Biogeographic Realm
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A biogeographic realm or ecozone is the broadest
biogeographic Biogeography is the study of the distribution of species and ecosystems in geographic space and through geological time. Organisms and biological communities often vary in a regular fashion along geographic gradients of latitude, elevation, ...
division of Earth's land surface, based on distributional patterns of
terrestrial Terrestrial refers to things related to land or the planet Earth. Terrestrial may also refer to: * Terrestrial animal, an animal that lives on land opposed to living in water, or sometimes an animal that lives on or near the ground, as opposed to ...
organisms. They are subdivided into
bioregion A bioregion is an ecologically and geographically defined area that is smaller than a biogeographic realm, but larger than an ecoregion or an ecosystem, in the World Wide Fund for Nature classification scheme. There is also an attempt to use the ...
s, which are further subdivided into
ecoregion An ecoregion (ecological region) or ecozone (ecological zone) is an ecologically and geographically defined area that is smaller than a bioregion, which in turn is smaller than a biogeographic realm. Ecoregions cover relatively large areas of l ...
s.


Description

The realms delineate large areas of Earth's surface within which organisms have evolved in relative isolation over long periods of time, separated geographic features, such as
ocean The ocean (also the sea or the world ocean) is the body of salt water that covers approximately 70.8% of the surface of Earth and contains 97% of Earth's water. An ocean can also refer to any of the large bodies of water into which the wo ...
s, broad
desert A desert is a barren area of landscape where little precipitation occurs and, consequently, living conditions are hostile for plant and animal life. The lack of vegetation exposes the unprotected surface of the ground to denudation. About on ...
s, or high
mountain range A mountain range or hill range is a series of mountains or hills arranged in a line and connected by high ground. A mountain system or mountain belt is a group of mountain ranges with similarity in form, structure, and alignment that have arise ...
s, that constitute natural barriers to migration. As such, biogeographic realm designations are used to indicate general groupings of organisms based on their shared biogeography. Biogeographic realms correspond to the floristic kingdoms of
botany Botany, also called , plant biology or phytology, is the science of plant life and a branch of biology. A botanist, plant scientist or phytologist is a scientist who specialises in this field. The term "botany" comes from the Ancient Greek w ...
or zoogeographic regions of
zoology Zoology ()The pronunciation of zoology as is usually regarded as nonstandard, though it is not uncommon. is the branch of biology that studies the Animal, animal kingdom, including the anatomy, structure, embryology, evolution, Biological clas ...
. From 1872, Alfred Russel Wallace developed a system of zoogeographic regions, extending the ornithologist
Philip Sclater Philip Lutley Sclater (4 November 1829 – 27 June 1913) was an England, English lawyer and zoologist. In zoology, he was an expert ornithologist, and identified the main zoogeographic regions of the world. He was Secretary of the Zoological ...
's system of six regions. Biogeographic realms are characterized by the evolutionary history of the organisms they contain. They are distinct from
biome A biome () is a biogeographical unit consisting of a biological community that has formed in response to the physical environment in which they are found and a shared regional climate. Biomes may span more than one continent. Biome is a broader ...
s, also known as major habitat types, which are divisions of the Earth's surface based on ''life form'', or the adaptation of animals, fungi, micro-organisms and plants to climatic,
soil Soil, also commonly referred to as earth or dirt, is a mixture of organic matter, minerals, gases, liquids, and organisms that together support life. Some scientific definitions distinguish ''dirt'' from ''soil'' by restricting the former te ...
, and other conditions. Biomes are characterized by similar
climax vegetation In scientific ecology, climax community or climatic climax community is a historic term for a community of plants, animals, and fungi which, through the process of ecological succession in the development of vegetation in an area over time, hav ...
. Each realm may include a number of different biomes. A tropical moist broadleaf forest in Central America, for example, may be similar to one in New Guinea in its vegetation type and structure, climate, soils, etc., but these forests are inhabited by animals, fungi, micro-organisms and plants with very different evolutionary histories. The distribution of organisms among the world's biogeographic realms has been influenced by the distribution of
landmass A landmass, or land mass, is a large region or area of land. The term is often used to refer to lands surrounded by an ocean or sea, such as a continent or a large island. In the field of geology, a landmass is a defined section of continenta ...
es, as shaped by
plate tectonics Plate tectonics (from the la, label=Late Latin, tectonicus, from the grc, τεκτονικός, lit=pertaining to building) is the generally accepted scientific theory that considers the Earth's lithosphere to comprise a number of large ...
over the
geological history of the Earth Geology () is a branch of natural science concerned with Earth and other astronomical objects, the features or rocks of which it is composed, and the processes by which they change over time. Modern geology significantly overlaps all other Ea ...
.


