![Ecozone Indomalaya](https://upload.wikimedia.org/wikipedia/commons/8/8c/Ecozone_Indomalaya.svg)
The Indomalayan realm is one of the eight
biogeographic realm
A biogeographic realm or ecozone is the broadest biogeographic division of Earth's land surface, based on distributional patterns of terrestrial organisms. They are subdivided into bioregions, which are further subdivided into ecoregions.
De ...
s. It extends across most of
South and
Southeast Asia
Southeast Asia, also spelled South East Asia and South-East Asia, and also known as Southeastern Asia, South-eastern Asia or SEA, is the geographical south-eastern region of Asia, consisting of the regions that are situated south of mainlan ...
and into the southern parts of
East Asia
East Asia is the eastern region of Asia, which is defined in both Geography, geographical and culture, ethno-cultural terms. The modern State (polity), states of East Asia include China, Japan, Mongolia, North Korea, South Korea, and Taiwan. ...
.
Also called the Oriental realm by
biogeographers, Indomalaya spreads all over the
Indian subcontinent
The Indian subcontinent is a list of the physiographic regions of the world, physiographical region in United Nations geoscheme for Asia#Southern Asia, Southern Asia. It is situated on the Indian Plate, projecting southwards into the Indian O ...
and
Southeast Asia
Southeast Asia, also spelled South East Asia and South-East Asia, and also known as Southeastern Asia, South-eastern Asia or SEA, is the geographical south-eastern region of Asia, consisting of the regions that are situated south of mainlan ...
to lowland southern
China, and through
Indonesia
Indonesia, officially the Republic of Indonesia, is a country in Southeast Asia and Oceania between the Indian and Pacific oceans. It consists of over 17,000 islands, including Sumatra, Java, Sulawesi, and parts of Borneo and New Guine ...
as far as
Sumatra,
Java
Java (; id, Jawa, ; jv, ꦗꦮ; su, ) is one of the Greater Sunda Islands in Indonesia. It is bordered by the Indian Ocean to the south and the Java Sea to the north. With a population of 151.6 million people, Java is the world's mos ...
,
Bali, and
Borneo
Borneo (; id, Kalimantan) is the third-largest island in the world and the largest in Asia. At the geographic centre of Maritime Southeast Asia, in relation to major Indonesian islands, it is located north of Java, west of Sulawesi, and ea ...
, east of which lies the
Wallace line
The Wallace Line or Wallace's Line is a faunal boundary line drawn in 1859 by the British naturalist Alfred Russel Wallace and named by English biologist Thomas Henry Huxley that separates the biogeographical realms of Asia and Wallacea, a trans ...
, the realm boundary named after
Alfred Russel Wallace which separates Indomalaya from
Australasia
Australasia is a region that comprises Australia, New Zealand and some neighbouring islands in the Pacific Ocean. The term is used in a number of different contexts, including geopolitically, physiogeographically, philologically, and ecologi ...
. Indomalaya also includes the
Philippines
The Philippines (; fil, Pilipinas, links=no), officially the Republic of the Philippines ( fil, Republika ng Pilipinas, links=no),
* bik, Republika kan Filipinas
* ceb, Republika sa Pilipinas
* cbk, República de Filipinas
* hil, Republ ...
, lowland
Taiwan
Taiwan, officially the Republic of China (ROC), is a country in East Asia, at the junction of the East and South China Seas in the northwestern Pacific Ocean, with the People's Republic of China (PRC) to the northwest, Japan to the nort ...
, and
Japan's
Ryukyu Islands
The , also known as the or the , are a chain of Japanese islands that stretch southwest from Kyushu to Taiwan: the Ōsumi, Tokara, Amami, Okinawa, and Sakishima Islands (further divided into the Miyako and Yaeyama Islands), with Yona ...
.
Most of Indomalaya was originally covered by forest, and includes
tropical and subtropical moist broadleaf forests
Tropical and subtropical moist broadleaf forests (TSMF), also known as tropical moist forest, is a subtropical and tropical forest habitat type defined by the World Wide Fund for Nature.
Description
TSMF is generally found in large, discon ...
