The Nearctic 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. ...
s constituting the Earth's land surface.
The Nearctic realm covers most of
North America
North America is a continent in the Northern Hemisphere and almost entirely within the Western Hemisphere. It is bordered to the north by the Arctic Ocean, to the east by the Atlantic Ocean, to the southeast by South America and th ...
, including
Greenland
Greenland ( kl, Kalaallit Nunaat, ; da, Grønland, ) is an island country in North America that is part of the Kingdom of Denmark. It is located between the Arctic and Atlantic oceans, east of the Canadian Arctic Archipelago. Greenland ...
,
Central Florida
Central Florida is a region of the U.S. state of Florida. Different sources give different definitions for the region, but as its name implies it is usually said to comprise the central part of the state, including the Tampa Bay area and the ...
, and the highlands of
Mexico
Mexico (Spanish language, Spanish: México), officially the United Mexican States, is a List of sovereign states, country in the southern portion of North America. It is borders of Mexico, bordered to the north by the United States; to the so ...
. The parts of North America that are not in the Nearctic realm are Eastern Mexico,
Southern Florida
South Florida is the southernmost region of the U.S. state of Florida. It is one of Florida's three most commonly referred to directional regions; the other two are Central Florida and North Florida. South Florida is the southernmost part of ...
, coastal
Central Florida
Central Florida is a region of the U.S. state of Florida. Different sources give different definitions for the region, but as its name implies it is usually said to comprise the central part of the state, including the Tampa Bay area and the ...
,
Central America
Central America ( es, América Central or ) is a subregion of the Americas. Its boundaries are defined as bordering the United States to the north, Colombia to the south, the Caribbean Sea to the east, and the Pacific Ocean to the west. ...
, and the
Caribbean
The Caribbean (, ) ( es, El Caribe; french: la Caraïbe; ht, Karayib; nl, De Caraïben) is a region of the Americas that consists of the Caribbean Sea, its islands (some surrounded by the Caribbean Sea and some bordering both the Caribbean ...
islands, which, together with
South America
South America is a continent entirely in the Western Hemisphere and mostly in the Southern Hemisphere, with a relatively small portion in the Northern Hemisphere at the northern tip of the continent. It can also be described as the sou ...
, are part of the
Neotropical realm
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.
Definition
In bioge ...
.
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 W ...
(WWF) divides the Nearctic into four
bioregions
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 th ...
, 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
The Aleutian Islands (; ; ale, Unangam Tanangin,”Land of the Aleuts", possibly from Chukchi ''aliat'', "island"), also called the Aleut Islands or Aleutic Islands and known before 1867 as the Catherine Archipelago, are a chain of 14 large v ...
to
Newfoundland
Newfoundland and Labrador (; french: Terre-Neuve-et-Labrador; frequently abbreviated as NL) is the easternmost province of Canada, in the country's Atlantic region. The province comprises the island of Newfoundland and the continental region ...
. It includes the Nearctic's
Arctic Tundra and
Boreal forest
Taiga (; rus, тайга́, p=tɐjˈɡa; relates to Mongolic and Turkic languages), generally referred to in North America as a boreal forest or snow forest, is a biome characterized by coniferous forests consisting mostly of pines, spruc ...
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
The Great Plains (french: Grandes Plaines), sometimes simply "the Plains", is a broad expanse of flatland in North America. It is located west of the Mississippi River and east of the Rocky Mountains, much of it covered in prairie, steppe, a ...
temperate grasslands of the Central United States and south-central Canada, the
temperate coniferous forests of the Southeastern United States, including
Central Florida
Central Florida is a region of the U.S. state of Florida. Different sources give different definitions for the region, but as its name implies it is usually said to comprise the central part of the state, including the Tampa Bay area and the ...
. 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
The Rocky Mountains, also known as the Rockies, are a major mountain range and the largest mountain system in North America. The Rocky Mountains stretch in straight-line distance from the northernmost part of western Canada, to New Mexico ...
(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
The Western United States (also called the American West, the Far West, and the West) is the region comprising the westernmost states of the United States. As American settlement in the U.S. expanded westward, the meaning of the term ''the We ...
.
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
California is a state in the Western United States, located along the Pacific Coast. With nearly 39.2million residents across a total area of approximately , it is the most populous U.S. state and the 3rd largest by area. It is also the m ...
