Sweet clover (Melilotus sp. This article is about the genus of grassland plants For the moshav see Mlilot. ), introduced and naturalized to the U. Naturalization is the acquisition of Citizenship or Nationality by somebody who was not a citizen or national of that country when he or she was born S. from Eurasia as a forage and cover crop.

An introduced species (also known as naturalized species or exotic species) is an organism that is not indigenous to a given location but instead has been accidentally or deliberately introduced to a new location by human activity or by natural means. In Ecology, an indigenous Species is an Organism which is native to a given region or Ecosystem. Human beings, humans or man (Origin 1590–1600 L homō man OL hemō the earthly one (see Humus Introduced species sometimes are damaging to the ecosystem they are introduced into, others negatively affect agriculture and other human uses of natural resources or impact on the health of animals and humans. A list of introduced species is given in a separate article. A complete List of introduced species for even quite small areas of the world would be dauntingly long Introduced species and their effects on natural environments is a controversial subject and one that has gained much scrutiny by scientists, governments, farmers and others.

Terminology

The terminology associated with introduced species is presently in flux for a variety of reasons. Other terms that are used sometimes interchangeably (having the same or similar meanings) with introduced are acclimatized, adventive, native, naturalized, immigrant, non-indigenous, and xenobiotic. Nonetheless, distinctions can and should be made between some of these terms.

In the broadest and most widely used sense, an introduced species is synonymous with non-native and therefore applies as well to most garden and farm organisms; these adequately fit the basic definition given above. However, some sources add to that basic definition: ". . . and are now reproducing in the wild",^[1] which removes from consideration as introduced all of those species raised or grown in gardens or farms that do not survive without tending by people. With respect to plants, these latter are in this case defined as either ornamental or cultivated plants.

The following definition from the United States Environmental Protection Agency, although perhaps lacking ecological sophistication, is more typical: introduced species are . . "[s]pecies that have become able to survive and reproduce outside the habitats where they evolved or spread naturally". ^[2] However, introduction of a species outside its native range is often all that is required to be qualified as an "introduced species" such that one can distinguish between introduced species that may only occur in cultivation, under domestication or captivity whereas other become established outside their native range and reproduce without human assistance. Such species might be termed "naturalized", "established", "wild non-native species", or "invasive". The transition from introduction, to establishment and invasion has been described by Richardson et al 2000 in the context of plants. Introduced species are essentially "non-native" species. Invasive species are those introduced species that spread-widely or quickly, and cause harm, be that to the environment, biodiversity, human health, other valued resources or the economy. There have been calls from scientists to consider a species "invasive" only in terms of their spread and reproduction rather than the harm they may cause. Colautti and MacIsaac 2004.

There is valid disagreement as to whether the term invasive species is exactly synonymous with introduced species. Introduced species|Weed Invasive species is a phrase with several definitions A species that is invasive is one that has been introduced and become a pest in its new location, spreading (invading) by natural means. The term is used to imply both a sense of urgency and actual or potential harm. For example, U. S. Executive Order 13112 (1999) defines "invasive species" as "an alien species whose introduction does or is likely to cause economic or environmental harm or harm to human health". ^[3]

Although some argue that "invasive" is a loaded word and harm is difficult to define,^[1] the fact of the matter is that organisms have and continue to be introduced to areas where they are not native, sometimes with, usually without, much regard to the harm that could result.

From a regulatory perspective, it is neither desirable nor practical to simply list as undesirable or outright ban all non-native species (although the State of Hawaii has adopted an approach that comes close to this). The State of Hawaii ( or həˈwaɪʔiː Hawaiian: Mokuāina o Hawaii) is a state in the United States located on an Archipelago in the Regulations require a definitional distinction between non-natives that are deemed especially onerous and all others. Introduced pest species that are officially listed as invasive, best fit the definition of an invasive species.

Nature of introductions

By definition, a species is considered “introduced” when its transport into an area outside of its native range is human mediated. The terminology in this page contains definitions for invasion biology terms in common usage today taken from accessible publications Introductions by humans can be described as either intentional or accidental. Intentional introductions have been motivated by individuals or groups who believe that the newly introduced species will be in some way beneficial to humans in its new location. Unintentional or accidental introductions are most often a byproduct of human movements, and are thus unbound to human motivations. Subsequent range expansion of introduced species may or may not involve human activity.

