World Distribution of Plants and Animals

• The world distribution of plants (phytogeography) and animals (zoogeography) is the patterned, non-random arrangement of flora and fauna over the Earth’s surface.
  • It is produced by present-day environmental controls acting on the deep evolutionary and tectonic history of the continents.
• The pattern is zonal: vegetation belts change latitudinally from the equator to the poles and altitudinally from sea level to the tree-line and snow-line on high mountains.
  • Similar climates recur at different latitudes and altitudes, so comparable plant and animal assemblages reappear wherever those conditions are repeated: the founding insight of classical biogeography.
• Biogeographers divide the land into floristic kingdoms and regions for plants and faunal (zoogeographical) regions and realms for animals, on the basis of shared, endemic taxa rather than climate alone.

Controls and Approaches

Geography Optional Notes {PDF}

Complete Notes Package (Paper I & II) | 3000+ Pages | Instant Download

Discounted Price | Buy Now @ ₹1,180 →

Factors controlling distribution

• The distribution of plants, and of the animals that depend on them, is controlled by eight interacting groups of factors:
  • climatic (sunlight, temperature, moisture and humidity, precipitation, soil moisture);
  • edaphic (soil nutrients, texture, structure, acidity and alkalinity, soil profile);
  • biotic (grazing, human use, competition, mutualism, parasitism, natural selection);
  • physical (relief, slope angle, gradient, slope aspect);
  • tectonic (continental drift, plate movement, volcanicity, earthquakes);
  • fire (lightning fires, and deliberate or accidental human fires);
  • dispersal of seeds and spores by wind, water, animals and people;
  • human interference (deforestation, plantation, urbanisation, agriculture, species introduction).
• These work at two levels, set out fully among the factors influencing world distribution of plants and animals:
  • Ecological (present-day) factors set the limits within which a species can live: thermal limits and growing season, moisture regime (xerophytes, mesophytes, hydrophytes), photoperiod, altitudinal zonation and rain-shadow contrasts.
  • Historical factors explain why similar climates carry different species: the break-up of Gondwanaland and Laurasia, barriers of ocean, desert and mountain, and isolation on islands.
• Barriers and history make the regions below distinct. Southern beech (Nothofagus) in South America, New Zealand and Australia is the classic Gondwanan disjunction, explained by continental drift.
  • Island faunas are poor because immigration falls with distance and extinction rises as area shrinks, the equilibrium idea of Robert MacArthur and Edward O. Wilson (1963, 1967).

Approaches to studying plant distribution

• By habitat: terrestrial and aquatic plants studied separately.
• By floral divisions: floristic kingdoms, sub-kingdoms, regions and provinces, based on endemic families, genera and species.
• By latitudinal and altitudinal extent: belts from the equator to the poles and from the foothills to the snow-line.
• By the features of plant communities: life-forms, dominant species and canopy structure, the basis of the biomes of the world.

World Distribution of Plants

Floristic divisions of the world

• A floristic kingdom is the highest unit of plant geography: a large area whose flora shares endemic families and many endemic genera. Kingdoms are divided into sub-kingdoms, regions and provinces.
• Floristic schemes rest on taxonomy and history, not climate. California, central Chile, the Cape and south-west Australia share a Mediterranean climate and look alike, yet fall in different kingdoms.
• Main schemes:

Ronald Good’s six floristic kingdoms

• Ronald Good (1947), in The Geography of the Flowering Plants, grouped the world’s land flora into six floristic kingdoms and 37 regions. His scheme remains the standard framework for floral regions.
• The Boreal (Holarctic) kingdom is the largest, the Cape kingdom the smallest. Only the Palaeotropical kingdom is split into sub-kingdoms.

