are not separate.
• Sycon, freshwater sponge, and spongin are common examples.

 Coelenterata

• They are also known as cnidarians.
• The name cnidaria is derived from the presence of special cells called cnidoblasts/cnidocytes.
• They are aquatic radially symmetrical animals.
• Some cnidarians like corals have calcium carbonate skeletons.
• Polyp and Medusa are two body forms of cnidarians.
• Hydra, physalis, and gorgonia are common examples.

 Ctenophora

• They are commonly known as sea walnuts or comb jellies.
• Bioluminescence is their special character.
• The body of an individual bears eight external rows of ciliated comb plates.
• Pleurobrachia and ctenoplana are common examples.

 Platyhelminthes

• They are commonly known as flatworms.
• They are mostly end0parasites  in animals including human beings.
• Flame cells help in osmoregulation and excretion.
• Regeneration capacity is high.
• Planaria, tapeworm(taenia), Liver fluke(fasciola) are common examples.

 Aschelminthes

• They are commonly known as roundworms, as their body is circular in cross-section.
• They have an organ system level of organization.
• Alimentary canal is complete with muscular pharynx.
• Often females are larger than males.
• Ascaris(round worm), wuchereria(filarial worm), are common examples.

 Annelids

• The body of annelids is divided into segments, each segment is called a metamere.
• They may be aquatic or terrestrial.
• Internal organs are very well developed and found almost anywhere in the world.
• Earthworms and leeches are common examples.

 Arthropods

• This is the largest phylum in the animal kingdom, including insects.
• They have limbs with joints which allow them to move.
• The external skeleton called the exoskeleton is present protecting the internal organs.
• Insects, crustaceans, and arachnids are included in this phylum.

Insects

• Insects have an exoskeleton that covers their entire body.
• The body is divided into three regions- cephalus(head), thorax, abdomen;6legs, antennae.
• Beetles, butterflies, moths, cockroaches, dragonflies, bees, wasps, etc are common examples.

Crustaceans

• They are mostly marine animals.
• Crustaceans have a hard, external shell which protects their body.
• Crabs, lobsters, and prawns are common examples.

Arachnids

• Arachnids have 4pairs of legs and the body has two distinguished parts.
• They do not have antennae.
• Commonly known arachnids are spiders, scorpions, ticks & mites.

Molluscs

• Molluscs have soft skin-like organs covered with hard outer shells.
• Some of them are terrestrial like snails, slugs etc.
• Some molluscs are aquatic like oysters, mussels, clams, squid, octopus etc.

Echinoderms

• Echinoderms are marine which live in oceans.
• Most echinoderms have arms or spines that radiate from the centre of their body.
• Common echinoderms are sea stars, sea urchins, sand dollars, sea cucumber, Starfish etc.

Hemichordata

• A small group of worm-like marine animals are present in this phylum.
• Their body is cylindrical with an anterior proboscis, collar and long trunk.
• Gills are present for respiration.
• Balanoglossus and saccoglossus are common examples.

Vertebrates

Vertebrates animals with backbones and spinal cords. They are the most advanced organisms on earth. Although vertebrates represent only a very small percentage of all animals, their size & mobility often allow them to dominate their environment.

Pisces

• Commonly known as fishes.
• They are cold-blooded, aquatic.
• Breathe through gills, lungs are absent.
• They have scales, fins.
• They are oviparous-laying eggs.
• Catfish, shark, and pufferfish are common examples.

Amphibians

• They can live on both land and water.
• They are cold-blooded with webbed feet.
• They breathe with lungs and gills.
• Their skin is soft and moist which helps in respiration (cutaneous respiration ).
• Four-limbed, oviparous animals.
• Frogs and salamanders are common examples.

Reptiles

• The name refers to crawling, creeping organisms.
• They are cold-blooded, mostly terrestrial with scales all over their body.
• Skin is usually dry, ears are replaced by earholes.
• They are oviparous.
• Snakes, lizards, crocodiles, and tortoises are common examples.

Aves

• They are commonly known as birds.
• Birds are warm-blooded with feathers and wings.
• Bipedal animals with ear holes and oviparous.
• Their body is adapted for flight like a streamlined body, reduced body parts etc.
• Ostrichs, crows, penguins, and parrots are common examples.

Mammals

• The special character of mammals is the presence of mammary glands to feed their young ones.
• The body of the mammals is covered with hair.
• Sweat glands and sebaceous glands are present.
• They are warm-blooded and breathe with lungs.
• Mammals that live on land have 4 limbs and ears to stick out.
• They directly give birth to young ones- viviparous.
• Bat(flying mammal), whale(aquatic mammal), platypus(egg laying mammal), human are common examples.

7. Wildlife in India

India’s forest land nurtures more than 500 species of mammals and more than 2000 bird species. India is one of the most diverse regions of the world and contains three of the world’s 36 biodiversity hotspots-western ghats, eastern Himalayas, and the Indonesia-Burma hot spot.

7.1. Himalayan Mountain System

The west Himalayas have low rainfall, and heavy snowfall whereas in the east Himalayas, there is heavy rainfall and snowfall only at very high altitudes. At lower altitudes conditions are similar to the tropical rain forests. Biodiversity in both Himalayas differs.

•  Natural monsoon evergreen and semi-evergreen forests;
•  Dominant species are Sal, silk cotton trees, giant bamboo;
•  Tall grassy Meadow with Savannah in Tarai.

• Oaks, magnolias, laurels, birches covered with Moss and ferns;
• Coniferous forests of pine, fir, yew, Junipers with undergrowth of scrubby rhododendrons and dwarf bamboos;
•  Lichens, Moses, orchids and other epiphytes are dominant.

 Natural monsoon Evergreen and semi Evergreen forests;

 Rhododendrons, dwarf hill bamboo, and birch forests mixed with Alpine pastures.

 7.2. Peninsular- India

 It has two zones-  Peninsular India and its extension into the drainage basin of the Ganga river system; and the Desert region of Rajasthan- the Thar of the Indian desert region.

• Sal in the north and east extensions( Higher rainfall) and teak in the southern plateau are dominant trees.
•  Western gods have Evergreen vegetation- flora and fauna similar to Evergreen rainforests of northeast India.
• In dry areas of Rajasthan and Aravali hills, trees are scattered and thorny scrub species predominate.
•  The forests give way to more open Savannah habit.

 Tropical rainforest region

• It is distributed in western gods and northeast India.
• Extensive grasslands interspersed with densely forested gorges of evergreen vegetation known as sholas occur in the Nilgiris.
• Sholas also occur in Aanaimalia & Palani hills.
• The rainforest of the western ghats has dense and lofty trees with much species diversity.
• Moses, ferns, epiphytes, orchids, lianas, vines, herbs, and shrubs make diverse habitats.
• Ebony trees predominate in these forests.
• A variety of tropical orchids are found.
• Stratification in rainforests is very distinct.

 Andaman and Nicobar Islands: These islands are home to tropical rainforests. Giant dipterocarpus, Terminalia, lagerstroemia are dominant. Mangroves are also distributed in coastal areas.

 Mangroves

•  Sundarbans are the delta of the Ganges where both the Ganges and Brahmaputra join and drain into the Bay of Bengal.
•  The lower tidal zones are pioneer trees like Soneratia and Avicennia. Above this zone, there are rhizophora, bruguiria, and excaecaria-coreopsis forests.
•  Above this level there are supporting forests of phoenix in association with excaecaria.
•  There are heriteria forests In the highest portion with thick undergrowth of phoenix.