Intentional introductions

Species that humans intentionally transport to new regions can subsequently become successfully established in two ways. In the first case, organisms are purposely released for establishment in the wild. It is sometimes difficult to predict whether a species will become established upon release, and if not initially successful, humans have made repeated introductions to improve the probability that the species will survive and eventually reproduce in the wild. In these cases it is clear that the introduction is directly facilitated by human desires.

In the second case, species intentionally transported into a new region may escape from captive or cultivated populations and subsequently establish independent breeding populations. Escaped organisms are included in this category because their initial transport to a new region is human motivated.

Perhaps the most common motivation for introducing a species into a new place is that of economic gain. Examples of species introduced for the purposes of benefiting agriculture, aquaculture or other economic activities are widespread. Agriculture refers to the production of goods through the growing of plants and fungi and the raising of domesticated Animals The study of agriculture Aquaculture is the farming of freshwater and saltwater organisms including Molluscs Crustaceans and aquatic plants ^[4] Eurasian carp was first introduced to the United States as a potential food source. The apple snail was released in Southeast Asia with the intent that it be used as a protein source, and subsequently to places like Hawaiʻi to establish a food industry. The family Ampullariidae - commonly referred to as apple Snails - are large Tropical and Subtropical Amphibious In Alaska, foxes were introduced to many islands to create new populations for the fur trade. The timber industry promoted the introduction of Monterey Pine (Pinus radiata) from California to Australia and New Zealand as a commercial timber crop. These examples represent only a small subsample of species that have been moved by humans for economic interests.

Introductions have also been important in supporting recreation activities or otherwise increasing human enjoyment. Numerous fish and game animals have been introduced for the purposes of sport fishing and hunting. The introduced amphibian (Ambystoma tigrinum) that threatens the endemic California salamander (Ambystoma californiense) was introduced to California as a source of bait for fishermen. ^[5] Pet animals have also been frequently transported into new areas by humans, and their escapes have resulted in several successful introductions, such as those of feral cats and parrots.

Many plants have been introduced with the intent of aesthetically improving public recreation areas or private properties. The introduced Norway Maple for example occupies a prominent status in many of Canada's parks. Acer platanoides ( Norway Maple) is a species of Maple native to eastern and central Europe and southwest Asia, from France ^[6] The transport of ornamental plants for landscaping use has and continues to be a source of many introductions. Ornamental plants are typically grown in the flower Garden or as House plants Most commonly they are grown for the display of their Flowers Other common Some of these species have escaped horticultural control and become invasive. Notable examples include water hyacinth, salt cedar, and purple loosestrife. The seven species of water hyacinths comprise the genus Eichhornia. Tamarisk redirects here For other uses of tamarisk see Tamarisk (disambiguation The genus Tamarix ( tamarisk Lythrum salicaria ( Purple-loosestrife) is a Flowering plant belonging to the family Lythraceae, native to Europe, Asia

In other cases, species have been translocated for reasons of “cultural nostalgia,” which refers to instances in which humans who have migrated to new regions have intentionally brought with them familiar organisms. Famous examples include the introduction of starlings to North America by Englishman Eugene Schieffelin, a lover of the works of Shakespeare, who, it is rumoured, wanted to introduce all of the birds mentioned in Shakespeare's plays into the United States. Eugene Schieffelin ( 29 January 1827, New York NY, — 15 August 1906, Newport Rhode Island) belonged to the New York He deliberately released eighty starlings into Central Park in New York City in 1890, and another forty in 1891. Yet another prominent example is the introduction of the European rabbit to Australia by one Thomas Austin, a British landowner who had the rabbits released on his estate in Victoria because he missed hunting them. The European Rabbit ( Oryctolagus cuniculus) is a species of Rabbit native to south west Europe (Spain and Portugal For a topic outline on this subject see List of basic Australia topics. Thomas Austin (1815 – 1871 was a pioneer settler in Van Diemen’s Land and Winchelsea, Victoria Australia, and is generally credited with the introduction A more recent example is the introduction of the wall lizard to North America by a Cincinnati boy, George Rau, in the 1950s after a family vacation to Italy. The common wall lizard ( Podarcis muralis) is a species of Lizard with a large distribution in Europe and well-established introduced populations in ^[7]