1. Australian Kingdom

• It covers the whole of Australia, dominated by one genus, Eucalyptus.
  • Eucalypts are so dominant that eucalypt forest makes up about three-quarters of Australia’s native forest.
  • There are more than 800 species, ranging from tall, shady giants such as the mountain ash to dwarf, multi-stemmed mallee of the dry interior.
• Gondwanan origin: eucalypts belong to the myrtle family (Myrtaceae), whose relatives are widespread in South America. Fossil eucalypts about 52 million years old from Patagonia show the genus once spread across a joined southern continent.
• The kingdom’s endemic flora evolved through long isolation after Australia drifted away from Antarctica and the other southern continents.
• Human dispersal: eucalyptus has been planted on almost every continent.
  • In India it lines railways and roads and fills farm and social-forestry plantations, often regardless of local suitability, which has fed debate on its heavy water use.

2. Cape Kingdom

• It occupies only the south-western tip of Africa, about 90,000 km², yet is one of the richest floras on Earth.
  • It holds about 9,000 plant species, about 69% of them endemic, in less than 0.5% of Africa’s area: nearly a fifth of the continent’s flora. Its protected areas are a UNESCO World Heritage Site (2004).
• Typical plants are cryptophytes: their buds survive in bulbs and tubers buried in the soil, from which new shoots rise after the dry summer or a fire.
• Many are garden flowering plants, such as Lobelia, red-hot pokers (Kniphofia), Erica, Freesia, Gladiolus and Pelargonium. European colonists carried them to gardens worldwide.
• Fynbos is the natural vegetation: sclerophyllous shrubs a few metres tall over herbaceous undergrowth, adapted to a Mediterranean climate and periodic fire.
  • Proteas, ericas and reed-like restios dominate; many species need fire or smoke to release or germinate their seeds.
  • True forest survives only in small, fire-protected patches in moist ravines.
• Threat: the native range keeps shrinking as farmland, vineyards, plantations and towns replace it, and invasive pines and wattles spread; over 1,700 Cape plant species are threatened.

3. Antarctic Kingdom

• A narrow, broken strip on the edge of the Southern Ocean, from southern Chile and Patagonia to the sub-Antarctic islands and New Zealand.
  • Its signature tree is Nothofagus, the southern beech, whose shared range is evidence of former Gondwanan links.
• New Zealand’s native vegetation:
  • Tussock grasslands, with some sedges and dicotyledonous shrubs, dominate the drier east and the uplands.
    • Short tussock grasslands: mainly Festuca and Poa, up to about 0.5 m, yellow-grey.
    • Tall tussock grasslands: mainly snow tussocks (Chionochloa).
  • Warm temperate forests mix conifers of the Podocarpaceae, Cupressaceae and Araucariaceae (kauri) with flowering trees, chiefly Nothofagus.
  • Subtropical forests of the north are evergreen, with a dense cover of tall trees over several distinct layers.
• Human modification: Polynesian and then European settlement cleared much forest. Introduced mammals, mainly grazing red deer and rabbits, destabilised plant communities and caused severe soil and gully erosion.

4. Palaeotropical Kingdom

• It includes most of Africa, Madagascar, the Saharo-Arabian and Thar deserts, India, South-East Asia, southern China, New Guinea and the Pacific islands.
• Three sub-kingdoms:
  • African sub-kingdom: tropical Africa, Madagascar and the North African-Indian desert belt;
  • Indo-Malaysian sub-kingdom: India, Sri Lanka, continental South-East Asia, the Malay Archipelago and New Guinea;
  • Polynesian sub-kingdom: the Pacific islands, including Hawaii, Fiji and New Caledonia.
• Regions include the West African rainforest, Madagascar, the Indian region and the Malaysian region. Plants vary greatly from region to region, though a few genera are common to all the sub-kingdoms.
• Gondwanan links: Africa, Madagascar and India share many old lineages, while the Malay Archipelago mixes Asian and Australian elements.

