Nearctic realm

The Nearctic is one of the eight biogeographic realms constituting the Earth's land surface.

Ecozone Nearctic
The Nearctic realm

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 are Eastern Mexico, Southern Florida, coastal Central Florida, Central America, and the Caribbean islands which are part of the Neotropical realm, together with South America.

Major ecological regions

The World Wildlife Fund (WWF) divides the Nearctic into four bioregions, defined as "geographic clusters of ecoregions that may span several habitat types, but have strong biogeographic affinities, particularly at taxonomic levels higher than the species level (genus, family)."

Canadian Shield

The Canadian Shield bioregion extends across the northern portion of the continent, from the Aleutian Islands to Newfoundland. It includes the Nearctic's Arctic Tundra and Boreal forest ecoregions.

In terms of floristic provinces, it is represented by part of the Canadian Province of the Circumboreal Region.

Eastern North America

The Eastern North America bioregion includes the temperate broadleaf and mixed forests of the Eastern United States and southeastern Canada, the Great Plains temperate grasslands of the Central United States and south-central Canada, the temperate coniferous forests of the Southeastern United States, including Central Florida. In terms of floristic provinces, it is represented by the North American Atlantic Region and part of the Canadian Province of the Circumboreal Region.

Western North America

The Western North America bioregion includes the temperate coniferous forests of the coastal and mountain regions of southern Alaska, western Canada, and the Western United States from the Pacific Coast and Northern California to the Rocky Mountains (known as the Cascadian bioregion), as well as the cold-winter intermountain deserts and xeric shrublands and temperate grasslands and shrublands of the Western United States.

In terms of floristic provinces, it is represented by the Rocky Mountain region.

Northern Mexico and Southwestern North America

The Northern Mexico bioregion includes the mild-winter to cold-winter deserts and xeric shrublands of northern Mexico, Southern California, and the Southwestern United States, including the Chihuahuan, Sonoran, and Mojave Deserts. The Mediterranean climate ecoregions of the Southern and Central Coast of California include the California chaparral and woodlands, California coastal sage and chaparral, California interior chaparral and woodlands, and California montane chaparral and woodlands.

The bioregion also includes the warm temperate and subtropical pine and pine-oak forests, including the Arizona Mountains forests and the Sierra Madre Occidental, Sierra Madre Oriental, and Sierra Juarez and San Pedro Martir pine-oak forests.

In terms of floristic provinces, it is represented by the Madrean Region.


Although North America and South America are presently joined by the Isthmus of Panama, these continents were separated for about 180 million years, and evolved very different plant and animal lineages. When the ancient supercontinent of Pangaea split into two about 180 million years ago, North America remained joined to Eurasia as part of the supercontinent of Laurasia, while South America was part of the supercontinent of Gondwana. North America later split from Eurasia. North America has been joined by land bridges to both Asia and South America since then, which allowed an exchange of plant and animal species between the continents, the Great American Interchange.

A former land bridge across the Bering Strait between Asia and North America allowed many plants and animals to move between these continents, and the Nearctic realm shares many plants and animals with the Palearctic. The two realms are sometimes included in a single Holarctic realm.

Many large animals, or megafauna, including horses, camels, mammoths, mastodonts, ground sloths, sabre-tooth cats (Smilodon), the giant short-faced bear (Arctodus simus), and the cheetah, became extinct in North America at the end of the Pleistocene epoch (ice ages), at the same time the first evidence of humans appeared, in what is called the Holocene extinction event. Previously, the megafaunal extinctions were believed to have been caused by the changing climate, but many scientists now believe, while the climate change contributed to these extinctions, the primary cause was hunting by newly arrived humans or, in the case of some large predators, extinction resulting from prey becoming scarce. The American bison (Bison bison), brown bear or grizzly bear (Ursus arctos), moose or Eurasian elk (Alces alces), and elk or wapiti (Cervus canadensis) entered North America around the same time as the first humans, and expanded rapidly, filling ecological niches left empty by the newly extinct North American megafauna.

Flora and fauna

Flora and fauna that originated in the Nearctic

Animals originally unique to the Nearctic include:

Flora and fauna endemic to the Nearctic

One bird family, the wrentits (Timaliinae), is endemic to the Nearctic region. The Holarctic has four endemic families: divers (Gaviidae), grouse (Tetraoninae), auks (Alcidae), and the waxwings (Bombycillidae). The scarab beetle families Pleocomidae and Diphyllostomatidae (Coleoptera) are also endemic to the Nearctic. The fly species Cynomya cadaverina is also found in high numbers in this area.