Intentional introductions have also been undertaken with the aim of ameliorating environmental problems. A number of fast spreading plants such as Garlic Mustard and kudzu have been introduced as a means of erosion control. Pueraria lobata (syn P montana P thunbergiana) (sometimes known as foot a night vine, mile a minute vine, Gat Gun, Ge Gan and Erosion is the carrying away or displacement of solids ( Sediment, Soil, rock and other particles usually by the agents of currents such as wind Other species have been introduced as biological control agents to control invasive species and involves the purposeful introduction of a natural enemy of the target species with the intention of reducing its numbers or controlling its spread. Biological control of pests in Agriculture is a method of controlling pests (including Insects Mites Weeds and plant diseases

A special case of introduction is the reintroduction of a species that has become locally endangered or extinct, done in the interests of conservation. Examples of successful reintroductions include wolves to Yellowstone National Park in the U. S. , and the Red kite to parts of England and Scotland. The Red Kite ( Milvus milvus) is a medium-large Bird of prey in the family Accipitridae, which also includes many other diurnal raptors such Introductions or translocations of species have also been proposed in the interest of genetic conservation, which advocates the introduction of new individuals into genetically depauperate populations of endangered or threatened species. Conservation refers to a high degree of similarity in orthologous DNA sequences protein sequences, or Protein structures amongst various ^[8]

The above examples highlight the intent of humans to introduce species as a means of incurring some benefit. While these benefits have in some cases been realized, introductions have also resulted in unforeseen costs, particularly when introduced species take on characteristics of invasive species.

Accidental introductions

Unintentional introductions occur when species are transported by human vectors. For example, three species of rat (the Black, Norway and Polynesian) have spread to most of the world as hitchhikers on ships. Rats are various medium sized long-tailed Rodents of the superfamily Muroidea There are also numerous examples of marine organisms being transported in ballast water, one being the zebra mussel. The zebra mussel, Dreissena polymorpha, is a Species of small freshwater Mussel, an Aquatic Bivalve Mollusk. Over 200 species have been introduced to the San Francisco Bay in this manner making it the most heavily invaded estuary in the world. San Francisco Bay is a shallow productive Estuary through which water draining from approximately forty percent of California, flowing in the Sacramento ^[9] Increasing rates of human travel are providing accelerating opportunities for species to be accidentally transported into areas in which they are not considered native.

Introduced plants and algae

Many non-native plants have been introduced into new territories, initially as either ornamental plants or for erosion control, stock feed, or forestry. Ornamental plants are typically grown in the flower Garden or as House plants Most commonly they are grown for the display of their Flowers Other common Erosion is the carrying away or displacement of solids ( Sediment, Soil, rock and other particles usually by the agents of currents such as wind Whether an exotic will become invasive is seldom understood in the beginning, and many non-native ornamentals languish in the trade for years before suddenly naturalizing and becoming invasive.

Peaches, for example, originated in Persia, and have been carried to much of the populated world. Tomatoes are native to the Andes. Squash (pumpkins), maize, and tobacco are native to the Americas, but were introduced to the Old World. Many introduced species require continued human intervention to survive in the new environment. Others may become feral, but do not seriously compete with natives, but simply increase the biodiversity of the area. Interspecific competition, in Ecology, is a form of competition in which individuals of different Species vie for the same resource in an ecosystem

Dandelions are also introduced species to North America.

A very troublesome marine species in southern Europe is the seaweed Caulerpa taxifolia. Seaweed is a loose colloquial term encompassing macroscopic Multicellular, benthic marine Algae. Caulerpa taxifolia is a species of Seaweed, an Alga of the Genus Caulerpa. Caulerpa was first observed in the Mediterranean Sea in 1984, off the coast of Monaco. Year 1984 ( MCMLXXXIV) was a Leap year starting on Sunday (link displays the 1984 Gregorian calendar) For other uses see Monaco (disambiguation Monaco, officially the Principality of Monaco ( French: Principauté de Monaco; Monégasque By 1997, it had covered some 50 km². Year 1997 ( MCMXCVII) was a Common year starting on Wednesday (link will display full 1997 Gregorian calendar It has a strong potential to overgrow natural biotopes, and represents a major risk for sublittoral ecosystems. Biotope is an area of uniform environmental conditions providing a living place for a specific assemblage of plants and animals. An ecosystem is a natural unit consisting of all plants animals and micro-organisms( Biotic factors in an area functioning together with all of the non-living physical ( The origin of the alga in the Mediterranean was thought to be either as a migration through the Suez Canal from the Red Sea, or as an accidental introduction from an aquarium. The Suez Canal is a Canal in Egypt. Opened in 1869 it allows Water transportation between Europe and Asia without circumnavigation

