Introduced species

An introduced species, alien species, exotic species, foreign species, non-indigenous species, or non-native species is a species living outside its native distributional range, but which has arrived there by human activity, either deliberate or accidental. Non-native species can have various effects on the local ecosystem. Introduced species that become established and spread beyond the place of introduction are called invasive species.

The impact of introduced species is highly variable. Some have a negative effect on a local ecosystem, while other introduced species may have no negative effect or only minor impact. Some species have been introduced intentionally to combat pests. They are called biocontrols and may be regarded as beneficial as an alternative to pesticides in agriculture for example. In some instances the potential for being beneficial or detrimental in the long run remains unknown.[1][2][3]

The effects of introduced species on natural environments have gained much scrutiny from scientists, governments, farmers and others.

Cattle Bos primigenius taurus introduced worldwide
Melilotus alba bgiu
Sweet clover (Melilotus sp.), introduced and naturalized to the Americas from Europe as a forage and cover crop.

Terminology: introduced species and subsets

The formal definition of an introduced species, from the United States Environmental Protection Agency, is A species that has been intentionally or inadvertently brought into a region or area. Also called an exotic or non-native species.[4]

There are many terms associated with introduced species that represent subsets of introduced species, and the terminology associated with introduced species is now in flux for various reasons. Examples of these terms are acclimatized, adventive, naturalized, and immigrant species but those terms refer to a subset of introduced species. The term "invasive" is used to describe introduced species when the introduced species causes substantial damage to the area in which it was introduced.

Subset descriptions:

Acclimatized species: Introduced species that have changed physically and/or behaviorally in order to adjust to their new environment. Acclimatized species are not necessarily optimally adjusted to their new environment and may just be physically/behaviorally sufficient for the new environment.
Adventive species
Naturalized species (plants): A naturalized plant species refers to a non-native plant that does not need human help to reproduce and maintain its population in an area that it is not native to.

General description of introduced species:

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",[5] which removes from consideration as introduced species that were 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.

Invasive species

Introduction of a species outside its native range is all that is required to be qualified as an "introduced species" such that one can distinguish between introduced species that may not occur except in cultivation, under domestication or captivity whereas others become established outside their native range and reproduce without human assistance. Such species might be termed "naturalized", "established", "wild non-native species". If they further spread beyond the place of introduction and cause damage to nearby species, they are called "invasive". The transition from introduction, to establishment and to invasion has been described in the context of plants.[6] Introduced species are essentially "non-native" species. Invasive species are those introduced species that spreadwidely or quickly and cause harm, be that to the environment,[7] 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.[8]

According to a practical definition, an invasive species 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".[9] The biological definition of invasive species, on the other hand, makes no reference to the harm they may cause, only to the fact that they spread beyond the area of original introduction.

Although some argue that "invasive" is a loaded word and harm is difficult to define,[5] the fact of the matter is that organisms have and continue to be introduced to areas in which they are not native, sometimes with but usually without much regard to the harm that could result.

From a regulatory perspective, it is neither desirable nor practical to list as undesirable or outright ban all non-native species (although the State of Hawaii has adopted an approach that comes close to this). 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. Early detection and rapid response is the most effective strategy for regulating a pest species and reducing economic and environmental impacts of an introduction [10]

In Great Britain, the Wildlife and Countryside Act 1981 prevents the introduction of any animal not naturally occurring in the wild or any of a list of both animals or plants introduced previously and proved to be invasive.

Nature of introductions

By definition, a species is considered "introduced" when its transport into an area outside of its native range is human mediated. Introductions by humans can be described as either intentional or accidental. Intentional introductions have been motivated by individuals or groups who either (1) believe that the newly introduced species will be in some way beneficial to humans in its new location or, (2) species are introduced intentionally but with no regard to the potential impact. 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.

Wheat Triticum introduced worldwide from its place of origin Mesopotamia.

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.

Male Silver Pheasant
Male Lophura nycthemera (silver pheasant), a native of East Asia that has been introduced into parts of Europe for ornamental reasons.

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.

