Talk:Introduced species

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An Australian Ecologist's Point of View[edit]

(From someone not used to this very interesting concept and environment that is Wikipedia.)

As an ecologist, I have a real problem with this page.

This page makes it sound like the introduction of exotic species is no big deal, that it's OK, and rarely has impacts.

To be very polite, this is rubbish.

I hail from Australia, where almost all our classes of wildlife, from native freshwater fish to birds to marsupials, have been seriously stuffed by introduced species. It's heartbreaking, the mess of what was an amazing and unique flora and fauna Australian ecologists and naturalists face every day. At the moment we have an ecological disaster of unimaginable proportions unfolding as a stupidly introduced species, the Cane Toad, invades the relatively pristine ecosystems of the Northern Territory including Kakadu National Park.

People should get a few things very clear.

1) ALL introduced species have impacts. Many - a majority perhaps - have quite serious impacts. This is the case at least in countries with highly endemic, specialised and isolated floras and faunas like Australia.

2) It is not fair to unleash exotics species on endemic species. Those exotic organisms may be predators and/or have features due to their evolutionary environment that makes them very competitive, and similarly makes endemic species very defenceless and/or uncompetitive against these exotic species.

The rich diversity of unique species across many parts of the world exist only because they a separated by barriers - particularly seas and oceans - from other species of other land masses, particularly the "super-species" (see below). Barriers that could never be crossed, unless millions of years in the future through continental drift. Barriers that could not be broken until humans beings invented ships then planes.

3) As a consequence of the above if you unleashed most of the species of world against eachother by willy-nilly introductions, only a very few, usually highly fecund, ultra-competitive generalist "super-species" would survive.

4) And this is the big one. HUMAN BEINGS INTRODUCING EXOTIC ORGANISMS IS THE BIGGEST THREAT TO BIODIVERSITY OF THE WORLD ALONG WITH HABITAT DESTRUCTION. Yes, that is right. AND WHAT PEOPLE DON'T UNDERSTAND IS THAT IF CONTINUE TO PLAY THIS STUPID GAME OF INTRODUCING EXOTIC ORGANISMS WE WILL LOSE MOST ENDEMIC ORGANISMS, INCLUDING THE ONES WE TREASURE FOR BEING SO UNIQUE, SO BEAUTIFUL, SO THIS, SO THAT.. We will lose all the unique species, and will end up in boring homogenous world dominated by the same handful of "super-species" - cockroaches, mice, rats, argentine ants, indian mynahs, cane toads, dandelions, thistles, etc.

These are difficult ideas to convey but I hope people can understand what I'm saying here.

But this "oh yeah, introducing species doesn't really matter" attitude has to go.


Hi Simon,

dont know when you posted this..anyway, i just answer... sorry for that

(1): no..most instrduced species dont even survive long enough to be noticed...

(2): what's fair then? a species that evolved in an environment for millions of years should be by far better prepared for that special environment than any exotic species, shouldn't it? or did they miss something? aren't they about to be extiguished then in any case?

(3) super-species? what should that be? rats? mice? pidgeons? crap! maybe humans... ;-)

(4) we will continue, and the world will survive... and, yes, the world will change, and it changed already...surprise... biodiversity? well, the world has to adopt to a very dominant species... we are some kind of dominant on this planet... will it lead to more or less biodiversity? well...difficult to say... there are more species living here in europe than before humans, because of humans(exotic birds, fish, reptiles etc.)... there is a threat to some species because of humans.. but.. introducing humans in australia is invasive in itself... think about it! we cannot substract ourselves from this planet, and, when it comes to me, i dont want to :-) we are the only species that (sometimes) thinks about such issues... we select and we distribute other species, if we like it or not... so far (about 500 years) we, of course cause some damage to a lot of species, but, after all... it is just us that lost the joy of variety, the nature itself does not really care. so people that dont treasure it, that dont even see, it wont miss a thing.