Plants families endemic or nearly endemic to the Nearctic include the Crossosomataceae, Simmondsiaceae, and Limnanthaceae.

Nearctic terrestrial ecoregions

Sonoran-Sinaloan transition subtropical dry forest Mexico
Bermuda subtropical conifer forests Bermuda
Sierra Madre Occidental pine-oak forests Mexico, United States
Sierra Madre Oriental pine-oak forests Mexico, United States
Allegheny Highlands forests United States
Appalachian mixed mesophytic forests United States
Appalachian-Blue Ridge forests United States
California mixed evergreen forest United States
Central U.S. hardwood forests United States
East Central Texas forests United States
Eastern forest-boreal transition Canada, United States
Eastern Great Lakes lowland forests Canada, United States
Gulf of St. Lawrence lowland forests Canada
Lac Saint-Jean and Saguenay valley forests Canada
Middle Atlantic coastal forests Southeastern United States
Mississippi lowland forests United States
New England-Acadian forests Canada, United States
Northeastern coastal forests United States
Ozark Mountain forests United States
Southeastern mixed forests United States
Southeastern subtropical evergreen forests United States
Southern Great Lakes forests United States
Upper Midwest forest-savanna transition United States
Western Great Lakes forests Canada, United States
Willamette Valley forests United States
Nearctic temperate coniferous forests
Alberta Mountain forests Canada
Alberta-British Columbia foothills forests Canada
Arizona Mountains forests United States
Atlantic coastal pine barrens United States
Blue Mountains forests United States
British Columbia mainland coastal forests Canada, United States
Cascade Mountains leeward forests Canada, United States
Central and Southern Cascades forests United States
Central British Columbia Mountain forests Canada
Central Pacific coastal forests Canada, United States
Colorado Rockies forests United States
Eastern Cascades forests Canada, United States
Fraser Plateau and Basin complex Canada
Florida Scrub United States
Great Basin montane forests United States
Klamath-Siskiyou forests United States
Maritime Coast Range Ponderosa Pine forests United States
Middle Atlantic coastal forests United States
North Central Rockies forests Canada, United States
Northern California coastal forests United States
Northern Pacific coastal forests Canada, United States
Northern transitional alpine forests Canada
Okanogan dry forests Canada, United States
Piney Woods forests United States
Puget lowland forests Canada, United States
Haida Gwaii Canada
Sierra Nevada forests United States
South Central Rockies forests United States
Southeastern conifer forests United States
Wasatch and Uinta montane forests United States
Alaska Peninsula montane taiga United States
Central Canadian Shield forests Canada
Cook Inlet taiga United States
Copper Plateau taiga United States
Eastern Canadian forests Canada
Eastern Canadian Shield taiga Canada
Interior Alaska-Yukon lowland taiga Canada, United States
Mid-Continental Canadian forests Canada
Midwestern Canadian Shield forests Canada
Muskwa-Slave Lake forests Canada
Newfoundland Highland forests Canada
Northern Canadian Shield taiga Canada
Northern Cordillera forests Canada
Northwest Territories taiga Canada
South Avalon-Burin oceanic barrens Canada
Northern Lake Superior Taiga United States, Canada
Southern Hudson Bay taiga Canada
Yukon Interior dry forests Canada
Western Gulf coastal grasslands Mexico, United States
California Central Valley grasslands United States
Canadian aspen forests and parklands Canada, United States
Central and Southern mixed grasslands United States
Central forest-grasslands transition United States
Central tall grasslands United States
Columbia Plateau United States
Edwards Plateau savanna United States
Flint Hills tall grasslands United States
Montana valley and foothill grasslands United States
Nebraska Sand Hills mixed grasslands United States
Northern mixed grasslands Canada, United States
Northern short grasslands Canada, United States
Northern tall grasslands Canada, United States
Palouse grasslands United States
Texas blackland prairies United States
Western short grasslands United States
Alaska-St. Elias Range tundra Canada, United States
Aleutian Islands tundra United States
Arctic coastal tundra Canada, United States
Arctic foothills tundra Canada, United States
Baffin coastal tundra Canada
Beringia lowland tundra United States
Beringia upland tundra United States
Brooks-British Range tundra Canada, United States
Davis Highlands tundra Canada
High Arctic tundra Canada
Interior Yukon-Alaska alpine tundra Canada, United States
Kalaallit Nunaat high arctic tundra Greenland
Kalaallit Nunaat low arctic tundra Greenland
Low Arctic tundra Canada
Middle Arctic tundra Canada
Ogilvie-MacKenzie alpine tundra Canada, United States
Pacific Coastal Mountain icefields and tundra Canada, United States
Torngat Mountain tundra Canada
California coastal sage and chaparral Mexico, United States
California interior chaparral and woodlands United States
California montane chaparral and woodlands United States
Baja California desert Mexico
Central Mexican matorral Mexico
Chihuahuan desert Mexico, United States
Colorado Plateau shrublands United States
Great Basin shrub steppe United States
Gulf of California xeric scrub Mexico
Meseta Central matorral Mexico
Mojave desert United States
Okanagan (South) shrub steppe Canada
Snake-Columbia shrub steppe United States
Sonoran desert Mexico, United States
Tamaulipan matorral Mexico,
Tamaulipan mezquital Mexico, United States
Wyoming Basin shrub steppe United States