Motivations for intentional introductions

Economic: Perhaps the most common motivation for introducing a species into a new place is that of economic gain. 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, honey bees, and all livestock except the American bison and the turkey are non-native species to North America. Collectively, non-native crops and livestock comprise 98% of US food.[11] These and other benefits from non-natives are so vast that, according to the Congressional Research Service, they probably exceed the costs.[12]

Other examples of species introduced for the purposes of benefiting agriculture, aquaculture or other economic activities are widespread.[13] 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 Hawaii to establish a food industry. In Alaska, foxes were introduced to many islands to create new populations for the fur trade. About twenty species of African and European dung beetles have established themselves in Australia after deliberate introduction by the Australian Dung Beetle Project in an effort to reduce the impact of livestock manure. 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.

The rise in the use of genetically modified organisms has added another potential economic advantage to introducing new/modified species into different environments. Companies such as Monsanto that earn much of their profit through the selling of genetically modified seeds has added to the controversy surrounding introduced species. The effect of genetically modified organisms varies from organism to organism and is still being researched today, however the rise of genetically modified organisms has added complexity to the conversations surrounding introduced species.

Human enjoyment

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 (earthworms as invasive species). The introduced amphibian (Ambystoma tigrinum) that threatens the endemic California salamander (Ambystoma californiense) was introduced to California as a source of bait for fishermen.[14] 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.[15] 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 include water hyacinth, salt cedar, and purple loosestrife

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 and the chairman of the American Acclimatization Society, 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 of an introduced species that became invasive is the European rabbit in Australia. Thomas Austin, a British landowner had rabbits released on his estate in Victoria because he missed hunting them. A more recent example is the introduction of the common wall lizard to North America by a Cincinnati boy, George Rau, around 1950 after a family vacation to Italy.[16]

Addressing environmental problems

Intentional introductions have also been undertaken with the aim of ameliorating environmental problems. A number of fast spreading plants such as kudzu have been introduced as a means of erosion control. 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.

A special case of introduction is the reintroduction of a species that has become locally endangered or extinct, done in the interests of conservation.[17] Examples of successful reintroductions include wolves to Yellowstone National Park in the U.S., and the red kite to parts of England and Scotland. 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.[18]

Unintentional introductions

Unintentional introductions occur when species are transported by human vectors. Increasing rates of human travel are providing accelerating opportunities for species to be accidentally transported into areas in which they are not considered native. For example, three species of rat (the black, Norway and Polynesian) have spread to most of the world as hitchhikers on ships, and arachnids such as scorpions and exotic spiders are sometimes transported to areas far beyond their native range by riding in shipments of tropical fruit. 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 invaded estuary in the world.[19] There is also the accidental release of the Africanized honey bees (AHB), known colloquially as "killer bees" or Africanized bee to Brazil in 1957 and the Asian carps to the United States. The insect commonly known as the brown marmorated stink bug (Halyomorpha halys) was introduced accidentally in Pennsylvania. Another form of unintentional introductions is when an intentionally introduced plant carries a parasite or herbivore with it. Some become invasive, for example the oleander aphid, accidentally introduced with the ornamental plant, oleander.

Most accidentally or intentionally introduced species do not become invasive as the ones mentioned above. For instance Some 179 coccinellid species have been introduced to the U.S. and Canada; about 27 of these non-native species have become established, and only a handful can be considered invasive, including the intentionally introduced Harmonia axyridis, multicolored Asian lady beetle.[20] However the small percentage of introduced species that become invasive can produce profound ecological changes. In North America Harmonia axyridis has become the most abundant lady beetle and probably accounts for more observations than all the native lady beetles put together.[21]

Introduced plants

Horse-chestnut 800
A horse chestnut tree, Aesculus hippocastanum. Native to Greece, it has been introduced across most of Europe and parts of North America as an ornamental plant. The horse chestnut tree is an example of a non-invasive introduced species, as while it is foreign it has naturalised and integrated into the ecosystems it was introduced to without apparent negative effects on native species there

Many non-native plants have been introduced into new territories, initially as either ornamental plants or for erosion control, stock feed, or forestry. Whether an exotic will become an invasive species 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 China, and have been carried to much of the populated world. Tomatoes are native to the Andes. Squash (pumpkins), maize (corn), 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.

