Biogeographic realm in the context of Neotropic

The Palearctic or Palaearctic is a biogeographic realm of the Earth, the largest of eight. Confined almost entirely to the Eastern Hemisphere, it stretches across Europe and Asia, north of the foothills of the Himalayas, and North Africa.

The realm consists of several bioregions: the Mediterranean Basin; North Africa; North Arabia; Western, Central, South and East Asia. The Palaearctic realm also has numerous rivers and lakes, forming several freshwater ecoregions.

Ecoregions (ecological regions) are ecological and geographic areas that exist on multiple different levels, defined by type, quality, and quantity of environmental resources. Ecoregions cover relatively large areas of land or water, and contain characteristic, geographically distinct assemblages of natural communities and species. The biodiversity of flora, fauna and ecosystems that characterise an ecoregion tends to be distinct from that of other ecoregions. In theory, biodiversity or conservation ecoregions are relatively large areas of land or water where the probability of encountering different species and communities at any given point remains relatively constant, within an acceptable range of variation (largely undefined at this point).Ecoregions are also known as "ecozones" ("ecological zones"), although that term may also refer to biogeographic realms.

Three caveats are appropriate for all bio-geographic mapping approaches. Firstly, no single bio-geographic framework is optimal for all taxa. Ecoregions reflect the best compromise for as many taxa as possible. Secondly, ecoregion boundaries rarely form abrupt edges; rather, ecotones and mosaic habitats bound them. Thirdly, most ecoregions contain habitats that differ from their assigned biome. Biogeographic provinces may originate due to various barriers, including physical (plate tectonics, topographic highs), climatic (latitudinal variation, seasonal range) and ocean chemical related (salinity, oxygen levels).

The Great American Biotic Interchange (commonly abbreviated as GABI), also known as the Great American Interchange and the Great American Faunal Interchange, was an important late Cenozoic paleozoogeographic biotic interchange event in which land and freshwater fauna migrated from North America to South America via Central America and vice versa, as the volcanic Isthmus of Panama rose up from the sea floor, forming a land bridge between the previously separated continents. Although earlier dispersals had occurred, probably over water, the migration accelerated dramatically about 2.7 million years (Ma) ago during the Piacenzian age. It resulted from the joining of the Neotropic (roughly South American) and Nearctic (roughly North American) biogeographic realms definitively to form the Americas. The interchange is visible from observation of both biostratigraphy and nature (neontology). Its most dramatic effect is on the zoogeography of mammals, but it also gave an opportunity for reptiles, amphibians, arthropods, weak-flying or flightless birds, and even freshwater fish to migrate. Coastal and marine biota were affected in the opposite manner; the formation of the Central American Isthmus caused what has been termed the Great American Schism, with significant diversification and extinction occurring as a result of the isolation of the Caribbean from the Pacific.

The occurrence of the interchange was first discussed in 1876 by the "father of biogeography", Alfred Russel Wallace. Wallace had spent five years exploring and collecting specimens in the Amazon basin. Others who made significant contributions to understanding the event in the century that followed include Florentino Ameghino, W. D. Matthew, W. B. Scott, Bryan Patterson, George Gaylord Simpson and S. David Webb. The Pliocene timing of the formation of the connection between North and South America was discussed in 1910 by Henry Fairfield Osborn.

The Neotropical realm is one of the eight biogeographic realms constituting Earth's land surface. Physically, it includes the tropical terrestrial ecoregions of the Americas and the entire South American temperate zone.

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 the English biologist Thomas Henry Huxley.

It separates the biogeographic realms of Asia and 'Wallacea', a transitional zone between Asia and Australia formerly also called the Malay Archipelago and the Indo-Australian Archipelago (present day Indonesia). To the west of the line are found organisms related to Asiatic species; to the east, a mixture of species of Asian and Australian origins is present. Wallace noticed this clear division in both land mammals and birds during his travels through the East Indies in the 19th century.