, with
tropical and subtropical dry broadleaf forests
The tropical and subtropical dry broadleaf forest is a habitat type defined by the World Wide Fund for Nature and is located at tropical and subtropical latitudes. Though these forests occur in climates that are warm year-round, and may receive ...
predominant in much of India and parts of Southeast Asia. The
tropical forest
Tropical forests (a.k.a. jungle) are forested landscapes in tropical regions: ''i.e.'' land areas approximately bounded by the tropic of Cancer and Capricorn, but possibly affected by other factors such as prevailing winds.
Some tropical fore ...
s of Indomalaya are highly variable and diverse, with economically important trees, especially in the families
Dipterocarpaceae and
Fabaceae.
Major ecological regions
The
World Wildlife Fund
The World Wide Fund for Nature Inc. (WWF) is an international non-governmental organization founded in 1961 that works in the field of wilderness preservation and the reduction of human impact on the environment. It was formerly named the Wo ...
(WWF) divides Indomalayan realm into three bio-regions, which it defines as "geographic clusters of eco-regions that may span several habitat types, but have strong biogeographic affinities, particularly at taxonomic levels higher than the species level (genus, family)".
Indian subcontinent
The
Indian subcontinent
The Indian subcontinent is a list of the physiographic regions of the world, physiographical region in United Nations geoscheme for Asia#Southern Asia, Southern Asia. It is situated on the Indian Plate, projecting southwards into the Indian O ...
bioregion covers most of
India
India, officially the Republic of India (Hindi: ), is a country in South Asia. It is the seventh-largest country by area, the second-most populous country, and the most populous democracy in the world. Bounded by the Indian Ocean on the so ...
,
Bangladesh
Bangladesh (}, ), officially the People's Republic of Bangladesh, is a country in South Asia. It is the eighth-most populous country in the world, with a population exceeding 165 million people in an area of . Bangladesh is among the mos ...
,
Nepal
Nepal (; ne, :ne:नेपाल, नेपाल ), formerly the Federal Democratic Republic of Nepal ( ne,
सङ्घीय लोकतान्त्रिक गणतन्त्र नेपाल ), is a landlocked country in S ...
,
Bhutan
Bhutan (; dz, འབྲུག་ཡུལ་, Druk Yul ), officially the Kingdom of Bhutan,), is a landlocked country in South Asia. It is situated in the Eastern Himalayas, between China in the north and India in the south. A mountainou ...
, and
Sri Lanka and eastern parts of
Pakistan
Pakistan ( ur, ), officially the Islamic Republic of Pakistan ( ur, , label=none), is a country in South Asia. It is the world's fifth-most populous country, with a population of almost 243 million people, and has the world's second-lar ...
. The
Hindu Kush
The Hindu Kush is an mountain range in Central and South Asia to the west of the Himalayas. It stretches from central and western Afghanistan, Quote: "The Hindu Kush mountains run along the Afghan border with the North-West Frontier Province ...
,
Karakoram,
Himalaya
The Himalayas, or Himalaya (; ; ), is a mountain range in Asia, separating the plains of the Indian subcontinent from the Tibetan Plateau. The range has some of the planet's highest peaks, including the very highest, Mount Everest. Over 100 ...
, and
Patkai
The Pat-kai (Pron:pʌtˌkaɪ) or Patkai Bum ( Burmese: ''Kumon Taungdan'') are a series of mountains in the Indo-Myanmar border falling in the north-eastern Indian states of Arunachal Pradesh, Nagaland and Upper Burma region of Myanmar. The ...
ranges bound the bioregion on the northwest, north, and northeast; these ranges were formed by the collision of the northward-drifting Indian subcontinent with Asia beginning 45 million years ago. The Hindu Kush, Karakoram, and Himalaya are a major biogeographic boundary between the subtropical and tropical flora and fauna of the Indian subcontinent and the temperate-climate
Palearctic realm.
Indochina
The Indochina bioregion includes most of mainland
Southeast Asia
Southeast Asia, also spelled South East Asia and South-East Asia, and also known as Southeastern Asia, South-eastern Asia or SEA, is the geographical south-eastern region of Asia, consisting of the regions that are situated south of mainlan ...
, including
Myanmar
Myanmar, ; UK pronunciations: US pronunciations incl. . Note: Wikipedia's IPA conventions require indicating /r/ even in British English although only some British English speakers pronounce r at the end of syllables. As John Wells explai ...
