Collectively, non-native crops and livestock account for 98% of US food. [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]. Numerous fish and game animals have been introduced for the purposes of sport fishing and hunting. 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. September 16, 2003.
In Alaska, foxes were introduced to many islands to create new populations for the fur trade. 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. 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. Other non-natives with positive benefits include honeybees, plants that feed butterflies,… For life on planets other than Earth, see, Terminology: introduced species and subsets, Motivations for intentional introductions, U.S. Environmental Protection Agency. Clemson University – DPI. 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]. Some of these species have escaped horticultural control and become invasive. 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). [20] However the small percentage of introduced species that become invasive can produce profound ecological changes.
Invasive species can have varied effects on native species, the surrounding ecosystem, and the economy.
These examples represent only a small subsample of species that have been moved by humans for economic interests. Others may become feral, but do not seriously compete with natives, but simply increase the biodiversity of the area. 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]. However, invasive species can impact other species through hybridization, and can alter ecosystem services, including nutrient cycling and water filtration. 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. 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]. 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. 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. An invasive species is an organism that is not indigenous, or native, to a particular area. Web site at. Invasive species can cause great economic and environmental harm to the new area. Since then, it has thrived on prey unequipped to deal with its speed, nearly leading to the local extinction of a variety of species. The impacts of introducing a non-native or invasive species to an ecosystem will vary depending on a number of factors.. [22][23] This species has become invasive in Australia, where it threatens native rare plants and causes erosion and soil slumping around river banks. The invasive species may provide little to no food value for wildlife. Unintentional introductions occur when species are transported by human vectors. [31], 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. Non-native species can have various effects on the local ecosystem. Introduced species that become established and spread beyond the place of introduction are considered "naturalized". Many non-native plants have been introduced into new territories, initially as either ornamental plants or for erosion control, stock feed, or forestry. Species that humans intentionally transport to new regions can subsequently become successfully established in two ways. University of Texas at Austin, Austin, Texas, USA. 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. [11] These and other benefits from non-natives are so vast that, according to the Congressional Research Service, they probably exceed the costs.[12]. 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. Kennedy, K. 1992. Squash (pumpkins), maize (corn), and tobacco are native to the Americas, but were introduced to the Old World. Other examples of species introduced for the purposes of benefiting agriculture, aquaculture or other economic activities are widespread. 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. If there is no ecological niche for the species to fill or the species cannot adapt to fill a different ecological niche, the species will likely go extinct relatively quickly at the local level. A systematic study of the genus Phyla Lour (Verbenaceae: Verbenoideae, Lantanae). Economic: Perhaps the most common motivation for introducing a species into a new place is that of economic gain. 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. In the northeastern USA, the dominant earthworms arose from non-native species in the nineteenth century; they have enriched the soil. Livre Rouge de la flore menacée de France.Tome I. Espèces prioritaires. 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. This was seen in the introduction of guppies in Trinidad to encourage population growth and introduce new alleles into the population. Introductions have also been important in supporting recreation activities or otherwise increasing human enjoyment. The insect commonly known as the brown marmorated stink bug (Halyomorpha halys) was introduced accidentally in Pennsylvania. Intentional introductions have also been undertaken with the aim of ameliorating environmental problems. He deliberately released eighty starlings into Central Park in New York City in 1890, and another forty in 1891. The timber industry promoted the introduction of Monterey pine (Pinus radiata) from California to Australia and New Zealand as a commercial timber crop. The transition from introduction, to establishment and to invasion has been described in the context of plants. 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. Non-native species can have various effects on the local ecosystem. Introduced species. [6] Introduced species are essentially "non-native" species. It is a source of resveratrol, a dietary supplement. Over 200 species have been introduced to the San Francisco Bay in this manner making it the most heavily invaded estuary in the world. By definition, a species is considered "introduced" when its transport into an area outside of its native range is human mediated. 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. Thomas Austin, a British landowner had rabbits released on his estate in Victoria because he missed hunting them. In the second case, species intentionally transported into a new region may escape from captive or cultivated populations and subsequently establish independent breeding populations. Olivier, L., J. P. Galland, and H. Maurin, editors.1995. 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. 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. Most introduced species do not become invasive. 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. [13] Eurasian carp was first introduced to the United States as a potential food source. Invasive species can change the food web in an ecosystem by destroying or replacing native food sources. 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. By 1997, it had covered some 50 km2.
With respect to plants, these latter are in this case defined as either ornamental or cultivated plants. The term "invasive" is used to describe introduced species when the introduced species causes substantial damage to the area in which it was introduced. When a new species is introduced, the species could potentially breed with members of native species, producing hybrids. 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]. 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.