The Australasian realm is one of eight biogeographic realms that is coincident with, but not (by some definitions) the same as, the geographical region of Australasia. The realm includes Australia, the island of New Guinea (comprising Papua New Guinea and the Indonesian province of Papua), and the eastern part of the Indonesian archipelago, including the island of Sulawesi, the Moluccas (the Indonesian provinces of Maluku and North Maluku), and the islands of Lombok, Sumbawa, Sumba, Flores, and Timor, often known as the Lesser Sundas.

The Australasian realm also includes several Pacific island groups, including the Bismarck Archipelago, Vanuatu, the Solomon Islands, and New Caledonia. New Zealand and its surrounding islands are a distinctive sub-region of the Australasian realm. The rest of Indonesia is part of the Indomalayan realm. In the classification scheme developed by Miklos Udvardy, New Guinea, New Caledonia, Solomon Islands and New Zealand are placed in the Oceanian realm.

The Oceanian realm is one of the eight biogeographic realms and is unique in not including any continental land mass. It has the smallest land area of any of the WWF realms.

This realm includes the islands of the Pacific Ocean in Micronesia, the Fijian Islands, the Hawaiian Islands, and Polynesia (with the exception of New Zealand). New Zealand, Australia, and most of Melanesia including New Guinea, Vanuatu, the Solomon Islands, and New Caledonia are included within the Australasian realm.

A bioregion is a geographical area defined not by administrative boundaries, but by distinct characteristics such as plant and animal species, ecological systems, soils and landforms, human settlements, and topographic features such as drainage basins (also referred to as "watersheds"). A bioregion can be on land or at sea. The idea of bioregions was adopted and popularized in the mid-1970s by a school of philosophy called bioregionalism, which includes the concept that human culture can influence bioregional definitions due to its effect on non-cultural factors. Bioregions are part of a nested series of ecological scales, generally starting with local watersheds, growing into larger river systems, then Level III or IV ecoregions (or regional ecosystems), bioregions, then biogeographical realm, followed by the continental-scale and ultimately the biosphere.

Within the life sciences, there are numerous methods used to define the physical limits of a bioregion based on the spatial extent of mapped ecological phenomena—from species distributions and hydrological systems (i.e. Watersheds) to topographic features (e.g. landforms) and climate zones (e.g. Köppen classification). Bioregions also provide an effective framework in the field of Environmental history, which seeks to use "river systems, ecozones, or mountain ranges as the basis for understanding the place of human history within a clearly delineated environmental context". A bioregion can also have a distinct cultural identity defined, for example, by Indigenous Peoples whose historical, mythological and biocultural connections to their lands and waters shape an understanding of place and territorial extent. Within the context of bioregionalism, bioregions can be socially constructed by modern-day communities for the purposes of better understanding a place "with the aim to live in that place sustainably and respectfully."

The Afrotropical realm is one of the Earth's eight biogeographic realms. It includes Sub-Saharan Africa, the southern Arabian Peninsula, the island of Madagascar, and the islands of the western Indian Ocean. It was formerly known as the Ethiopian Zone or Ethiopian Region.

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 that are not in the Nearctic realm include most of coastal Mexico, southern Mexico, southern Florida, coastal central Florida, Central America, Bermuda and the Caribbean islands. Together with South America, these regions are part of the Neotropical realm.

The Indomalayan realm is one of the eight biogeographic realms. It extends across most of South and Southeast Asia and into the southern parts of East Asia.

Also called the Oriental realm by biogeographers, Indomalaya spreads all over the Indian subcontinent and Southeast Asia to lowland southern China, and through Indonesia as far as Sumatra, Java, Bali, and Borneo, east of which lies the Wallace line, the realm boundary named after Alfred Russel Wallace which separates Indomalaya from Australasia. Indomalaya also includes the Philippines, lowland Taiwan, and Japan's Ryukyu Islands.

This page features a list of biogeographic provinces that were developed by Miklos Udvardy in 1975, later modified by other authors. Biogeographic Province is a biotic subdivision of biogeographic realms subdivided into ecoregions, which are classified based on their biomes or habitat types and, on this page, correspond to the floristic kingdoms of botany.

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