, and the
Southwestern United States, including the
Chihuahuan,
Sonoran, and
Mojave Deserts. The
Mediterranean climate
A Mediterranean climate (also called a dry summer temperate climate ''Cs'') is a temperate climate sub-type, generally characterized by warm, dry summers and mild, fairly wet winters; these weather conditions are typically experienced in the ...
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 ...
s of the
Southern
Southern may refer to:
Businesses
* China Southern Airlines, airline based in Guangzhou, China
* Southern Airways, defunct US airline
* Southern Air, air cargo transportation company based in Norwalk, Connecticut, US
* Southern Airways Express, M ...
and
Central Coast of California
The Central Coast is an area of California, roughly spanning the coastal region between Point Mugu and Monterey Bay. It lies northwest of Los Angeles County and south of San Mateo and Santa Clara counties, and includes the rugged, undevelop ...
include the
California chaparral and woodlands
The California chaparral and woodlands is a terrestrial ecoregion of southwestern Oregon, northern, central, and southern California (United States) and northwestern Baja California (Mexico), located on the west coast of North America. It is a ...
,
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
The Sierra Madre Occidental is a major mountain range system of the North American Cordillera, that runs northwest–southeast through northwestern and western Mexico, and along the Gulf of California. The Sierra Madre is part of the American ...
,
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
The Madrean Region (named after the Sierra Madre Occidental) is a floristic region within the Holarctic Kingdom in North America, as delineated by Armen Takhtajan and Robert F. Thorne. It occupies arid or semiarid areas in the southwestern Unite ...
.
History
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
Eurasia (, ) is the largest continental area on Earth, comprising all of Europe and Asia. Primarily in the Northern and Eastern Hemispheres, it spans from the British Isles and the Iberian Peninsula in the west to the Japanese archipelag ...
as part of the supercontinent of
Laurasia, while South America was part of the supercontinent of
Gondwana
Gondwana () was a large landmass, often referred to as a supercontinent, that formed during the late Neoproterozoic (about 550 million years ago) and began to break up during the Jurassic period (about 180 million years ago). The final sta ...
. North America later split from Eurasia. North America has been joined by land bridges to both
Asia
Asia (, ) is one of the world's most notable geographical regions, which is either considered a continent in its own right or a subcontinent of Eurasia, which shares the continental landmass of Afro-Eurasia with Africa. Asia covers an are ...
and South America since then, which allowed an exchange of plant and animal
species
In biology, a species is the basic unit of classification and a taxonomic rank of an organism, as well as a unit of biodiversity. A species is often defined as the largest group of organisms in which any two individuals of the appropriat ...
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 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-Sib ...
. The two realms are sometimes included in a single
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 regi ...
.
Many large animals, or
megafauna, including
horse
The horse (''Equus ferus caballus'') is a domesticated, one-toed, hoofed mammal. It belongs to the taxonomic family Equidae and is one of two extant subspecies of ''Equus ferus''. The horse has evolved over the past 45 to 55 million yea ...
s,
camel
A camel (from: la, camelus and grc-gre, κάμηλος (''kamēlos'') from Hebrew or Phoenician: גָמָל ''gāmāl''.) is an even-toed ungulate in the genus ''Camelus'' that bears distinctive fatty deposits known as "humps" on its back. ...
s,
mammoth
A mammoth is any species of the extinct elephantid genus ''Mammuthus'', one of the many genera that make up the order of trunked mammals called proboscideans. The various species of mammoth were commonly equipped with long, curved tusks an ...
s,
mastodon
A mastodon ( 'breast' + 'tooth') is any proboscidean belonging to the extinct genus ''Mammut'' (family Mammutidae). Mastodons inhabited North and Central America during the late Miocene or late Pliocene up to their extinction at the end of the ...
ts,
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
The Pleistocene ( , often referred to as the ''Ice age'') is the geological Epoch (geology), epoch that lasted from about 2,580,000 to 11,700 years ago, spanning the Earth's most recent period of repeated glaciations. Before a change was fina ...
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
The American bison (''Bison bison'') is a species of bison native to North America. Sometimes colloquially referred to as American buffalo or simply buffalo (a different clade of bovine), it is one of two extant species of bison, alongside the ...
(''Bison bison''),
brown bear
The brown bear (''Ursus arctos'') is a large bear species found across Eurasia and North America. In North America, the populations of brown bears are called grizzly bears, while the subspecies that inhabits the Kodiak Islands of Alaska is k ...
or grizzly bear (''Ursus arctos''),
moose
The moose (in North America) or elk (in Eurasia) (''Alces alces'') is a member of the New World deer subfamily and is the only species in the genus ''Alces''. It is the largest and heaviest extant species in the deer family. Most adult ma ...