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 introduction from an aquarium. Another troublesome plant species is the terrestrial plant Phyla canescens, which was intentionally introduced into many countries in North America, Europe, and Africa as an ornamental plant.[22][23] This species has become invasive in Australia, where it threatens native rare plants and causes erosion and soil slumping around river banks.[24] It has also become invasive in France where it has been listed as an invasive plant species of concern in the Mediterranean region, where it can form monocultures that threaten critical conservation habitats.[25]

Japanese knotweed grows profusely in many nations. Human beings introduced it into many places in the 19th century. It is a source of resveratrol, a dietary supplement.

Chickens Gallus gallus domesticus, from Asia, introduced in the rest of the world

Introduced animals

Most introduced species do not become invasive. Examples of introduced animals that have become invasive 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, nutria in North America, Eurasia, and Africa, and the common brushtail possum in New Zealand. In Taiwan, the success of introduced bird species was related to their native range size and body size; larger species with larger native range sizes were found to have larger introduced range sizes.[26]

One notoriously devastating introduced species is the Small Indian Mongoose (Herpestes Javanicus Auropunctatus). Originating in a region encompassing Iran and India, it was introduced to the West Indies and Hawaii in the late 1800s for pest control. Since it has thrived on prey unequipped to deal with its speed, nearly leading to the local extinction of a variety of species.[27]

Most commonly introduced 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 agricultural and pet species that frequently become feral; these include rabbits, dogs, ducks, goats, fish, pigs and cats.


When a new species is introduced, the species could potentially breed with members of native species, producing hybrids. The effect of the creating of hybrids can range from having little effect, a negative effect, to having devastating effects on native species. Potential negative effects include hybrids that are less fit for their environment resulting in a population decrease. This was seen in the Atlantic Salmon population when high levels of escape from Atlantic Salmon farms into the wild populations resulted in hybrids that had reduced survival.[28] Potential positive effects include adding to the genetic diversity of the population which can increase the adaptation ability of the population and increase the number of healthy individuals within a population. This was seen in the introduction of guppies in Trinidad to encourage population growth and introduce new alleles into the population. The results of this introduction included increased levels of heterozygosity and a larger population size.[29]

On a planetary body

It has been hypothesized that invasive species of microbial life could contaminate a planetary body after the former is introduced by a space probe or spacecraft, either deliberately or unintentionally.[30]