5. Neotropical Kingdom

• It covers South and Central America, the Caribbean and tropical Mexico, except southern Chile and Patagonia.
• A few genera are shared with tropical Africa because the early flowering plants spread across the two continents in the Cretaceous, when they were still joined in Gondwanaland.
  • Sea-floor spreading in the Atlantic then drove South America westward, and separate evolution produced the present contrasts between the two floras.
• Characteristic families: cacti and bromeliads (almost wholly American), with rubber, cacao, cinchona and the Amazon water lily.

6. Boreal (Holarctic) Kingdom

• It includes North America except Central America, Greenland, all of Europe, North Africa and Asia north of the Himalaya, with the Arctic.
• It is the most extensive kingdom: the northern continents were joined across the Bering land bridge and the North Atlantic for much of the Tertiary, so their floras are closely related.
• Regions include:
  • Arctic and Sub-Arctic Region (ASAR): tundra and the northern taiga;
  • Euro-Siberian Region (ESR): the broadleaf and coniferous forests of Europe and Siberia;
  • Mediterranean Region (MR): the winter-rain lands round the Mediterranean Sea;
  • Irano-Turanian Region (ITR): the steppes and deserts of Anatolia, Iran and Central Asia;
  • East Asian Region (EAR), Good’s Sino-Japanese region: China, Japan and the Himalaya;
  • Atlantic North American Region (ANAR): the eastern forests and prairies;
  • Rocky Mountain Region (RMR), Good’s Pacific North American region: the western mountains and coast.

Takhtajan’s kingdoms and the 2023 map

• Armen Takhtajan (1986) kept six kingdoms but renamed and refined them:
  • Holarctic (Boreal, Tethyan or Ancient Mediterranean, and Madrean sub-kingdoms), Palaeotropical, Neotropical, Cape, Australian and Holantarctic.
  • He placed the Western Himalaya in the Irano-Turanian region and the Eastern Himalaya in the Eastern Asiatic region, both Holarctic; peninsular India forms the Indian region of the Palaeotropical kingdom.
• A 2023 phylogenetic map of 12,664 flowering-plant genera recognised eight floristic realms.
  • It keeps the Holarctic, Neotropical and Australian realms but drops the Palaeotropical, Antarctic and Cape kingdoms as units: the Saharo-Arabian flora becomes a realm of its own, and the Cape is merged into an African realm.
  • Most realms formed after the Palaeogene, and plate-tectonic isolation, not climate, drove their separation.

Newbigin’s floral regions

• Marion Isabel Newbigin (1869–1934), a Scottish biologist and geographer, set out her scheme in Plant and Animal Geography (1936), published after her death.
• Climate first: many plant orders are almost wholly tropical, and woody forms dominate the tropics while herbs dominate temperate lands. So botanists run their main divisions across the globe as belts.
  • Floristic affinity second: special regions are then separated off from the two great belts.
• Her five floral regions:

• Pantropic belt: tropical Africa and tropical Asia are close, while tropical America differs, so botanists split it into Old and New World sections.
  • A few genera, such as the trees Vismia and Symphonia, occur in West Africa and tropical America only, a hint of a past link between Africa and Brazil.
• Northern Palaeotropical Desert: few species but mostly endemic, showing that aridity came slowly enough for new species to evolve.
  • Botanists treat the southern Sahara as a transition linking Mediterranean and tropical floras, whereas zoologists simply draw a straight line across the desert.
• Austral region: whether it is one interrupted region or three (South American, South African, Australian) is debatable.
  • Plants show southern links that mammals cannot, because South Africa has no marsupials and Australia had no native placentals.
• Intercalated regions: the Desert and Mediterranean regions are “intercalated” floral regions with no zoological equivalent. Elsewhere botanists and zoologists broadly agree.