Concept history

The "biogeographic realms" of Udvardy were defined based on taxonomic composition. The rank corresponds more or less to the
floristic kingdom A phytochorion, in phytogeography, is a geographic area with a relatively uniform composition of plant species. Adjacent phytochoria do not usually have a sharp boundary, but rather a soft one, a transitional area in which many species from both re ...
s and
zoogeographic region Zoogeography is the branch of the science of biogeography that is concerned with geographic distribution (present and past) of animal species. As a multifaceted field of study, zoogeography incorporates methods of molecular biology, genetics, mor ...
s. The usage of the term "ecozone" is more variable. It was used originally in stratigraphy (Vella 1962, Hedberg 1971). In Canadian literature, the term was used by Wiken in macro level
land classification Regionalisation is the tendency to form decentralised regions. Regionalisation or land classification can be observed in various disciplines: *In agriculture, see Agricultural Land Classification. *In biogeography, see Biogeography#Biogeographi ...
, with geographic criteria (see
Ecozones of Canada Canada has 20 major ecosystems -- ecozones, comprising 15 terrestrial units and 5 marine units. These ecozones are further subdivided into 53 ecoprovinces, 194 ecoregions, and 1,027 ecodistricts. These form the country's ecological land classif ...
). Later, Schültz would use it with ecological and physiognomical criteria, in a way similar to the concept of
biome A biome () is a biogeographical unit consisting of a biological community that has formed in response to the physical environment in which they are found and a shared regional climate. Biomes may span more than one continent. Biome is a broader ...
. In the
Global 200 The Global 200 is the list of ecoregions identified by the World Wide Fund for Nature ( WWF), the global conservation organization, as priorities for conservation. According to WWF, an ecoregion is defined as a "relatively large unit of land or w ...
/WWF scheme, originally the term "biogeographic realm" in Udvardy sense was used. However, in a scheme of
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...
, it was replaced by the term "ecozone".


Terrestrial biogeographic realms


Udvardy biogeographic realms


WWF / Global 200 biogeographic realms

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 ...
scheme is broadly similar to
Miklos Udvardy Miklos Dezso Ferenc Udvardy (March 23, 1919 – January 27, 1998) was a Hungarian-American biologist and university instructor. He contributed to a wide variety of disciplines, such as biogeography, evolutionary biology, ornithology, and veget ...
's system, the chief difference being the delineation of the Australasian realm relative to the Antarctic, Oceanic, and Indomalayan realms. In the WWF system, the Australasia realm includes
Australia Australia, officially the Commonwealth of Australia, is a Sovereign state, sovereign country comprising the mainland of the Australia (continent), Australian continent, the island of Tasmania, and numerous List of islands of Australia, sma ...
,
Tasmania ) , nickname = , image_map = Tasmania in Australia.svg , map_caption = Location of Tasmania in AustraliaCoordinates: , subdivision_type = Country , subdi ...
, 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 ...
,
New Guinea New Guinea (; Hiri Motu Hiri Motu, also known as Police Motu, Pidgin Motu, or just Hiri, is a language of Papua New Guinea, which is spoken in surrounding areas of Port Moresby (Capital of Papua New Guinea). It is a simplified version of ...
, the East Melanesian Islands,
New Caledonia ) , anthem = "" , image_map = New Caledonia on the globe (small islands magnified) (Polynesia centered).svg , map_alt = Location of New Caledonia , map_caption = Location of New Caledonia , mapsize = 290px , subdivision_type = Sovereign st ...
, and
New Zealand New Zealand ( mi, Aotearoa ) is an island country in the southwestern Pacific Ocean. It consists of two main landmasses—the North Island () and the South Island ()—and over 700 smaller islands. It is the sixth-largest island count ...
. Udvardy's Australian realm includes only Australia and Tasmania; he places
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 ...
in the Indomalayan Realm, New Guinea, New Caledonia, and East Melanesia in the Oceanian Realm, and New Zealand in the Antarctic Realm. The
Palearctic The Palearctic or Palaearctic is the largest of the eight biogeographic realms of the Earth. It stretches across all of Eurasia north of the foothills of the Himalayas, and North Africa. The realm consists of several bioregions: the Euro-Sibe ...
and
Nearctic The Nearctic realm is one of the eight biogeographic realms constituting the Earth's land surface. The Nearctic realm covers most of North America, including Greenland, Central Florida, and the highlands of Mexico. The parts of North America ...
are sometimes grouped into the
Holarctic realm The Holarctic realm is a biogeographic realm that comprises the majority of habitats found throughout the continents in the Northern Hemisphere. It corresponds to the floristic Boreal Kingdom. It includes both the Nearctic zoogeographical regio ...
.


