Introduced species Sweet clover (Melilotus sp.), introduced and naturalized to the U.S. from Eurasia as a for- age and cover crop. A species is defined as introduced (also known as non-indigenous, alien or exotic) in a certain geographical area, if that area is outside the species’ native distributional range, and the species has arrived there by human activity. Introduced species some- times 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. Introduced spe- cies and their effects on natural environ- ments is a controversial subject and one that has gained much scrutiny by scientists, gov- ernments, farmers and others. Terminology The terminology associated with introduced species is presently in flux for a variety of reasons. Other terms that are used some- times interchangeably (having the same or similar meanings) with introduced are accli- matized, adventive, native, naturalized, im- migrant, 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 consider- ation as introduced all of those species raised or grown in gardens or farms that do not sur- vive 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, al- though perhaps lacking ecological sophistica- tion, 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 spe- cies that may only occur in cultivation, under domestication or captivity whereas other be- come 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 de- scribed by in the context of plants.[3] Intro- duced species are essentially "non-native" species. Invasive species are those intro- duced species that spread-widely or quickly, and cause harm, be that to the environ- ment,[4] human health, other valued re- sources or the economy. There have been calls from scientists to consider a species "in- vasive" only in terms of their spread and re- production rather than the harm they may cause.[5]. From Wikipedia, the free encyclopedia Introduced species 1 There is disagreement as to whether the term invasive species is exactly synonymous with introduced species. A species that is in- vasive 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 ac- tual or potential harm. For example, U.S. Ex- ecutive Order 13112 (1999) defines "invasive species" as "an alien species whose introduc- tion does or is likely to cause economic or en- vironmental harm or harm to human health".[6] 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 ad- opted an approach that comes close to this). Regulations require a definitional distinction between non-natives that are deemed espe- cially onerous and all others. Introduced pest species that are officially listed as invasive, best fit the definition of an invasive species. Table of terms related to "Introduced Species" NATIVE NON-NATIVE INTRODUCED (broad definition) Established in the wild INTRODUCED (narrow definition) INDIGENOUS or ENDEMIC CULTIVATED and LIVESTOCK INVASIVE (pest) All others not listed* *Not listed in any "official" source as a pest species Nature of introductions By definition, a species is considered “intro- duced” when its transport into an area out- side of its native range is human mediated. Introductions by humans can be described as either intentional or accidental. Intentional introductions have been motivated by indi- viduals or groups who believe that the newly introduced species will be in some way bene- ficial to humans in its new location. Uninten- tional or accidental introductions are most of- ten a byproduct of human movements, and are thus unbound to human motivations. Sub- sequent range expansion of introduced spe- cies may or may not involve human activity. Intentional introductions Species that humans intentionally transport to new regions can subsequently become suc- cessfully established in two ways. In the first case, organisms are purposely released for establishment in the wild. It is sometimes dif- ficult to predict whether a species will be- come established upon release, and if not ini- tially successful, humans have made re- peated introductions to improve the probabil- ity that the species will survive and eventu- ally reproduce in the wild. In these cases it is clear that the introduction is directly facilit- ated 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 trans- port 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 intro- duced for the purposes of benefiting agricul- ture, aquaculture or other economic activit- ies are widespread.[7] 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 in- dustry. 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 ra- diata) 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 From Wikipedia, the free encyclopedia Introduced species 2 tigrinum) that threatens the endemic Califor- nia salamander (Ambystoma californiense) was introduced to California as a source of bait for fishermen.[8] 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 occu- pies a prominent status in many of Canada’s parks.[9] The transport of ornamental plants for landscaping use has and continues to be a source of many introductions. Some of these species have escaped horticultural control and become invasive. Notable examples in- clude water hyacinth, salt cedar, and purple loosestrife. In other cases, species have been translo- cated for reasons of “cultural nostalgia,” which refers to instances in which humans who have migrated to new regions have in- tentionally brought with them familiar organ- isms. Famous examples include the introduc- tion of starlings to North America by English- man 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. 