The Mediterranean floral region

• Extent: wider than the climatologist’s region. It covers the Mediterranean shores, the northern fringe of the Sahara and Persia, with vague limits in the east.
  • Saharan massifs act as a floral divide: Mediterranean plants on their northern slopes, endemic desert plants on the southern.
• Climatic control: winter rain and summer drought (the Cs climate of the Köppen classification) make drought, not cold, the limiting season.
• Vegetation: sclerophyllous evergreens with small, leathery, waxy leaves that cut water loss.
  • Trees: holm oak (Quercus ilex), cork oak, olive, Aleppo pine and, in the east, cedars of Lebanon.
  • Maquis is dense evergreen scrub. Under fire and grazing it degrades to garrigue, low aromatic shrubs such as rosemary, thyme, lavender and Cistus.
  • Bulbs and annuals escape the summer drought; many shrubs resprout after fire.
• Refugia: the region lay outside the Pleistocene ice sheets. The Balkans sheltered plants through glaciation; the Judas tree (Cercis siliquastrum) spread westward again from there as the climate improved.
  • Such survivals are common among plants but rare among mammals, which scattered or died out. So the region is a floral unit but not a zoological one: the Barbary macaque of the Atlas belongs to an Asian genus, while the rock hyrax of Syria is African.
• Today: the Mediterranean Basin biodiversity hotspot holds about 25,000 plant species, more than half endemic.
  • The basin is warming about 20% faster than the global average, with longer droughts and fire seasons, which threatens its relict endemics.
• Similar climates elsewhere: California, central Chile, the Cape and south-western Australia share the climate and the convergent sclerophyll form, but Newbigin placed them in her Holarctic and Austral regions. History, not climate alone, fixes floristic boundaries.

World Distribution of Animals

Studying animal distribution

• Animal distribution is studied in two ways:
  • species level: the range of all members of one species, divided into distributional areas by abundance;
  • community level: the whole population of all species in a given region.
• Animal patterns are more complex than plant patterns because animals are mobile. Apart from humans and their commensals, no animal species is universally distributed.

Principles of land-animal distribution

• Environment sets numbers and diversity. Vertebrate diversity peaks on the land and in the fresh waters of the tropics.
• Distribution is zonal, in horizontal (latitudinal) and vertical (altitudinal) zones.
  • Latitude controls the horizontal zones: sunlight, and with it vegetation and its diversity, declines towards the poles, so species diversity falls from the equator to the poles.
• Tropical origin and outward spread: in the classical view of Philip Jackson Darlington Jr. (1957), many groups arose in the tropics and spread outward, so higher-latitude faunas formed by dispersal, migration and successive speciation.
  • The temperate zone is in this sense a “subtracted” tropical fauna: groups dropped out along the way.
  • Animals radiated in all directions from their centres of origin, so faunas are arranged in concentric zones.
• Any region’s diversity reflects several phases of dispersal and colonisation.
• Regional concentration is clearest among mammals; other classes are more widespread and less region-specific, which is why faunal regions are drawn mainly on mammals and birds.
• Continuous and discontinuous ranges:
  • Continuous: the moose (elk in Europe) occupies an unbroken belt of taiga across North America and Eurasia.
  • Discontinuous (disjunct): the azure-winged magpie, the weather fish and the bitterling occur in western Europe and in East Asia, separated by a wide gap.
    • The Iberian magpie population has been a separate species, Cyanopica cooki, since 2002: long isolation turns a disjunct range into new species.
• Oceanic islands carry special faunas because ocean barriers keep immigration low.
  • Hawaii, volcanic and never joined to any continent, had no native amphibians, land reptiles or land mammals except one bat, the Hawaiian hoary bat. Its only native freshwater fishes are a handful of gobies descended from marine ancestors.

From Sclater to Wallace: the faunal regions

• A zoogeographical (faunal) region is a large area whose animals share endemic families and genera and differ markedly from those of other regions. Its limits follow long-standing barriers such as oceans, deserts and mountains, not present climate.
• Philip Lutley Sclater (1858) first divided the world into six regions from the distribution of birds.
• Alfred Russel Wallace (1876), in The Geographical Distribution of Animals, applied them to all vertebrates, with four sub-regions each. His division remains the most convincing and widely accepted: Palaearctic, Nearctic, Oriental, Ethiopian, Australian and Neotropical.
• Later classifications of world fauna:

Huxley’s three realms

• Thomas Henry Huxley (1868) grouped the regions into larger realms, dividing the world across the latitudes rather than between Old and New Worlds:
  • Arctogaea (“northern land”) joined the Palaearctic, Nearctic, Ethiopian and Oriental regions;
  • Notogaea (“southern land”) at first included South America with Australia and New Zealand.
• Later writers, among them William Thomas Blanford (1890), separated South America as Neogaea (“new land”), giving the three realms now linked with Huxley’s name.