  • Abell, R.A. et al. (2000). Freshwater Ecoregions of North America: A Conservation Assessment Washington, DC: Island Press, [1].
  • Flannery, Tim (2001). The Eternal Frontier: an Ecological History of North America and its Peoples. Grove Press, New York.
  • Ricketts, Taylor H., Eric Dinerstein, David M. Olson, Colby J. Loucks, et al. (1999). Terrestrial Ecoregions of North America: a Conservation Assessment. Island Press, Washington DC., [2].

External links

  • Map of the ecozones
  • Nearctica, The Natural World of North America
  • Wikisource-logo.svg "Nearctic Region" . New International Encyclopedia. 1905.

Brachypnoea is a genus of leaf beetles in the subfamily Eumolpinae. It is mostly found in the Neotropical realm, though there are also eight known species in the Nearctic realm.The genus was originally named Noda, named by Chevrolat in Dejean's Catalogue in 1836. However, this was preoccupied by Noda Schellenberg, 1803, a genus in Diptera. Two replacement names were made for Noda: Brachypnoea, by Gistel in 1850 (1848?), and Nodonota by Édouard Lefèvre in 1885. Since Brachypnoea was published first, it has priority over Nodonota.

Brown bear

The brown bear (Ursus arctos) is a bear that is found across much of northern Eurasia and North America. In North America, the populations of brown bears are often called grizzly bears. It is one of the largest living terrestrial members of the order Carnivora, rivaled in size only by its closest relative, the polar bear (Ursus maritimus), which is much less variable in size and slightly larger on average.The brown bear's principal range includes parts of Russia, Central Asia, China, Canada, the United States, Scandinavia and the Carpathian region, especially Romania, Anatolia and the Caucasus, Bristol. The brown bear is recognized as a national and state animal in several European countries.While the brown bear's range has shrunk and it has faced local extinctions, it remains listed as a least concern species by the International Union for Conservation of Nature (IUCN) with a total population of approximately 200,000. As of 2012, this and the American black bear are the only bear species not classified as threatened by the IUCN. However, the California grizzly bear, Atlas bear and Mexican grizzly bear were hunted to extinction in the 19th and early 20th centuries and many of the southern Asian subspecies are highly endangered. One of the smaller-bodied subspecies, the Himalayan brown bear, is critically endangered, occupying only 2% of its former range and threatened by uncontrolled poaching for its body parts. The Marsican brown bear of central Italy is one of several currently isolated populations of the Eurasian brown bear, and believed to have a population of just 40 to 50 bears.


Calycopis is a genus of butterflies in the family Lycaenidae. Massively split up by Kurt Johnson in 1991, most modern authors consider the changes proposed at that time to be unjustified. Most of the species of this genus are found in the Neotropical realm and others in the Nearctic realm.

Species include:

Calycopis cecrops Fabricius, 1793 – red-banded hairstreak

Calycopis isobeon Butler & H. Druce, 1872

Calycopis pisis (Godman & Salvin, 1887)

Calycopis trebula (Hewitson, 1868); Trebula groundstreakSeveral proposed species are of doubtful validity.

Coenosia attenuata

Coenosia attenuata (also sometimes cited as Coenosia attenuate), commonly called "hunter fly" or It is well known under the name "killer fly", is a predatory fly belonging to the family Muscidae.


Cotalpa is a genus of beetle in the family Scarabaeidae. All six species within the genus are found in the Nearctic realm.

Eana osseana

Eana osseana, common name dotted shade, is a moth of the family Tortricidae.