Japanese knotweed grows profusely in many nations. Japanese knotweed ( Fallopia japonica, syn Polygonum cuspidatum, Reynoutria japonica) is a large Herbaceous Perennial plant Human beings introduced it into many places in the 19th century. It is a source of resveratrol, a dietary supplement. Resveratrol is a Phytoalexin produced naturally by several Plants when under attack by Pathogens such as Bacteria or Fungi

Introduced animals

Male Lophura nycthemera (Silver Pheasant), a native of East Asia that has been introduced into parts of Europe for ornamental reasons. The Silver Pheasant, Lophura nycthemera is a large approximately 125cm long white Pheasant with bare red facial skin red legs and glossy black below

One example of introducing an exotic animal was carried out by a lover of the works of Shakespeare, who wanted to introduce all of the birds mentioned in Shakespeare's plays into the United States. William Shakespeare ( baptised The United States of America —commonly referred to as the He deliberately released eighty starlings into Central Park in New York City in 1890, and another forty in 1891. The European Starling, Common Starling or just Starling, Sturnus vulgaris, is a Passerine Bird in the family Central Park is a large public Urban park in New York City, with about twenty-five million visitors annually The City of New York Year 1890 ( MDCCCXC) was a Common year starting on Wednesday (link will display the full calendar of the Gregorian calendar (or a Common Year 1891 ( MDCCCXCI) was a Common year starting on Thursday (link will display the full calendar of the Gregorian calendar (or a Common The starling had been introduced previously into Ohio and had failed to survive. Ohio ( is a Midwestern state of the United States. As part of the Great Lakes region, Ohio has long been a cultural and geographical crossroads

Other examples of introduced animals include the gypsy moth in eastern North America, the zebra mussel and alewife in the Great Lakes, the Canada Goose and Gray Squirrel in Europe, the Muskrat in Europe and Asia, the Cane Toad and Red fox in Australia, and the Common Brushtail Possum in New Zealand. The gypsy moth, Lymantria dispar, is a moth in the family Lymantriidae of Eurasian origin The zebra mussel, Dreissena polymorpha, is a Species of small freshwater Mussel, an Aquatic Bivalve Mollusk. The alewife ( Alosa pseudoharengus) is a species of Herring. There are anadromous and landlocked forms The Laurentian Great Lakes are a chain of freshwater lakes located in eastern North America, on the Canada–United States border. The Canada Goose ( Branta canadensis) is a Goose belonging to the Genus Branta native to North America. The eastern gray squirrel ( Sciurus carolinensis) is a Tree squirrel native to the eastern and Midwestern United States and to the southerly The muskrat ( Ondatra zibethicus) the only Species in Genus Ondatra, is a medium-sized semi-aquatic Rodent native to North America The Red Fox ( Vulpes vulpes) is a Mammal of the order Carnivora. The Common Brushtail Possum ( Trichosurus vulpecula, from the Greek for "furry tailed" and the Latin for "little fox" is the largest New Zealand is an Island country in the south-western Pacific Ocean comprising two main landmasses (the North Island and the South Island

Invasive exotic diseases

History is rife with the spread of exotic diseases, such as the introduction of smallpox into the Americas, where it obliterated entire Native American civilizations before they were ever even seen by Europeans. Smallpox is an Infectious disease unique to humans caused by either of two virus variants named Variola major and Variola minor. For indigenous peoples in the United States other than Hawaii and Alaska see also Native Americans in the United States.