• Notogaea is unique for what never arrived. It has no native cats, dogs, hoofed mammals or primates.
  • Monotremes (platypus and echidnas), the only egg-laying mammals, live only in Australia and New Guinea. Marsupials radiated into the niches placentals fill elsewhere: kangaroos as grazers, the koala as a leaf-eater, wombats as burrowers, the sugar glider as a flying-squirrel twin.
  • Birds: flightless emu, cassowaries and kiwi; lyrebirds, bowerbirds, birds-of-paradise and mound-building megapodes.
  • Reptiles and fish: the tuatara, last survivor of an otherwise extinct order, and the Queensland lungfish.
  • The only native land placentals are bats, rodents that island-hopped from Asia in the last few million years, and the dingo, brought by people a few thousand years ago.

Wallace’s six faunal regions

1. Palaearctic Region

• It covers Europe, North Africa and the Sahara, and Asia north of the Himalaya: the largest region, mostly temperate and cold.
• Characteristic animals: Russian desmans, dormice, mole rats, saiga and the chiru (Tibetan antelope), and the accentors, the region’s own bird family. Reptiles are few in the cold north.
• Five sub-regions by vegetation:

• Fauna of the region: 136 vertebrate families, 100 mammal genera and 174 bird genera; 3 families and 35 mammal and 57 bird genera are found nowhere else.

2. Nearctic Region

• It covers North America south to the Mexican plateau, and Greenland.
• Close kinship with the Palaearctic: the two were joined by the Bering land bridge in the Tertiary and repeatedly in the Pleistocene, when sea level fell.
  • Animals crossed freely: American and European bison interbreed, and both regions share salmon, trout, wolves, lynx, moose and reindeer (caribou).
  • Hence many zoologists merge the two into one Holarctic region.
• Exchange across Beringia ran both ways:
  • Horses and camels evolved in North America and crossed into Asia. Horses then died out in the Americas about 10,000–12,000 years ago and were reintroduced by the Spanish in the 16th century.
  • Bison, moose, elk, bighorn sheep and mountain goats came from Asia across the bridge. Domestic pigs, goats and sheep were brought by Europeans.
• Endemic and characteristic fauna: pronghorn, pocket gophers, pocket mice and kangaroo rats, the mountain beaver, the wild turkey, mole salamanders and the bowfin. Reptiles are numerous in the south.
• Fauna of the region: 122 vertebrate families, 74 mammal genera and 169 bird genera, with 12 families and 24 mammal and 52 bird genera unique.
• Five sub-regions by vegetation:

• Southern mixing: in the south-west (the Sonoran zone) northern mammals mingle with Neotropical ones such as the armadillo, peccary and opossum, which moved north after the Panama isthmus closed about 3 million years ago.

3. Oriental Region

• It covers South Asia and South-East Asia with the western Malay Archipelago and the Philippines; almost all of it is tropical, so its fauna is close to the Ethiopian.
• Transition zones: the Himalaya, the Tibetan Plateau and the mountains of China separate it from the Palaearctic; the East Indies (Wallacea) separate it from the Australian region.
• Fauna of the region: 164 vertebrate families, 118 mammal genera and 340 bird genera, with 12 families, 55 mammal genera and 165 bird genera unique.
• Dominant animals: Asian elephant, rhinoceroses, many deer and antelopes (nilgai, blackbuck), gaur, tiger, sun bear, porcupines, pheasants and jungle fowl, gibbons, monkeys, lizards and snakes such as the king cobra.
• Signature animals: tree shrews, gibbons, orang-utan, tarsiers, colugos (flying lemurs) and the Malayan tapir.
• Wallace’s four sub-regions: Indian, Ceylonese, Indo-Chinese and Indo-Malayan.