Guianan mangroves

The Guianan mangroves (NT1411) is a coastal ecoregion of southeastern Venezuela, Guyana, Suriname and French Guiana.

The mangroves provide an important habitat for migrating birds that winter in the area.

Large areas are intact, although they are threatened by destruction of the trees for timber and to make way for agriculture, and from upstream agricultural and industrial pollution.


Hurleyella is a genus of flies in the family Dolichopodidae from the Nearctic and Neotropical realms. Subfamily placement of this genus is currently uncertain, though in some aspects the genus fits into Medeterinae. The genus is named after the late dipterist Richard Hurley.

List of biogeographic provinces

Biogeographic Province is a biotic subdivision of realms.

The following list of biogeographic provinces was developed by Miklos Udvardy in 1975, later modified by other authors.


Melasis is a genus of soldier beetles native to North America and parts of Europe. It contains fourteen species, four of which can be found in the Nearctic realm.

Neotropical realm

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

Nesoselandria morio

Nesoselandria morio is a species of sawflies belonging to the family Tenthredinidae subfamily Tenthrediniinae. It is the only species of the genus Nesoselandria.

Phyciodes cocyta

Phyciodes cocyta, the northern crescent, is a butterfly of the family Nymphalidae. It is found in the Nearctic realm.

The wingspan is 32–38 mm. The butterfly flies from June to July depending on the location.

The larvae feed on Asteraceae species.

Phyciodes pulchella

Phyciodes pulchella, the field crescent, is a butterfly of the family Nymphalidae. It is found in the Nearctic realm.

The wingspan is 24–36 mm. The butterfly flies from May to August in Canada.The larvae feed on Asteraceae species.


Phyllophaga is a very large genus (more than 900 species) of New World scarab beetles in the subfamily Melolonthinae. Common names for this genus and many other related genera in the subfamily Melolonthinae are May beetles, June bugs, and June beetles. They range in size from 12 to 35 mm (0.47 to 1.38 in) and are blackish or reddish-brown in colour, without prominent markings, and often rather hairy ventrally. These beetles are nocturnal, coming to lights in great numbers.

The generic name is derived from the Greek words phyllon (φυλλον), which means "leaf", and phagos (φαγος), which means "eater", with a plural ending.

Plagiognathus arbustorum

Plagiognathus arbustorum is a species of insects in the family Miridae, the plant bugs.

Río Verde (Oaxaca)

The Río Verde is a river in the state of Oaxaca in Mexico. It is formed by the confluence of the Atoyaquillo and Colorado Rivers near the village of Santiago Ixtayutla and flows south to its mouth at El Azufre on the Pacific Ocean, on the western border of Lagunas de Chacahua National Park. Its major tributary is the Atoyac, which drains the Oaxaca Valley and flows into the Río Verde at Paso de la Reina, where a proposal to build a large hydroelectric dam project has been opposed by local communities. The combined length of the Atoyac and lower Verde rivers is 342 kilometres (213 mi) and the river system as a whole drains a watershed of 18,812 square kilometres (7,263 sq mi), which has a mean natural surface runoff of 6,046 hm3 (2.135×1011 cu ft) per year. The watershed covers almost a fifth of Oaxaca state and is home to over a third of its population, and faces serious degradation issues as a result of pollution and overexploitation.Well-studied Mesoamerican civilizations flourished in the valleys of Oaxaca, Ejutla and Nochixtlán, all of which lie in the Verde–Atoyac basin. The floodplains of the lower Río Verde valley also began to support large populations and complex society in the Late Formative period (400–100 BC). The site of Río Viejo emerged as a regional centre during the Miniyua phase (150 BC–100 AD), developing massive public architecture by the Late Classic period (550–800 AD). In the Postclassic period development shifted away from the floodplains to the city-state of Tututepec, located in the foothills about 16 km east of Río Viejo.In the context of freshwater fish biogeography, the Verde–Atoyac basin is considered the southern extent of the Nearctic realm on the Pacific coast.


Scarabaeoidea is a superfamily of beetles, the only subgroup of the infraorder Scarabaeiformia. Around 35,000 species are placed in this superfamily and some 200 new species are described each year. Its constituent families are also undergoing revision presently, and the family list below is only preliminary.

Xanthochilus saturnius

Xanthochilus saturnius, the Mediterranean seed bug, is a species of true bugs belonging to the family Rhyparochromidae.Xanthochilus is sometimes considered a subgenus of Rhyparochromus, in which case this species is called Rhyparochromus saturnius or Rhyparochromus (Xanthochilus) saturnius.

See also


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