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
Mammals originally unique to the Nearctic include:
*Order
Primates- the first primate/proto-primate, ''
Purgatorius'', originated in the
Early Paleocene
The Danian is the oldest age or lowest stage of the Paleocene Epoch or Series, of the Paleogene Period or System, and of the Cenozoic Era or Erathem. The beginning of the Danian (and the end of the preceding Maastrichtian) is at the Cretaceous� ...
of the Nearctic.
*Family
Canidae-
dogs,
wolves,
foxes, and
coyotes.
*Family
Camelidae
Camelids are members of the biological family Camelidae, the only currently living family in the suborder Tylopoda. The seven extant members of this group are: dromedary camels, Bactrian camels, wild Bactrian camels, llamas, alpacas, vicuñas ...
-
camel
A camel (from: la, camelus and grc-gre, κάμηλος (''kamēlos'') from Hebrew or Phoenician: גָמָל ''gāmāl''.) is an even-toed ungulate in the genus ''Camelus'' that bears distinctive fatty deposits known as "humps" on its back. ...
s and their South American relatives including the
llama. Now extinct in the Nearctic
*Family
Equidae-
horse
The horse (''Equus ferus caballus'') is a domesticated, one-toed, hoofed mammal. It belongs to the taxonomic family Equidae and is one of two extant subspecies of ''Equus ferus''. The horse has evolved over the past 45 to 55 million yea ...
s,
donkeys and their relatives. Now only found in the Nearctic as feral horses.
*Family
Tapiridae-
tapir
Tapirs ( ) are large, herbivorous mammals belonging to the family Tapiridae. They are similar in shape to a pig, with a short, prehensile nose trunk. Tapirs inhabit jungle and forest regions of South and Central America, with one species inh ...
s now extinct in the Nearctic.
*Family
Antilocapridae
The Antilocapridae are a family of artiodactyls endemic to North America. Their closest extant relatives are the giraffids with which they comprise the superfamily Giraffoidea. Only one species, the pronghorn (''Antilocapra americana''), is ...
- last survivor of which is the
pronghorn.
*Subfamily
Tremarctinae, or the short-faced
bears- including the giant short-faced bear (''
Arctodus simus''). One other member of the group is the
spectacled bear (''Tremarctos ornatus'') of South America.
Flora and fauna endemic to the Nearctic
One
bird
Birds are a group of warm-blooded vertebrates constituting the class Aves (), characterised by feathers, toothless beaked jaws, the laying of hard-shelled eggs, a high metabolic rate, a four-chambered heart, and a strong yet lightweig ...
family, the
wrentits (Timaliinae), is endemic to the Nearctic region. The Holarctic has four endemic families:
divers (Gaviidae),
grouse (Tetraoninae),
auk
An auk or alcid is a bird of the family Alcidae in the order Charadriiformes. The alcid family includes the murres, guillemots, auklets, puffins, and murrelets. The word "auk" is derived from Icelandic ''álka'', from Old Norse ''alka'' (a ...
s (Alcidae), and the
waxwing
The waxwings are three species of passerine birds classified in the genus ''Bombycilla''. They are pinkish-brown and pale grey with distinctive smooth plumage in which many body feathers are not individually visible, a black and white eyestri ...
s (Bombycillidae). The scarab beetle families
Pleocomidae and
Diphyllostomatidae
The false stag beetles (''Diphyllostoma'') are a group of three species of rare beetles known only from California. Almost nothing is known of their life history beyond that the adults are diurnal and females are flightless; larvae have not bee ...
(
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
The Limnanthaceae are a small family of annual herbs occurring throughout temperate North America. There are eight species and nineteen taxa currently recognized. Members of this family are prominent in vernal pool communities of California. Some ...
.
Nearctic terrestrial ecoregions
See also
*
List of ecoregions in Canada (WWF)
*
List of ecoregions in Mexico (WWF)
*
List of ecoregions in the United States (WWF)
The following is a list of ecoregions in the United States as identified by the World Wide Fund for Nature (WWF). The United States is a megadiverse country with a high level of endemism across a wide variety of ecosystems.
Terrestrial ecoregi ...
References
* Abell, R.A. et al. (2000). ''Freshwater Ecoregions of North America: A Conservation Assessment'' Washington, DC: Island Press
* 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.
External links
*
Map of the ecozonesNearctica, The Natural World of North America*
{{Authority control
Nearctic realm,
Biogeographic realms