4. Ethiopian Region

• It covers Africa south of the Sahara, south-western Arabia across the Red Sea, and Madagascar; most of it is tropical.
• Absences mark it out: there are no moles, beavers, bears, wild camels or deer.
• Fauna of the region: 174 vertebrate families (22 unique), 140 mammal genera (90 unique) and 294 bird genera (179 unique): the most vertebrate families and mammal genera of any region.
• Three sub-regions by vegetation:

• Shared with the Oriental region: elephants, lions, cheetahs, rhinoceroses and pangolins.
• Found only here: hippopotamus, giraffe and okapi, aardvark, ostrich, elephant shrews and golden moles, with the secretary bird, shoebill and turacos.
  • Madagascar, separate from Africa for about 160 million years, has its own lemurs, tenrecs and fossa.
• Adaptations: savanna grazers migrate with the rains (the Serengeti wildebeest migration); desert antelopes such as the oryx tolerate high body temperatures and drink little; forest primates and the okapi are adapted to dense, layered canopy.

5. Australian Region

• It covers Australia, Tasmania, New Guinea, the islands east of Wallace’s line, and New Zealand with the Pacific islands (Wallace’s Polynesian sub-region). Some zoologists treat New Zealand separately.
• Marsupials dominate. The region’s native mammals are marsupials and monotremes; placental mammals are confined to bats, rodents and the dingo.
  • Marsupials carry their young in a pouch containing the teats. Close to 70% of the world’s marsupial species live here.
• Fauna of the region: 141 vertebrate families (22 unique), 72 mammal genera (44 unique) and 298 bird genera.
• Three sub-regions by vegetation:

• Its western limit, Wallace’s line, has long been debated.

6. Neotropical Region

• It covers South America, Central America, tropical Mexico and the Caribbean, mostly tropical.
• It has the largest number of exclusive mammals:
  • Edentates (Xenarthra): sloths, anteaters and armadillos;
  • New World monkeys, many with prehensile tails, and marmosets;
  • caviomorph rodents: capybara, cavies, agoutis, chinchillas, viscacha;
  • vampire bats and American marsupials: the opossums, shrew opossums and the monito del monte, quite different from Australian marsupials.
• Birds: 683 bird genera, 576 of them unique, the highest avian endemism of any region: hummingbirds, toucans, rheas, tinamous and the hoatzin.
• Fauna of the region: 168 vertebrate families (44 unique) and 130 mammal genera (103 unique).
• Three sub-regions by vegetation:

• Great American Biotic Interchange: when the Isthmus of Panama closed, about 3 million years ago, armadillos and opossums moved north while cats, dogs, deer, camels (llamas) and tapirs moved south.