Morrone biogeographic kingdoms

Following the nomenclatural conventions set out in the
International Code of Area Nomenclature The International Code of Area Nomenclature (ICAN) was proposed by a group of few biogeographers to provide a universal naming system or nomenclature for areas of endemism used in contemporary biogeography. There are other proposals to palaeobiogeog ...
, Morrone defined the next biogeographic kingdoms (or realms) and regions: * Holarctic kingdom Heilprin (1887) ** Nearctic region Sclater (1858) ** Palearctic region Sclater (1858) * Holotropical kingdom Rapoport (1968) ** Neotropical region Sclater (1858) ** Ethiopian region Sclater (1858) ** Oriental region Wallace (1876) * Austral kingdom Engler (1899) ** Cape region Grisebach (1872) ** Andean region Engler (1882) ** Australian region Sclater (1858) ** Antarctic region Grisebach (1872) * Transition zones: ** Mexican transition zone (Nearctic–Neotropical transition) ** Saharo-Arabian transition zone (Palearctic–Ethiopian transition) ** Chinese transition zone (Palearctic–Oriental transition zone transition) ** Indo-Malayan, Indonesian or Wallace's transition zone (Oriental–Australian transition) ** South American transition zone (Neotropical–Austral transition)


Freshwater biogeographic realms

The applicability of Udvardy scheme to most freshwater taxa is unresolved. The drainage basins of the principal oceans and seas of the world are marked by continental divides. The grey areas are
endorheic basin An endorheic basin (; also spelled endoreic basin or endorreic basin) is a drainage basin that normally retains water and allows no outflow to other external bodies of water, such as rivers or oceans, but drainage converges instead into lakes ...
s that do not drain to the ocean.


Marine biogeographic realms

According to Briggs and Morrone: According to the WWF scheme:


See also

*
Biome A biome () is a biogeographical unit consisting of a biological community that has formed in response to the physical environment in which they are found and a shared regional climate. Biomes may span more than one continent. Biome is a broader ...
* Cosmopolitan distribution *
Ecotone An ecotone is a transition area between two biological communities, where two communities meet and integrate. It may be narrow or wide, and it may be local (the zone between a field and forest) or regional (the transition between forest and gras ...
*
Phytochorion A phytochorion, in phytogeography, is a geographic area with a relatively uniform composition of plant species. Adjacent phytochoria do not usually have a sharp boundary, but rather a soft one, a transitional area in which many species from both re ...
and
World Geographical Scheme for Recording Plant Distributions The World Geographical Scheme for Recording Plant Distributions (WGSRPD) is a biogeographical system developed by the international Biodiversity Information Standards (TDWG) organization, formerly the International Working Group on Taxonomic Da ...
, used in botany


References

{{Biomes Biogeography Habitat