See also


  1. ^ Dov Sax, Aug 2008. The Proceedings of the National Academy of Sciences Archived July 6, 2012, at the Wayback Machine
  2. ^ "Foreign Species Overview". U.S. Fish and Wildlife Service - Endangered Species. Retrieved 28 May 2019.
  3. ^ "Foreign Species". NOAA Fisheries. Retrieved 28 May 2019.
  4. ^ U.S. Environmental Protection Agency. Mid-Atlantic Integrated Assessment. September 16, 2003. Introduced species. Web site at US EPA
  5. ^ a b Carlton, James T. 2002. Introduced Species in U.S. Coastal Waters. Pew Oceans Commission.
  6. ^ Richardson et al. 2000
  7. ^ biodiversity
  8. ^ A neutral terminology to define ‘invasive’ species - Colautti and MacIsaac 2004
  9. ^ CEQ (1999). Web site page with Executive Order 13112 Archived 2008-05-15 at the Wayback Machine text.
  10. ^ 2013. Invasive Species Program. Clemson University – DPI. Accessed 24 May 2013.
  11. ^ 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.
  12. ^ Corn; Tim Johnson, "Invasive Species," The Burlington Free Press, November 9, 2003
  13. ^ Naylor, R.L., S.L. Williams, and D.R. Strong. 2001. Aquaculture—a gateway for exotic species. Science 294: 1655–56.
  14. ^ 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.
  15. ^ Foster, J. and A. Sandberg. Friends or foe? Invasive species and public green space in Toronto. 2004. The Geographical Review 94: 178–198.
  16. ^ Deichsel, G. & Gist, D. H. On the Origin of the Common Wall Lizards Podarcis muralis (Reptilia: Lacertidae) in Cincinnati, Ohio Archived 2009-09-09 at the Wayback Machine
  17. ^ Shirey, P.D. and G.A. Lamberti. 2010. Assisted colonization under the U.S. Endangered Species Act. Conservation Letters 3(1): 45–52.
  18. ^ Moritz, Craig. 1999. Conservation units and translocations: Strategies for conserving evolutionary processes. Hereditas 130: 217–228.
  19. ^ Cohen, A.N. And J.T. Carlton. 1998. Accelerating invasion rate in a highly invaded estuary. Science 279: 555–558.
  20. ^ Field guide to recently introduced species of coccinellidae (Coleoptera) in North America, with a revised key to north American genera of coccinellini
  21. ^ Lost Ladybug Project
  22. ^ Kennedy, K. 1992. A systematic study of the genus Phyla Lour (Verbenaceae: Verbenoideae, Lantanae). University of Texas at Austin, Austin, Texas, USA.
  23. ^ Xu, Cheng-Yuan; Tang, Shaoqing; Fatemi, Mohammad; Gross, Caroline L.; Julien, Mic H.; Curtis, Caitlin; van Klinken, Rieks D. (2015-09-01). "Population structure and genetic diversity of invasive Phyla canescens: implications for the evolutionary potential". Ecosphere. 6 (9): art162. doi:10.1890/ES14-00374.1. ISSN 2150-8925.
  24. ^ Whalley, R. D. B.; Price, J. N.; Macdonald, M. J.; Berney, P. J. (2011). "Drivers of change in the Social-Ecological Systems of the Gwydir Wetlands and Macquarie Marshes in northern New South Wales, Australia". The Rangeland Journal. 33 (2): 109. doi:10.1071/rj11002.
  25. ^ Olivier, L., J. P. Galland, and H. Maurin, editors.1995. Livre Rouge de la flore menacée de France.Tome I. Espèces prioritaires. SPN-IEGB /MNHN, DNP/Ministère Environnement, CBN Porquerolles, Paris, France
  26. ^ Su, S.; Cassey, P.; Dyer, E. E.; Blackburn, T. M. (2017). "Geographical range expansion of alien birds and environmental matching". Ibis. 159 (1): 193–203. doi:10.1111/ibi.12418.
  27. ^ Lowe, Sarah (2000). "00 of the world's worst invasive alien species: a selection from the global invasive species database". Auckland: Invasive Species Specialist Group. 12: 10.
  28. ^ McGinnity, Philip; Prodöhl, Paulo; Ferguson, Andy; Hynes, Rosaleen; Maoiléidigh, Niall ó; Baker, Natalie; Cotter, Deirdre; O'Hea, Brendan; Cooke, Declan (2003-12-07). "Fitness reduction and potential extinction of wild populations of Atlantic salmon, Salmo salar, as a result of interactions with escaped farm salmon". Proceedings of the Royal Society of London B: Biological Sciences. 270 (1532): 2443–2450. doi:10.1098/rspb.2003.2520. ISSN 0962-8452. PMC 1691531. PMID 14667333.
  29. ^ Fitzpatrick, Sarah W.; Gerberich, Jill C.; Angeloni, Lisa M.; Bailey, Larissa L.; Broder, Emily D.; Torres-Dowdall, Julian; Handelsman, Corey A.; López-Sepulcre, Andrés; Reznick, David N. (2016-08-01). "Gene flow from an adaptively divergent source causes rescue through genetic and demographic factors in two wild populations of Trinidadian guppies". Evolutionary Applications. 9 (7): 879–891. doi:10.1111/eva.12356. ISSN 1752-4571. PMC 4947150. PMID 27468306.
  30. ^ Assessment of Planetary Protection and Contamination Control Technologies for Future Planetary Science Missions Archived 2014-03-19 at the Wayback Machine, Jet Propulsion Laboratory, January 24, 2011
    3.1.1 Microbial Reduction Methodologies:

    This protocol was defined in concert with Viking, the first mission to face the most stringent planetary protection requirements; its implementation remains the gold standard today.