Wallace’s line, Weber’s line and Wallacea

• Wallace’s line separates the Oriental and Australian faunas. Alfred Russel Wallace (1859) drew it through the Lombok Strait between Bali and Lombok and the Makassar Strait between Borneo and Sulawesi, then between the Philippines and the Sangihe–Talaud islands.
  • Bali and Lombok are only about 35 km apart, yet their birds and mammals differ sharply because the strait is deep.
  • Thomas Henry Huxley (1868) named it, and swung its northern part west of the Philippines, a variant called Huxley’s line.
• Why the line exists: in the Pleistocene ice ages sea level fell by up to about 120 m.
  • The shallow Sunda Shelf became dry land, joining Sumatra, Java, Borneo and Bali to Asia (Sundaland). The Sahul Shelf joined New Guinea, the Aru Islands and Tasmania to Australia (Sahul).
  • The islands between were never joined to either, so only good dispersers crossed.
• Wallacea is this transition zone, about 347,000 km² of land: Sulawesi, the Lesser Sunda Islands (Lombok to Timor) and the Moluccas.
  • Its fauna is mixed and highly endemic: Sulawesi has the anoa, babirusa, macaques and tarsiers alongside two cuscus marsupials; the Komodo dragon lives on Komodo and Flores.
• Weber’s line is the line of faunal balance, where Oriental and Australian elements are about equal.
  • It runs between Sulawesi and the Moluccas and between Timor and the Kai and Tanimbar islands, well east of Wallace’s line.
  • Max Carl Wilhelm Weber, leader of the Dutch Siboga Expedition (1899–1900), concluded from fishes, molluscs and mammals that Wallace’s line lay too far west. Paul Pelseneer (1904) named the boundary after him.
• Lydekker’s line, drawn by Richard Lydekker (1896), follows the edge of the Sahul Shelf, west of New Guinea and the Aru Islands: the eastern limit of Wallacea.
• Current view: the lines are different boundaries for different groups, not rival answers. Mammals and birds change sharply at Wallace’s line, while many insects and plants change more gradually across Wallacea.

Isolated island faunas

• Some zoologists give “minor faunal region” status to islands long isolated from any mainland, though how complete that isolation has been through geological time is debated.

• On such islands birds and insects radiate into roles mammals fill elsewhere: New Zealand’s kākāpō and the extinct moa grazed like mammals. Isolation also makes them the most extinction-prone faunas.

Classical regions and modern realms

• Wallace’s six regions map closely onto today’s biogeographic realms:
  • Oriental → Indomalayan, Ethiopian → Afrotropical, Australian → Australasian; Palaearctic, Nearctic and Neotropical keep their names.
  • The modern WWF scheme of eight realms separates Oceania and Antarctica. The Sahara and most of Arabia fall in the Palearctic, and the Indus plains in the Indomalayan realm.
• Ben Holt and colleagues (2013) used the phylogeny and ranges of over 21,000 vertebrate species to define 11 realms, splitting off Panamanian, Saharo-Arabian, Sino-Japanese, Madagascan and Oceanian realms: Wallace’s outline survived the test of genetic data.

Indian Context

• Floristic position: most of India lies in the Palaeotropical kingdom (Indo-Malaysian sub-kingdom). The Himalaya is Boreal: the Western Himalaya with the Irano-Turanian flora, the Eastern Himalaya with the Sino-Japanese.
  • Altitudinal zonation repeats the latitudinal sequence on one slope: Gangetic plains → Bhabar and Terai → subtropical → temperate → alpine → nival.
• Faunal position: India lies in Wallace’s Oriental region (the Indomalayan realm), with the Himalaya a transition to the Palaearctic. It draws on four faunal sources:
  • Palaearctic: snow leopard, Tibetan wild ass (kiang), chiru and wild yak in Ladakh;
  • Ethiopian: the Asiatic lion of Gir, the striped hyena and ratel, and the cheetah, reintroduced from Namibia and South Africa to Kuno National Park (2022–23);
  • Indo-Malayan: the hoolock gibbon (India’s only ape), binturong and clouded leopard of the north-east;
  • Gondwanan relicts: the purple frog of the Western Ghats, whose nearest relatives live in the Seychelles.
• Biodiversity hotspots: India shares four of the world’s 36: the Himalaya, Indo-Burma, the Western Ghats and Sri Lanka, and Sundaland (through the Nicobar Islands).
  • Endemism: the Western Ghats hold endemics such as the Nilgiri tahr and lion-tailed macaque, illustrating concentration and isolation on a continental-margin scale, comparable in logic to Madagascar. Endemism is highest in such isolated hills and islands.
• Shrinking ranges: the tiger (3,682 in the 2022 estimate, about three-quarters of the world’s wild tigers) and the Great Indian Bustard, now confined mostly to the Thar, are tracked through IUCN Red List categories, the policy face of distribution change in wildlife conservation.

International framework