Therefore, i think you fight a kinda lost battle (talk) 02:22, 29 January 2009 (UTC)

Not sure if this is the forum to be getting in to this, but you are making some very spurious claims based on faux-science:
To say that a species will outlive an invader due to the fact that it has had years to adapt to the environment is missing the point entirely. Ecosystems have adapted to states over billions of years, they have done so that they exist in a balance. Introducing invader species harms indig. species usually because they have no natural enemies - they are therefore free to reproduce without hinderance. Without competition, the species are then able to colonise vast swathes of areas and choke out the indigenous plants or animals.
Now, the point has been raised whether or not this really is that bad, nature is nature, after all, and we have had species get wiped out over the billions of years of evolution anyway.
The crucial point is that nature is robust merely through its diversity. It is the very depth of species that has enable nature to continue as it has. If there were only one type of tree, for example (an extreme hypothesis), and a fungus developed that attacked that species, the entire planet's tree population would be under threat. With multiple tree species, the situation is quite different: at the very worst, only one species will be wiped out, but even that is unlikely, because the trees would naturally be found so far apart that the rot would struggle to spread as fast or as wide as it would otherwise: resistant species would block its way.
This of course does not even touch on the matter of the potential discoveries that the human race has lost by way of species extinction. Because plants are unable to run away or attack predators or move about, many of them have developed complex chemicals within their systems in order to defend themselves, or maximise their use of sunlight, etc. These chemicals are often of amazing use to use. The cure for AIDS, cancers even the common cold could be locked away in some innocuous shrub somewhere. Of course, it could also have been lost forever because that same shrub was destroyed by a lack of nitrogen in the soil, due to some invader species of plant multiplying unfettered and leaching more of the element out of the soil than the other plants in the area had been adapted to replace. (talk) 15:13, 28 October 2010 (UTC)

Introduced vs Invasive[edit]

This item drips with ideological prejudice. If we were talking about human beings African Americans would be termed "introduced species" and would be considered "invasive". In fact white Europeans would be considered introduced and invasive and that probably would be something this author(s) would agree with. In evolutionary terms the issue is not whether humans brought a species to a specific area vs. wind or birds, but whether that species can survive in Darwinian terms. By strict Darwinism if the organism can survive it is automatically in harmony with natural law. In fact, Darwin aside, the natural world is strengthened by the free mixing of ALL its elements, not just the ones humans consider "native". There is nothing intrinsically good about being "native". What was native 10,000 years ago may not even be alive anymore because it was replaced by an organism that is superior is some respect. Should we try to resurrect that weak species because it was "native"? And where do we draw our time lines? Should native be the world of 1,000 years ago? 10,000 years ago? A million years ago? Much of so-called environmental thinking is really arrogant hubris by people who are very good at propounding self-righteous negativity and very poor at envisioning and creating the positive. This wiki entry is an example. All that being said Darwin is a hard master and I would prefer a world that includes more than kudzu and green algae. But we must recognize that human manipulation of the environment can, and on balance arguably is, is a good thing. You don't eliminate cancer by destroying the host. This presupposes that the humans have motivations beyond greed and an MBA. Otherwise Darwin will consider us "invasive" and create conditions where we can't survive. There is some evidence that is already happening. However I believe we will adapt and adaptation is the correctional mechanism that eventually deals with any side effects of truly "invasive" I.E. damaging introduced species. If the snakes take over the island eventually there will come a raptor that loves filet of rattlesnake. —Preceding unsigned comment added by (talk) 18:04, 15 February 2009 (UTC)

Suggest merging with Invasive species; but having the contents here, as "introduced" is passive whereas "invasive" implys active invasion, which is not the case. Andy Mabbett 17:09, 9 Dec 2003 (UTC)

makes sense, although it will need bit of a rejig. Jim
I disagree. Most introduced species are quite benign. Invasive species are those that are serious pests or disruptions to the ecosystem - quite a different thing. I'll not put it back without more discussion, but I think the concepts are sufficiently different to merit separate pages. BTW "invasive" is an accepted term; this is not a POV thing. Millions of dollars are spent each year dealing with invasive species. Pollinator 04:52, 10 Dec 2003 (UTC)
would an alternative/additional idea be to have the conceptual content in one article and the list in another? I agree that "introduced" is better (more NPOV!) than "invasive", anyway. I'll do a search for unlinked occurrences of the phrase and add some links sometime. seglea 21:55, 9 Dec 2003 (UTC)