External links

Bird conservation

Bird conservation is a field in the science of conservation biology related to threatened birds. Humans have had a profound effect on many bird species. Over one hundred species have gone extinct in historical times, although the most dramatic human-caused extinctions occurred in the Pacific Ocean as humans colonised the islands of Melanesia, Polynesia and Micronesia, during which an estimated 750-1800 species of bird became extinct. According to Worldwatch Institute, many bird populations are currently declining worldwide, with 1,200 species facing extinction in the next century. The biggest cited reason surrounds habitat loss. Other threats include overhunting, accidental mortality due to structural collisions, long-line fishing bycatch, pollution, competition and predation by pet cats, oil spills and pesticide use and climate change. Governments, along with numerous conservation charities, work to protect birds in various ways, including legislation, preserving and restoring bird habitat, and establishing captive populations for reintroductions.

See Late Quaternary prehistoric birds for birds which disappeared in prehistoric and early historic times, usually due to human activity (i.e., starting with the Upper Paleolithic Revolution). For birds having gone extinct in modern times (since 1500), see List of extinct birds.

Close to nature forestry

Close to nature forestry is a management approach treating forest as an ecological system performing multiple functions. Close to nature silviculture tries to achieve the management objectives with minimum necessary human intervention aimed at accelerating the processes that nature would do by itself more slowly. It works with natural populations of trees, ongoing processes and existing structures using cognitive approach, as in the case of uneven-aged forest (Plenterwald). Its theory and practice takes forest as a self regulating ecosystem and manages it as such.

It aims at overcoming the divorce between forestalist and ecologist management systems of forest. As an important consequence, it concludes that if properly applied, it would render the segregation of forest lands into "productive" and "reserves" or national parks unnecessary.

Columbian exchange

The Columbian exchange, also known as the Columbian interchange, named for Christopher Columbus, was the widespread transfer of plants, animals, culture, human populations, technology, diseases, and ideas between the Americas, West Africa, and the Old World in the 15th and 16th centuries. It also relates to European colonization and trade following Christopher Columbus's 1492 voyage. Invasive species, including communicable diseases, were a byproduct of the Exchange. The changes in agriculture significantly altered and changed global populations. The most significant immediate impact of the Columbian exchange was the cultural exchanges and the transfer of people (both free and enslaved) between continents.

The new contact between the global population circulated a wide variety of crops and livestock, which supported increases in population in both hemispheres, although diseases initially caused precipitous declines in the numbers of indigenous peoples of the Americas. Traders returned to Europe with maize, potatoes, and tomatoes, which became very important crops in Europe by the 18th century.

The term was first used in 1972 by American historian Alfred W. Crosby in his environmental history book The Columbian Exchange. It was rapidly adopted by other historians and journalists and has become widely known.

Erskine River

The Erskine River is a river in southwestern Victoria, Australia. It arises in the Otway Ranges and enters Bass Strait to the east of Cape Otway through the town of Lorne. The Erskine River above the falls is known for its high diversity of native fish species and low occurrence of introduced species.

Feral parakeets in Great Britain

Feral parakeets in Great Britain are feral parakeets that are an introduced species into Great Britain. The population consists of rose-ringed parakeets (Psittacula krameri), a non-migratory species of bird that is native to Africa and the Indian Subcontinent. The origins of these birds are subject to speculation, but they are generally thought to have bred from birds that escaped from captivity.

The British parakeet population is mostly concentrated in suburban areas of London and the Home Counties of South-East England, and for this reason the birds are sometimes known as "Kingston parakeets" or "Twickenham parakeets", after the London suburbs of Kingston upon Thames and Twickenham. The parakeets, which breed rapidly, have since spread beyond these areas, and flocks have been sighted in other parts of Britain. There is a flock of around 20 to 30 settled in Victoria Park, Glasgow. Other separate parakeet populations exist around other European cities.

Hypothetical species

Several extinct species have been postulated, but owing to a lack of evidence they can only be regarded as hypothetical extinct species. They have caused confusion, as they may have been a separate species, a subspecies, or an introduced species.