Problematic exotic disease introductions in the past century or so include the chestnut blight which has virtually extinguished the American chestnut, and Dutch elm disease, which has severely damaged the American elm. The chestnut blight is a fungal disease caused by the sac fungus ( Ascomycota) Cryphonectria parasitica (formerly Endothia parasitica) which The American Chestnut ( Castanea dentata) is a large Deciduous tree of the oak family native to eastern North America Dutch elm disease (DED is a fungal disease of Elm trees which is spread by the Elm bark beetle. Ulmus americana, generally known as the American Elm or less commonly as the White Elm or Water Elm, is a species native to eastern

Most commonly introduced species

Some species, such as the Brown Rat, House Sparrow, Ring-necked Pheasant and European Starling, have been introduced very widely. The House Sparrow ( Passer domesticus) is a member of the Old World Sparrow family Passeridae, considered by some to be a relative of the The Common Pheasant ( Phasianus colchicus) is a bird in the Pheasant family (Phasianidae The European Starling, Common Starling or just Starling, Sturnus vulgaris, is a Passerine Bird in the family In addition there are some agricultural and pet species that frequently become feral; these include rabbits, dogs, goats, fish, pigs and cats. Agriculture refers to the production of goods through the growing of plants and fungi and the raising of domesticated Animals The study of agriculture A pet is an Animal kept for companionship and enjoyment or a househeld animal as opposed to Livestock, Laboratory animals Working animals A feral organism is one that has escaped from Domestication and returned partly or wholly to its wild state Rabbits are small Mammals in the family Leporidae of the order Lagomorpha, found in several parts of the world The dog ( Canis lupus familiaris) is a domesticated Subspecies of the gray wolf, a Mammal of the Canidae family of the order The domestic goat ( Capra aegagrus hircus) is a subspecies of goat Domesticated from the Wild goat of Southwest Asia and Eastern Europe Fish are aquatic Vertebrate animals that are typically ectothermic (previously Cold-blooded) covered with scales, and equipped with two Pigs, also called hogs or' swine', are Ungulates which have been domesticated as sources of food leather and similar products since ancient times WikipediaManual of Style (spelling, articles should conform to one overall spelling style of English typically the one most linked to the article topic (if it is geographic

Introduced species on islands

Perhaps the best place to study problems associated with introduced species is on islands. Depending upon the isolation (how far an island is located from continental biotas), native island biological communities may be poorly adapted to the threat posed by exotic introductions. Often this can mean that no natural predator of an introduced species is present, and the non-native spreads uncontrollably into open or occupied niche. In Ecology, a niche (pronounced nich nēsh or nish A shorthand definition of niche is how an organism makes a living

An additional problem is that birds native to small islands may have become flightless due to the absence of predators prior to introductions, and cannot readily escape danger. The tendency of rails in particular to evolve flightless forms on islands has led to the disproportionate number of extinctions in that family. The rails, or Rallidae, are a large cosmopolitan family of small to medium-sized Birds The family exhibits considerable diversity

The field of island restoration has developed as a field of conservation biology and ecological restoration, a great deal of which deals with the eradication of introduced species. The ecological restoration of islands, or island restoration, is the application of the principles of Ecological restoration to Islands and island groups "Conservation Biology" redirects here For the Scientific journal, see Conservation Biology (journal. Restoration ecology is the study of renewing a degraded damaged or destroyed Ecosystem through active human intervention

New Zealand

Main article: Introduced species in New Zealand

In New Zealand the largest commercial crop is Pinus radiata, the Monterey Pine from California, which grows better in New Zealand than in California. New Zealand 's short human history has resulted in a number of serious plant and animal pests New Zealand is an Island country in the south-western Pacific Ocean comprising two main landmasses (the North Island and the South Island Pinus radiata (family Pinaceae is known in English as Monterey Pine in some parts of the world (mainly in the USA, Canada and the California ( is a US state on the West Coast of the United States, along the Pacific Ocean. However, the pine forests are also occupied by deer from North America and Europe and by possums from Australia. A deer is a Ruminant Mammal belonging to the family Cervidae. A possum is any of about 64 small to medium-sized Arboreal Marsupial Species native to Australia, New Guinea, and Sulawesi For a topic outline on this subject see List of basic Australia topics. All are exotic species and all have thrived in the New Zealand environment. The pines are seen as beneficial while the deer and possums are regarded as serious pests.

Common gorse, originally a hedge plant in Scotland, was introduced to New Zealand for the same purpose. Gorse ( Ulex) comprises a Genus of about 20 species of Evergreen Shrubs in the subfamily Faboideae of the pea family Scotland ( Gaelic: Alba) is a Country in northwest Europethat occupies the northern third of the island of Great Britain. Like the radiata pine, it has shown a favour to its new climate and is regarded as a noxious plant which threatens to obliterate native plants in much of the country and is hence routinely eradicated, though it can also provide a nursery environment for native plants to reestablish themselves.