,
Thailand
Thailand ( ), historically known as Siam () and officially the Kingdom of Thailand, is a country in Southeast Asia, located at the centre of the Indochinese Peninsula, spanning , with a population of almost 70 million. The country is b ...
,
Laos,
Vietnam
Vietnam or Viet Nam ( vi, Việt Nam, ), officially the Socialist Republic of Vietnam,., group="n" is a country in Southeast Asia, at the eastern edge of mainland Southeast Asia, with an area of and population of 96 million, making i ...
, and
Cambodia
Cambodia (; also Kampuchea ; km, កម្ពុជា, UNGEGN: ), officially the Kingdom of Cambodia, is a country located in the southern portion of the Indochinese Peninsula in Southeast Asia, spanning an area of , bordered by Thailan ...
, as well as the subtropical forests of southern
China.
Sunda Shelf and the Philippines
Malesia
Malesia is a biogeographical region straddling the Equator and the boundaries of the Indomalayan and Australasian realms, and also a phytogeographical floristic region in the Paleotropical Kingdom. It has been given different definitions. Th ...
is a botanical province which straddles the boundary between Indomalaya and Australasia. It includes the
Malay Peninsula and the western Indonesian islands (known as
Sundaland), the Philippines, the eastern Indonesian islands, and New Guinea. While the Malesia has much in common botanically, the portions east and west of the
Wallace Line
The Wallace Line or Wallace's Line is a faunal boundary line drawn in 1859 by the British naturalist Alfred Russel Wallace and named by English biologist Thomas Henry Huxley that separates the biogeographical realms of Asia and Wallacea, a trans ...
differ greatly in land animal species; Sundaland shares its fauna with mainland Asia, while terrestrial fauna on the islands east of the Wallace line are derived at least in part from species of Australian origin, such as
marsupial
Marsupials are any members of the mammalian infraclass Marsupialia. All extant marsupials are endemic to Australasia, Wallacea and the Americas. A distinctive characteristic common to most of these species is that the young are carried in a ...
mammals and
ratite birds.
History
The flora of Indomalaya blends elements from the ancient supercontinents of
Laurasia and
Gondwana. Gondwanian elements were first introduced by India, which detached from Gondwana approximately 90
MYA, carrying its Gondwana-derived flora and fauna northward, which included
cichlid fish and the plant families
Crypteroniaceae and possibly
Dipterocarpaceae. India collided with Asia 30-45 MYA, and exchanged species. Later, as
Australia-New Guinea
The continent of Australia, sometimes known in technical contexts by the names Sahul (), Australia-New Guinea, Australinea, Meganesia, or Papualand to distinguish it from the country of Australia, is located within the Southern and East ...
drifted north, the collision of the Australian and Asian plates pushed up the islands of
Wallacea
Wallacea is a biogeographical designation for a group of mainly Indonesian islands separated by deep-water straits from the Asian and Australian continental shelves. Wallacea includes Sulawesi, the largest island in the group, as well as ...
, which were separated from one another by narrow straits, allowing a botanic exchange between Indomalaya and
Australasia
Australasia is a region that comprises Australia, New Zealand and some neighbouring islands in the Pacific Ocean. The term is used in a number of different contexts, including geopolitically, physiogeographically, philologically, and ecologi ...
. Asian rainforest flora, including the dipterocarps, island-hopped across Wallacea to New Guinea, and several Gondwanian plant families, including
podocarp
Podocarpaceae is a large family of mainly Southern Hemisphere conifers, known in English as podocarps, comprising about 156 species of evergreen trees and shrubs.James E. Eckenwalder. 2009. ''Conifers of the World''. Portland, Oregon: Timber Pr ...
s and
araucarias, moved westward from Australia-New Guinea into western Malesia and Southeast Asia.
Flora
The subfamily
Dipterocarpoideae
Dipterocarpaceae is a family (biology), family of 16 genera and about 695 known species of mainly tropical lowland rainforest trees. The family name, from the type genus ''Dipterocarpus'', is derived from Greek language, Greek (''di'' = two, ''pt ...
comprises characteristic tree species in Indomalaya's moist and seasonally dry forests, with the greatest species diversity in the moist forests of
Borneo
Borneo (; id, Kalimantan) is the third-largest island in the world and the largest in Asia. At the geographic centre of Maritime Southeast Asia, in relation to major Indonesian islands, it is located north of Java, west of Sulawesi, and ea ...