Indian palm squirrel

The Indian palm squirrel or three-striped palm squirrel (Funambulus palmarum) is a species of rodent in the family Sciuridae found naturally in India (south of the Vindhyas) and Sri Lanka. In the late 19th century, the palm squirrel was introduced to Madagascar, Réunion, Mayotte, Comoro Islands, Mauritius, Seychelles and Australia, where it has since become a minor pest. The closely related five-striped palm squirrel, F. pennantii, is found in northern India, and its range partly overlaps with this species.

Indigenous (ecology)

In biogeography, a species is indigenous to a given region or ecosystem if its presence in that region is the result of only natural processes, with no human intervention. The term is equivalent to the concept of native or autochthonous species. Every wild organism (as opposed to a domesticated organism) has its own natural range of distribution in which it is regarded as indigenous. Outside this native range, a species may be introduced by human activity, either intentionally or unintentionally; it is then referred to as an introduced species within the regions where it was anthropogenically introduced.The notion of indigeneity is often a blurred concept, as is a function of both time and political boundaries. Seen over long periods of time, plants and animals take part in the constant movement of tectonic plates—species appear and may flourish, endure, or become extinct, and their distribution is rarely static or confined to a particular geographic location.

An indigenous species in a location is not necessarily also endemic to that location. Endemic species are exclusively found in a particular place. An indigenous species may occur in areas other than the one under consideration. The terms endemic and indigenous also do not imply that an organism necessarily first originated or evolved where it is currently found.

Invasion (disambiguation)

An invasion is a military action of soldiers entering a foreign land.

Invasion or invader may also refer to any act of "going into"

In archaeology, of prehistoric cultures, see Migrations and invasions in archaeology

In surgery, the breaching of the skin barrier; see Invasiveness of surgical procedures

Invasion (cancer), the spread of cancer to surrounding tissues

Home invasion, a crime similar to burglary

Invasive species, an introduced species that has spread widely

Introduced species, a widespread introduced species

Infestation of pests (insects, spiders, etc.), in an undesired location

Alien invasion, an imaginary or theoretical invasion by extraterrestrials

Invasive species

An invasive species is a species that is not native to a specific location (an introduced species), and that has a tendency to spread to a degree believed to cause damage to the environment, human economy or human health.The criteria for invasive species has been controversial, as widely divergent perceptions exist among researchers as well as concerns with the subjectivity of the term "invasive". Several alternate usages of the term have been proposed. The term as most often used applies to introduced species (also called "non-indigenous" or "non-native") that adversely affect the habitats and bioregions they invade economically, environmentally, or ecologically. Such invasive species may be either plants or animals and may disrupt by dominating a region, wilderness areas, particular habitats, or wildland–urban interface land from loss of natural controls (such as predators or herbivores). This includes non-native invasive plant species labeled as exotic pest plants and invasive exotics growing in native plant communities. It has been used in this sense by government organizations as well as conservation groups such as the International Union for Conservation of Nature (IUCN) and the California Native Plant Society. The European Union defines "Invasive Alien Species" as those that are, firstly, outside their natural distribution area, and secondly, threaten biological diversity.The term is also used by land managers, botanists, researchers, horticulturalists, conservationists, and the public for noxious weeds. The kudzu vine (Pueraria lobata), Andean pampas grass (Cortaderia jubata), and yellow starthistle (Centaurea solstitialis) are examples. An alternate usage broadens the term to include indigenous or "native" species along with non-native species, that have colonized natural areas (p. 136). Deer are an example, considered to be overpopulating their native zones and adjacent suburban gardens, by some in the Northeastern and Pacific Coast regions of the United States. Sometimes the term is used to describe a non-native or introduced species that has become widespread (p. 136). However, not every introduced species has adverse effects on the environment. A nonadverse example is the common goldfish (Carassius auratus), which is found throughout the United States, but rarely achieves high densities (p. 136). Notable examples of invasive species include European rabbits, grey squirrels, domestic cats, carp and ferrets. It has been suggested that genetically modified organisms (GMOs) as a class should be regarded and managed as invasive species.Dispersal and subsequent proliferation of species is not solely an anthropogenic phenomenon. There are many mechanisms by which species from all Kingdoms have been able to travel across continents in short periods of time such as via floating rafts, or on wind currents. Charles Darwin, a British naturalist, performed many experiments to better understand long distance seed dispersal, and was able to germinate seeds from insect frass, faeces of waterfowl, dirt clods on the feet of birds, all of which may have traveled significant distances under their own power, or be blown off course by thousands of miles.