Rabbits, introduced as a food source by sailors in the 1800s, have become a severe nuisance to farmers, notably in South Island. Rabbits are small Mammals in the family Leporidae of the order Lagomorpha, found in several parts of the world The myxomatosis virus was illegally imported and illegally released but it had little lasting effect upon the rabbit population other than to make it more resistant to the virus. Myxomatosis (commonly called 'myxi' is a disease which affects Rabbits It is caused by the Myxoma virus. A virus (from the Latin virus meaning Toxin or Poison) is a sub-microscopic infectious agent that is unable

Rats, brought either by the first humans to arrive in New Zealand (the Maori) or by Europeans have had a devastating effect upon native birdlife, particularly as many New Zealand birds are flightless. This article discusses the Māori people of New Zealand For their language see Māori language, and for other meanings see Māori (disambiguation. Feral cats and dogs which were originally brought as pets are also known to kill large numbers of birds. A recent (2006) study in South Island has shown that even domestic cats with a ready supply of food from their owners may kill hundreds of birds in a year, including natives.

Sparrows, which were brought to control insects upon the introduced grain crops, have displaced native birds as have Rainbow Lorikeets and cockatoos (both from Australia) which fly free around areas west of Auckland City such as the Waitakere Ranges. The "true sparrows" the Old World sparrows in the family Passeridae, are small Passerine Birds Generally sparrows tend to be The Rainbow Lorikeet, Trichoglossus haematodus is a species of Australasian Parrot found in Australia, eastern Indonesia, Papua A cockatoo is any of the 20 Bird Species belonging to the family Cacatuidae. The Auckland metropolitan area or Greater Auckland, in the North Island of New Zealand, is the largest and most populous urban area in the country The Waitakere Ranges are a chain of hills generally running approximately 25 km (15

In much of the New Zealand the Australian black swan has effectively eliminated the existence of the previously introduced mute swan. The Black Swan ( Cygnus atratus) is a large waterbird which breeds mainly in the southeast and southwest regions of Australia. The Mute Swan ( Cygnus olor) is a Eurasian member of the Duck, Goose and Swan family Anatidae.

Two notable varieties of spiders have also been introduced: the white tail spider and the black widow spider. The white-tailed spider, (common species are Lampona cylindrata, Lampona murina) are medium-sized Spiders from southern and eastern Australia The black widow spider is a group of Spiders which includes the southern black widow ( Latrodectus mactans) the northern black widow Both may have arrived inside shipments of fruit. Prior to this the only spider (and the only poisonous animal) dangerous to humans was the native katapo which is very similar to the black widow and which is known to successfully interbreed with the more aggressive North American variety.

Genetic pollution

Main article: Genetic pollution

Purebred naturally evolved region specific wild species can be threatened with extinction in a big way^[10] through the process of genetic pollution i. Genetic pollution is undesirable Gene flow into wild populations In Biology, a species is one of the basic units of Biological classification and a Taxonomic rank. In Biology and Ecology, extinction is the cessation of existence of a Species or group of taxa. Genetic pollution is undesirable Gene flow into wild populations e. uncontrolled hybridization, introgression and genetic swamping which leads to homogenization or replacement of local genotypes as a result of either a numerical and/or fitness advantage of introduced plant or animal^[11]. Introgression, in Genetics (particularly plant genetics is the movement of a Gene ( Gene flow) from one species into the gene pool of another by backcrossing The genotype is the genetic constitution of a cell an organism or an individual (i Fitness (often denoted w in Population genetics models is a central concept in evolutionary theory. Nonnative species can bring about a form of extinction of native plants and animals by hybridization and introgression either through purposeful introduction by humans or through habitat modification, bringing previously isolated species into contact. These phenomena can be especially detrimental for rare species coming into contact with more abundant ones where the abundant ones can interbreed with them swamping the entire rarer gene pool creating hybrids thus driving the entire original purebred native stock to complete extinction. Attention has to be focused on the extent of this under appreciated problem that is not always apparent from morphological (outward appearance) observations alone. The term morphology in Biology refers to the outward appearance ( Shape, Structure, Colour, Pattern) of an Organism Some degree of gene flow may be a normal, evolutionarily constructive process, and all constellations of genes and genotypes cannot be preserved however, hybridization with or without introgression may, nevertheless, threaten a rare species' existence^[12][13]. In Population genetics, gene flow (also known as gene migration) is the transfer of Alleles of Genes from one Population to another History See also History of genetics The existence of genes was first suggested by Gregor Mendel (1822-1884 who in the 1860s studied inheritance The genotype is the genetic constitution of a cell an organism or an individual (i