Hang on! we're cutting across each other. I'll go and do something else for a while and let you finish what you're doing. seglea 22:36, 9 Dec 2003 (UTC)

The more I think about this, the more I think it's a mistake. If you look at your garden, I betcha 80% of the species are "introduced." However, let me send you some kudzu seeds, so you will see what "invasive" really means! They are NOT the same thing.
I would agree. Introduced and invasive are not the same thing. Many species when introduced will spread very slowly if at all, and may not affect the ecosystem greatly. A very few species are incredibly successful at spreading through new territory (e.g. kudzu). WormRunner 05:58, 10 Dec 2003 (UTC)
I also agree, for what it's worth. As "introduced species" is a blanket term covering both invasives and non-invasives, this article's terminology and intro need a bit of a retouch, I think. There needs to be a more expasses pooplicit distinction between the two "types" of exotics. As it stands the article gives the impression that all introduced species are harmful. But as long as the difference is clearly explained, I think both invasives and non-invasives can be discussed in the same conceptual article. After all, there's already a section on reintroduction.
The list should be kept separate as I believe an extensive list is of value. The list article should also contain a note differentiating the possible meanings behind "introduced species." Just my opinion- Hadal 06:53, 10 Dec 2003 (UTC)
We need to better define the terms, and perhaps redistribute the sections. In my mind "introduced species" and "invasive species" are NOT the same thing, although there is a movement in some places to simply lump them together, the idea being that "invasive" is a loaded word (therefore POV I guess). I think they can be distinguished and separate articles preparted for each. I will research/work on definitions as a point of departure for possibly restoring Invasive species - Marshman 17:34, 9 Jan 2004 (UTC)
Cultivated plants can be native or introduced. The introduced cultivated plants are not usually invasive, though kudzu comes to mind as a notable exception. Pollinator 19:38, 9 Jan 2004 (UTC)
Much as I would like to agree with you (and have included that concept in my rewrite), most definitions of "introduced species" that I could find exclude cultivated species by including the fact that a species is technically introduced only if it is also capable of propagating on its own in the wild. - Marshman 22:53, 9 Jan 2004 (UTC)
Exclusion of cultivated species from definition as 'introduced' is certainly not normal in Britain or other European countries; e.g. "Giant Sequoia was introduced to Britain in 1853" contains no suggestion of any need for naturalisation to be occurring (neither has the species shown any sign of doing so). All 'introduced' indicates is that the species is not native. - MPF 15:35, 25 Feb 2005 (UTC)

I am unaware of usage excluding cultivated plants from "introductions" - in fact, if you read the history of spread of cultivated species you see the term "introduced" repeatedly. As I know it (mostly based on used I have encountered in floras), introduced species can be:

  • cultivated
  • persistent after cultivation
  • naturalised
  • invasive

Guettarda 16:13, 25 Feb 2005 (UTC)

Invasive species are always introduced, but introduced species are rarely invasive[edit]

For what it's worth, I agree with the thoughts express recently by Pollinator, WormRunner, and Hadal. All invasive species are introduced, but not all introduced species are invasive; thus, the term introduced is not at all synonymous with invasive. An invasive species is simply an introduced species that has shown the ability to cause economic and ecological damage in its new environment. A very small percentage of introduced species ever reach the point that they could be considered invasive (i.e., damaging). The development and maintenance of domesticated plants (crops) and animals under the care of humans is largely unrelated to the establishment of introduced populations capable of sustaining and replacing themselves in a natural situation without the aid of humans. That's not to say that domesticated animals don't sometimes escape to the wild and establish self-sustaining populations (examples include wild horses in western U.S., red junglefowl [=chickens] in Hawaiian Islands, mute swans in eastern U.S., rock pigeons worldwide). Rather than clarifying the clear distinctions that most ecologists have long recognized between introduced and invasive species, I fear that Marshman's rewrite of the introductory paragraphs has simply muddied the waters further. In my opinion, there's definitely a need to retain a separate Invasive species page. John Trapp 20:11, 9 Jan 2004 (UTC)