Invasion of long-established ecosystems by organisms from distant bio-regions is a natural phenomenon, which has likely been accelerated via hominid-assisted migration although this has not been adequately directly measured.

The definition of "native" is controversial in that there is no way to precisely determine nativity. For example, the ancestors of Equus ferus (modern horses) evolved in North America and radiated to Eurasia before becoming locally extinct. Upon returning to North America in 1493 during their hominid-assisted migration, it is debatable as to whether they were native or exotic to the continent of their evolutionary ancestors.

Invasive species in New Zealand

A number of introduced species, some of which have become invasive species, have been added to New Zealand's native flora and fauna. Both deliberate and accidental introductions have been made from the time of the first human settlement, with several waves of Polynesian people at some time before the year 1300, followed by Europeans after 1769.Almost without exception, the introduced species have been detrimental to the native flora and fauna but some, such as farmed sheep and cows and the clover upon which they feed, now form a large part of the economy of New Zealand. Registers, lists and indexes of species that are invasive, potentially invasive, or a threat to agriculture or biodiversity are maintained by Biosecurity New Zealand.

Island restoration

The ecological restoration of islands, or island restoration, is the application of the principles of ecological restoration to islands and island groups. Islands, due to their isolation, are home to many of the world's endemic species, as well as important breeding grounds for seabirds and some marine mammals. Their ecosystems are also very vulnerable to human disturbance and particularly to introduced species, due to their small size. Island groups such as New Zealand and Hawaii have undergone substantial extinctions and losses of habitat. Since the 1950s several organisations and government agencies around the world have worked to restore islands to their original states; New Zealand has used them to hold natural populations of species that would otherwise be unable to survive in the wild. The principal components of island restoration are the removal of introduced species and the reintroduction of native species.

List of reptiles of Great Britain

Ten or eleven species of reptiles occur in Great Britain: three snakes and three lizards, which were established at the time of the last ice age. Additionally, Britain has a number of introduced species which have become naturalized in their new environments such as tortoises.

Sea turtles have been recorded as coastal vagrants and the red-eared terrapin occurs as an introduced species.

Lists of invasive species

These are lists of invasive species by country or region. A species is regarded as invasive if it has been introduced by human action to a location, area, or region where it did not previously occur naturally (i.e., is not a native species), becomes capable of establishing a breeding population in the new location without further intervention by humans, and becomes a pest in the new location, threatening agriculture and/or the local biodiversity.

The term invasive species refers to a subset of those species defined as introduced species, for which see List of introduced species.

List of invasive species in Africa

List of invasive species in South Africa

List of invasive plant species in South AfricaList of invasive species in Asia

Invasive species in JapanList of invasive species in Australasia

List of invasive species in Australia

Invasive species in New ZealandList of invasive species in Europe

Invasive species in the British Isles

List of invasive species in Italy

List of invasive species in PortugalList of invasive species in North America

Invasive grasses of North America

Invasive species in the United States

List of invasive species in California

List of invasive plant species in California

List of invasive species in Florida

List of invasive species in the Everglades

List of invasive marine fish in Florida

List of invasive plant species in Florida

List of invasive plant species in Arizona

List of invasive plant species in the Indiana Dunes

List of invasive plant species in Maryland

List of invasive plant species in Nevada

List of invasive plant species in New Jersey

List of invasive plant species in New Mexico

List of invasive plant species in Utah

List of invasive plant species in West Virginia

List of invasive plant species in Wisconsin

Invasive species in Hawaii

List of bird species introduced to the Hawaiian Islands

List of invasive plant species in HawaiiInvasive species in South America

List of invasive species in Colombia

Naturalisation (biology)

In biology, naturalisation (or naturalization) is any process by which a non-native organism or species spreads into the wild and its reproduction is sufficient to maintain its population. Such populations are said to be naturalised.