. Teak (''
Tectona'') is characteristic of the seasonally dry forests of the Indomalaya, from India through Indochina, Malaysia, and the Philippines. Tropical pitcher plants (''
Nepenthes'') are also characteristic of Indomalaya, and the greatest diversity of species is in Sumatra, Borneo, and the Philippines.
The tropical forests of Indomalaya and Australasia share many lineages of plants, which have managed over millions of years to disperse across the straits and islands between Sundaland and New Guinea. The two floras evolved in long isolation, and the fossil record suggests that Asian species dispersed to Australasia starting 33 million years ago as Australasia moved northwards, and dispersal increased 12 million years ago as the two continents approached their present positions. The exchange was asymmetric, with more Indomalayan species spreading to Australasia than Australasian species to Indomalaya.
Fauna
Two orders of mammals, the
colugo
Colugos () are arboreal gliding mammals that are native to Southeast Asia. Their closest evolutionary relatives are primates. There are just two living species of colugos: the Sunda flying lemur (''Galeopterus variegatus'') and the Philippine fly ...
s (Dermoptera) and
treeshrew
The treeshrews (or tree shrews or banxrings) are small mammals native to the tropical forests of South and Southeast Asia. They make up the entire order Scandentia, which split into two families: the Tupaiidae (19 species, "ordinary" treeshrew ...
s (Scandentia), are
endemic
Endemism is the state of a species being found in a single defined geographic location, such as an island, state, nation, country or other defined zone; organisms that are indigenous to a place are not endemic to it if they are also found else ...
to the realm, as are families Craseonycteridae (
Kitti's hog-nosed bat
Kitti's hog-nosed bat (''Craseonycteris thonglongyai''), also known as the bumblebee bat, is a near-threatened species of bat and the only extant member of the family Craseonycteridae. It occurs in western Thailand and southeast Myanmar, where i ...
),
Diatomyidae
Diatomyidae is a family of hystricomorph rodents. It is represented by a single living species, ''Laonastes aenigmamus,'' native to Laos in Southeast Asia. Fossil species are known from the Oligocene and Miocene of Asia and eastern Europe.
"Laz ...
,
Platacanthomyidae
The rodent family Platacanthomyidae, or Oriental dormice, includes the spiny dormice and the Chinese pygmy dormice. In spite of their appearance, these animals are not true dormice, but are part of the large and complex superfamily Muroidea. ...
, Tarsiidae (
tarsiers) and Hylobatidae (
gibbons). Large mammals characteristic of Indomalaya include the
leopard,
tiger
The tiger (''Panthera tigris'') is the largest living cat species and a member of the genus ''Panthera''. It is most recognisable for its dark vertical stripes on orange fur with a white underside. An apex predator, it primarily preys on ...
s,
water buffalos,
Asian elephant
The Asian elephant (''Elephas maximus''), also known as the Asiatic elephant, is the only living species of the genus ''Elephas'' and is distributed throughout the Indian subcontinent and Southeast Asia, from India in the west, Nepal in the no ...
,
Indian rhinoceros
}
The Indian rhinoceros (''Rhinoceros unicornis''), also called the Indian rhino, greater one-horned rhinoceros or great Indian rhinoceros, is a rhinoceros species native to the Indian subcontinent. It is listed as Vulnerable on the IUCN Red Li ...
,
Javan rhinoceros
The Javan rhinoceros (''Rhinoceros sondaicus''), also known as the Javan rhino, Sunda rhinoceros or lesser one-horned rhinoceros, is a very rare member of the family Rhinocerotidae and one of five extant rhinoceroses. It belongs to the same ge ...
,
Malayan tapir
The Malayan tapir (''Tapirus indicus''), also called Asian tapir, Asiatic tapir and Indian tapir, is the only tapir species native to Southeast Asia from the Malay Peninsula to Sumatra. It has been listed as Endangered on the IUCN Red List since ...
,
orangutan
Orangutans are great apes native to the rainforests of Indonesia and Malaysia. They are now found only in parts of Borneo and Sumatra, but during the Pleistocene they ranged throughout Southeast Asia and South China. Classified in the genu ...
s, and
gibbons.