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 re- leased on his estate in Victoria because he missed hunting them. 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.[10] Intentional introductions have also been undertaken with the aim of ameliorating en- vironmental problems. A number of fast spreading plants such as Garlic Mustard and kudzu have been introduced as a means of erosion control. Other species have been in- troduced as biological control agents to con- trol invasive species and involves the pur- poseful introduction of a natural enemy of the target species with the intention of redu- cing its numbers or controlling its spread. A special case of introduction is the rein- troduction of a species that has become loc- ally endangered or extinct, done in the interests of conservation. Examples of suc- cessful reintroductions include wolves to Yel- lowstone National Park in the U.S., and the Red kite to parts of England and Scotland. In- troductions or translocations of species have also been proposed in the interest of genetic conservation, which advocates the introduc- tion of new individuals into genetically de- pauperate populations of endangered or threatened species.[11] 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, introduc- tions have also resulted in unforeseen costs, particularly when introduced species take on characteristics of invasive species. Non-native species can become such a common part of an environment, culture, and even diet that little thought is given to their geographic origin. For example, soybeans, kiwi fruit, wheat and all livestock except the llama and the turkey are non-native species to North America. Collectively, non-native crops and livestock comprise 98% of US food.[12] These and other benefits from non- natives are so vast that, according to the Congressional Research Service, they prob- ably exceed the costs.[13] Accidental introductions Unintentional introductions occur when spe- cies are transported by human vectors. For example, three species of rat (the Black, Nor- way and Polynesian) have spread to most of the world as hitchhikers on ships. There are also numerous examples of marine organisms being transported in ballast water, one being the zebra mussel. Over 200 species have been introduced to the San Francisco Bay in this manner making it the most heavily in- vaded estuary in the world.[14] Increasing rates of human travel are providing acceler- ating opportunities for species to be acci- dentally 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 orna- mental plants or for erosion control, stock feed, or forestry. Whether an exotic will be- come invasive is seldom understood in the beginning, and many non-native ornamentals From Wikipedia, the free encyclopedia Introduced species 3 languish in the trade for years before sud- denly naturalizing and becoming invasive. Peaches, for example, originated in Persia, and have been carried to much of the popu- lated world. Tomatoes are native to the Andes. Squash (pumpkins), maize, and to- bacco are native to the Americas, but were introduced to the Old World. Many intro- duced species require continued human in- tervention to survive in the new environment. Others may become feral, but do not seri- ously compete with natives, but simply in- crease the biodiversity of the area. Dandelions are also introduced species to North America. A very troublesome marine species in southern Europe is the seaweed Caulerpa taxifolia. Caulerpa was first observed in the Mediterranean Sea in 1984, off the coast of Monaco. By 1997, it had covered some 50 km². It has a strong potential to overgrow natural biotopes, and represents a major risk for sublittoral ecosystems. 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 intro- duction from an aquarium. Japanese knotweed grows profusely in many nations. Human beings introduced it in- to many places in the 19th century. It is a source of resveratrol, a dietary supplement. Introduced animals Male Lophura nycthemera (Silver Pheasant), a native of East Asia that has been intro- duced into parts of Europe for ornamental reasons. 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. He deliberately re- leased eighty starlings into Central Park in New York City in 1890, and another forty in 1891. The starling had been introduced pre- viously into Ohio and had failed to survive. Other examples of introduced animals in- clude the gypsy moth in eastern North Amer- ica, 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, Nutria in North America, Eurasia, and Africa, and the Common Brushtail Possum in New Zealand. Invasive exotic diseases History is rife with the spread of exotic dis- eases, such as the introduction of smallpox into the Americas, where it obliterated entire Native American civilizations before they were ever even seen by Europeans. 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. Most commonly intro- duced species Some species, such as the Brown Rat, House Sparrow, Ring-necked Pheasant and European Starling, have been introduced very widely. In addition there are some agri- cultural and pet species that frequently be- come feral; these include rabbits, dogs, goats, fish, pigs and cats. Introduced species on islands Perhaps the best place to study problems as- sociated with introduced species is on is- lands. 