Some populations do not sustain themselves reproductively, but exist because of continued influx from elsewhere. Such a non-sustaining population, or the individuals within it, are said to be adventive. Cultivated plants are a major source of adventive populations.

Naturalised species may become invasive species if they become sufficiently abundant to have an adverse effect on native plants and animals.

Satellite Island (Tasmania)

Satellite Island is a small island, part of the Partridge Island Group, lying close to the south-eastern coast of Tasmania, in the D'Entrecasteaux Channel between Bruny Island and the Tasmanian mainland. It is surrounded by an ancient fossil clad rock shelf, home to an array of local shellfish, including crayfish, native scallops, abalone and oysters. Satellite Island was discovered in 1792 by the French expedition led by Bruni D'Entrecasteaux. It was originally used as an observatory for the night sky.Satellite Island has a variety of native bird life including a resident pair of rare white-breasted sea eagles and the red breasted robin. The island is encircled by a variety of native scrub and trees including ancient blue gums and some introduced species.

The Island is privately owned and can be hired for exclusive use. It was ranked #2 by Harper's Bazaar UK on their list of the world's best private islands.

White-faced whistling duck

The white-faced whistling duck (Dendrocygna viduata) is a whistling duck that breeds in sub-Saharan Africa and much of South America.

This species is gregarious, and at favoured sites, the flocks of a thousand or more birds arriving at dawn are an impressive sight. As the name implies, these are noisy birds with a clear three-note whistling call.


A wildflower (or wild flower) is a flower that grows in the wild, meaning it was not intentionally seeded or planted. Yet "wildflower" meadows of a few mixed species are sold in seed packets. The term implies that the plant probably is neither a hybrid nor a selected cultivar that is in any way different from the way it appears in the wild as a native plant, even if it is growing where it would not naturally. The term can refer to the flowering plant as a whole, even when not in bloom, and not just the flower."Wildflower" is not an exact term. Terms like native species (naturally occurring in the area, see flora), exotic or, better, introduced species (not naturally occurring in the area), of which some are labelled invasive species (that out-compete other plants – whether native or not), imported (introduced to an area whether deliberately or accidentally) and naturalized (introduced to an area, but now considered by the public as native) are much more accurate.

In the United Kingdom, the organisation Plantlife International instituted the "County Flowers scheme" in 2002, for which members of the public nominated and voted for a wild flower emblem for their county. The aim was to spread awareness of the heritage of native species and about the need for conservation, as some of these species are endangered. For example, Somerset has adopted the Cheddar Pink (Dianthus gratianopolitanus), London the Rosebay Willowherb (Chamerion angustifolium) and Denbighshire/Sir Ddinbych in Wales the rare Limestone Woundwort (Stachys alpina).


Wildlife traditionally refers to undomesticated animal species, but has come to include all organisms that grow or live wild in an area without being introduced by humans. Wildlife can be found in all ecosystems. Deserts, forests, rain forests, plains, grasslands and other areas including the most developed urban areas, all have distinct forms of wildlife. While the term in popular culture usually refers to animals that are untouched by human factors, most scientists agree that much wildlife is affected by human activities.Humans have historically tended to separate civilization from wildlife in a number of ways including the legal, social, and moral sense. Some animals, however, have adapted to suburban environments. This includes such animals as domesticated cats, dogs, mice, and gerbils. Some religions declare certain animals to be sacred, and in modern times concern for the natural environment has provoked activists to protest against the exploitation of wildlife for human benefit or entertainment.

The global wildlife population decreased by 52 percent between 1970 and 2014, according to a report by the World Wildlife Fund.

Food webs
Example webs
Ecology: Modelling ecosystems: Other components

This page is based on a Wikipedia article written by authors (here).
Text is available under the CC BY-SA 3.0 license; additional terms may apply.
Images, videos and audio are available under their respective licenses.