Indomalaya has three endemic bird families, the Irenidae (
fairy bluebirds),
Megalaimidae
The Asian barbets are a family of bird species, the Megalaimidae, comprising two genera with 35 species native to the forests of the Indomalayan realm from Tibet to Indonesia. They were once clubbed with all barbets in the family Capitonidae bu ...
and Rhabdornithidae (
Philippine creepers). Also characteristic are
pheasant
Pheasants ( ) are birds of several genera within the family Phasianidae in the order Galliformes. Although they can be found all over the world in introduced (and captive) populations, the pheasant genera native range is restricted to Eurasia ...
s,
pittas
Pittas are a family, Pittidae, of passerine birds found in Asia, Australasia and Africa. There are thought to be 40 to 42 species of pittas, all similar in general appearance and habits. The pittas are Old World suboscines, and their closest re ...
,
Old World babbler
The Old World babblers or Timaliidae are a family of mostly Old World passerine birds. They are rather diverse in size and coloration, but are characterised by soft fluffy plumage. These are birds of tropical areas, with the greatest variety in S ...
s, and
flowerpecker
The flowerpeckers are a family, Dicaeidae, of passerine birds. The family comprises two genera, '' Prionochilus'' and '' Dicaeum'', with 50 species in total. The family has sometimes been included in an enlarged sunbird family Nectariniidae. The ...
s.
Indomalaya has 1000 species of
amphibians in 81 genera, about 17 of global species. 800 Indomalayan species, or 80%, are endemic. Indomalaya has three endemic families of amphibians,
Nasikabatrachidae,
Ichthyophiidae
The Ichthyophiidae are the family of Asiatic tailed caecilians or fish caecilians found in South and Southeast Asia as well as southernmost China.
They are primitive caecilians, lacking many of the derived characters found in the other families ...
, and
Uraeotyphlidae
''Uraeotyphlus'' is a genus of caecilians in the family Ichthyophiidae. There are seven species in this genus, all of which are endemic to the Western Ghats of southwestern India. Previously, the genus has also been placed in its own monotypi ...
. 329, or 33%, of Indomalayan amphibians are considered threatened or extinct, with habitat loss as the principal cause.
[Bain, R.H., Biju, S.D., Brown, R.M., Das, I., Diesmos, A.C., Dutta, S.K., Gower, D.J., Inger, R.F., Iskandar, D.T., Kaneko, Y., Neng, M.W., Lau, Meegaskumbura, M., Ohler, A., Papenfuss, T., Pethiyagoda, R., Stuart, B.L., & Wilkinson, M. (2008). ''Amphibians of the Indomalayan Realm'']
/ref>
More information is available under :Indomalayan realm fauna, Indomalayan realm fauna.
See also
* Ecoregions of India
Ecoregions of the world, spanning all land area (terrestrial) of the planet, were first defined and mapped in 2001 and subsequently revised in 2017. Later, freshwater ecoregions and Marine ecoregion, marine ecoregions of the world were identified. ...
* Ecoregions of the Philippines
The Philippine archipelago is one of the world's great reservoirs of biodiversity and endemism. The archipelago includes over 7000 islands, and a total land area of 300,780 km².
The Philippines was never connected to mainland Asia via land ...
* Mainland Southeast Asia (the Indochinese Peninsula)
* Malesia
Malesia is a biogeographical region straddling the Equator and the boundaries of the Indomalayan and Australasian realms, and also a phytogeographical floristic region in the Paleotropical Kingdom. It has been given different definitions. Th ...
* Sundaland
Indomalayan ecoregions
Bibliography
* Wikramanayake, E., E. Dinerstein, C. J. Loucks, D. M. Olson, J. Morrison, J. L. Lamoreux, M. McKnight, and P. Hedao. 2002. ''Terrestrial ecoregions of the Indo-Pacific: a conservation assessment''. Island Press, Washington, DC, USA
References
{{coord, 7, 00, N, 97, 00, E, source:kolossus-cawiki, display=title
Indomalayan realm,
Biogeographic realms
Biogeography
.
Environment of Asia
*
Natural history of Asia
Phytogeography