See also

• Biodiversity
• Biological dispersal
• Invasion biology terminology
• Invasive species
• List of introduced species
• List of introduced bird species
• Genetic pollution

References

1. ^ ^{a b} Carlton, James T. Biodiversity is the variation of Life forms within a given Ecosystem, Biome or for the entire Earth. Biological dispersal refers to those processes by which a Species maintains ecosystem The terminology in this page contains definitions for invasion biology terms in common usage today taken from accessible publications Introduced species|Weed Invasive species is a phrase with several definitions A complete List of introduced species for even quite small areas of the world would be dauntingly long This list of introduced bird species includes all the species of bird successfully or unsuccessfully introduced to an area other than their native range or to an area they formerly inhabited Genetic pollution is undesirable Gene flow into wild populations 2002. Introduced Species in U. S. Coastal Waters. Pew Oceans Commission.
2. ^ U. S. Environmental Protection Agency. Mid-Atlantic Integrated Assessment. September 16, 2003. Introduced species. Web site at US EPA
3. ^ CEQ (1999). Web site page with Executive Order 13112 text.
4. ^ Naylor, R. L. , S. L. Williams, and D. R. Strong. 2001. Aquaculture—a gateway for exotic species. Science 294: 1655-56.
5. ^ Riley, SPD, H. B. Shaffer, S. R. Voss, B. M. Fitzpatrick. Hybridization between a rare, native tiger salamander and its introduced congener. 2003. Ecological Applications 13: 1263–1275.
6. ^ Foster, J. and A. Sandberg. Friends or foe? Invasive species and public green space in Toronto. 2004. The Geographical Review 94: 178-198.
7. ^ Deichsel, G. & Gist, D. H. On the Origin of the Common Wall Lizards Podarcis muralis (Reptilia: Lacertidae) in Cincinnati, Ohio
8. ^ Moritz, Craig. 1999. Conservation units and translocations: Strategies for conserving evolutionary processes. Hereditas 130: 217-228.
9. ^ Cohen, A. N. And J. T. Carlton. 1998. Accelerating invasion rate in a highly invaded estuary. Science 279: 555-558.
10. ^ Hybridization and Introgression; Extinctions; from "The evolutionary impact of invasive species; by H. A. Mooney and E. E. Cleland" Proc Natl Acad Sci U S A. 2001 May 8; 98(10): 5446–5451. doi: 10.1073/pnas.091093398. Proc Natl Acad Sci U S A, v.98(10); May 8, 2001, The National Academy of Sciences
11. ^ Glossary: definitions from the following publication: Aubry, C., R. Shoal and V. Erickson. 2005. Grass cultivars: their origins, development, and use on national forests and grasslands in the Pacific Northwest. USDA Forest Service. 44 pages, plus appendices.; Native Seed Network (NSN), Institute for Applied Ecology, 563 SW Jefferson Ave, Corvallis, OR 97333, USA
12. ^ EXTINCTION BY HYBRIDIZATION AND INTROGRESSION; by Judith M. Rhymer , Department of Wildlife Ecology, University of Maine, Orono, Maine 04469, USA; and Daniel Simberloff, Department of Biological Science, Florida State University, Tallahassee, Florida 32306, USA; Annual Review of Ecology and Systematics, November 1996, Vol. 27, Pages 83-109 (doi: 10.1146/annurev.ecolsys.27.1.83), [1]
13. ^ Genetic Pollution from Farm Forestry using eucalypt species and hybrids; A report for the RIRDC/L&WA/FWPRDC; Joint Venture Agroforestry Program; by Brad M. Potts, Robert C. Barbour, Andrew B. Hingston; September 2001; RIRDC Publication No 01/114; RIRDC Project No CPF - 3A; ISBN 0 642 58336 6; ISSN 1440-6845; Australian Government, Rural Industrial Research and Development Corporation

External links

• Alien Plants in Ireland Database of Alien plants in Ireland
• Introduced species in the British Isles
• Alien species in Poland
• Introduced Species in Eastern United States
• Pathways for Invasive Species Introduction