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 uncon- trollably into open or occupied niche. An additional problem is that birds native to small islands may have become flightless From Wikipedia, the free encyclopedia Introduced species 4 because of 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 field of island restoration has de- veloped as a field of conservation biology and ecological restoration, a great deal of which deals with the eradication of introduced species. New Zealand In New Zealand the largest commercial crop is Pinus radiata, the Monterey Pine from Cali- fornia, which grows better in New Zealand than in California. However, the pine forests are also occupied by deer from North Amer- ica and Europe and by possums from Aus- tralia. 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. 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 environ- ment 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. 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. 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. 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. In much of the New Zealand the Australi- an black swan has effectively eliminated the existence of the previously introduced mute swan. Two notable varieties of spiders have also been introduced: the white tail spider and the black widow spider. 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 katipo which is very similar to the black widow and which is known to successfully interbreed with the more aggressive North American variety. Genetic pollution Purebred naturally evolved region specific wild species can be threatened with extinc- tion in a big way[15] through the process of genetic pollution i.e. uncontrolled hybridiza- tion, introgression and genetic swamping which leads to homogenization or replace- ment of local genotypes as a result of either a numerical and/or fitness advantage of intro- duced plant or animal[16]. Nonnative species can bring about a form of extinction of native plants and animals by hybridization and in- trogression either through purposeful intro- duction by humans or through habitat modi- fication, bringing previously isolated species into contact. These phenomena can be espe- cially detrimental for rare species coming in- to 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 al- ways apparent from morphological (outward appearance) observations alone. Some de- gree of gene flow may be a normal, evolution- arily constructive process, and all constella- tions of genes and genotypes cannot be pre- served however, hybridization with or without introgression may, nevertheless, threaten a rare species’ existence[17][18]. See also • Avian range expansion • Biodiversity From Wikipedia, the free encyclopedia Introduced species 5 • Biological dispersal • Genetic pollution • Invasion biology terminology • Invasive species • List of introduced bird species • List of introduced species References [1] ^ Carlton, James T. 2002. Introduced Species in U.S. Coastal Waters. Pew Oceans MArk RUles BitchezCommission. [2] U.S. Environmental Protection Agency. Mid-Atlantic Integrated Assessment. September 16, 2003. Introduced species. Web site at US EPA [3] http://www.ingentaconnect.com/content/ bsc/ddi/2000/00000006/00000002/ art00003= Richardson et al. 2000 [4] http://www.iucn.org/themes/ssc/ publications/policy/ invasivesEng.htm#anchor392619= biodiversity [5] http://www.blackwell-synergy.com/links/ doi/10.1111/j.1366-9516.2004.00061.x/ pdf= Colautti and MacIsaac 2004 [6] CEQ (1999). Web site page with Executive Order 13112 text. [7] Naylor, R.L., S.L. Williams, and D.R. Strong. 2001. Aquaculture—a gateway for exotic species. Science 294: 1655-56. [8] 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. [9] Foster, J. and A. Sandberg. Friends or foe? Invasive species and public green space in Toronto. 2004. The Geographical Review 94: 178-198. [10]Deichsel, G. & Gist, D. H. On the Origin of the Common Wall Lizards Podarcis muralis (Reptilia: Lacertidae) in Cincinnati, Ohio [11]Moritz, Craig. 1999. Conservation units and translocations: Strategies for conserving evolutionary processes. Hereditas 130: 217-228. [12]David Pimentel, Lori Lach, Rodolfo Zuniga, and Doug Morrison, Environmental and Economic Costs Associated with Non-Indigenous Species in the United States, College of Agriculture and Life Sciences, Cornell University (Ithaca, New York), June 12, 1999. [13]Corn; Tim Johnson, "Invasive Species," The Burlington Free Press, November 9, 2003 [14]Cohen, A.N. And J.T. Carlton. 1998. Accelerating invasion rate in a highly invaded estuary. Science 279: 555-558. [15]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 [16]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 [17]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] [18]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 From Wikipedia, the free encyclopedia Introduced species 6 • Pathways for Invasive Species Introduction • Nonindigenous Species Database Network Site received a 4-star (excellent) rating in a 2009 review. (Kevin Ahern, Ph.D. (2009), "GEN Best of the Web", Genetic Engineering & Biotechnology News 29 (8): 66 ) Retrieved from "http://en.wikipedia.org/wiki/Introduced_species" Categories: Introduced species, Biogeography, Conservation This page was last modified on 22 May 2009, at 00:13 (UTC). All text is available under the terms of the GNU Free Documentation License. (See Copyrights for details.) Wikipedia® is a registered trademark of the Wikimedia Foundation, Inc., a U.S. registered 501(c)(3) tax- deductible nonprofit charity. Privacy policy About Wikipedia Disclaimers From Wikipedia, the free encyclopedia Introduced species 7