I think you should reread my changes. I agree almost completely with what you are saying and would next propose that we reinstate the Invasive species article. However, I do think you have overstated the clarity of the most important point: whether a species is invasive or not (as opposed to just introduced, about which there is little to argue, except whether farm animals are or are not "introduced") is not so easy to judge since there must be agreement of harm. In Hawaii, better than 90% of all the lowland vegetation is non-native, and it is really a matter of serious debate whether all of these species have caused harm (most visitors and residents alike think the vegetation is beautiful; environmentalists, botanists, many native Hawaiians regard the vegetation as invasive without question). Because of the strong potential for disagreement, there is generally a movement (in the US if not worldwide) to define all as simply "introduced" and dump the word "invasive". I am proposing that "invasive" be all that you say it is, but include the regulatory component. Presumably, species listed by government agencies (or even NGOs) have been deemed to be officially harmful somewhere. This removes POV arguements that are likely to ensue. Further, it is consistent with sources of definitions, going against which would be to "muddy the waters" - Marshman 22:33, 9 Jan 2004 (UTC)

The great majority of introductions have involved the transfer of European species to New World and Australasian countries by settlers; in some countries, Acclimatization Societies were set up, particularly in the late nineteenth century, to promote this process. However there have also been introductions between New World countries, and of New World species to Old World countries.

May we have source for this affirmation please ?

If I dare, that sounds to me like...a bit new world perspective. It is perhaps forgetting all the big travels made by navigators, who brought back many new species to Europe.


Are you familiar with black locust, Robina pseudoacacia, an Appalachian tree that was introduced to France? It is the source of the famous French "acacia" honey. I expect it is naturalized, comment? 15:37, 10 Jan 2004 (UTC) Pollinator 17:59, 10 Jan 2004 (UTC)
terrible to discuss when watchlists are off. No, do not know it, but will ask to one of our french, who is spending all his time on the vegetal species articles. PomPom

w:fr:Jeffdelonge made it today :-) w:fr:Robinier. What does that exactly mean "naturalized" ? All I can say is that acacia honey is among the most consummed, and very appreciated. That little tree made it about in most of the country. Mostly west, but we find many around as well. In the west, it is often associated with sandy soils in particular. It does not go further north than our country. I think in some places it spreaded a lot, but we would not qualify it an invasive species :-) Apparently, it is very well adapted to our mild climate.
The term "naturalized" means that after an initial introduction, the species is able to spread on its own - Marshman 01:46, 17 Jan 2004 (UTC)

I also doubt the correctness of this statement and will remove it. Let us not forget the numerous species introduced from Asia to Europe in ancient times, including most cereal species, several herbs and spices, rhubarb and others. Let us not forget species introduced from the New World to the Old, including potatoes, tomatoes, maize, the rainbow trout, the raccoon and many others. Until someone can back it up with numbers, this sentence should disappear. Burschik 11:05, 27 Jul 2004 (UTC)

Yesterday, I saw a documentary about introduced species on TV. They claimed that there were more than 1400 introduced animal species in Germany alone. Burschik 09:21, 28 Jul 2004 (UTC)

Introduced plants[edit]

Algae are not plants; reference to Caulerpa as a plant is not strictly accurate even though common usage often lumps algae in with plants. Is it more important to maintain "familiar" usage for non-technical readers, or strict accuracy? Guettarda 23:52, 9 Dec 2004 (UTC)

Moved from article[edit]

User:Codman inserted a lengthy piece to the article. Not only does it not adhere to the Manual of Style (since it is attempts to convince one of a certain point of view), it also amounts to original research since it re-defines introduced species away from standard usage. I have tried discussing this with the user on his talk page, but he seems unable to grasp that editors cannot re-define terms to meet their own interpretations.

A long term ecological perspective on global biodiversity and the threat that introduced species pose to it.[edit]

It is common for laypeople without training or knowledge in ecological science to defend the introduction of exotic organisms. Very often these people have a vested interested in the introduction of an exotic organism, be it the fly fishermen in Australia who enjoys fishing for introduced Trout or the gardener in the USA who delights in the latest exotic garden plant.

Some, such as the Australian fly-fisher above, may even justify the wholesale introduction of exotic organisms and issue pseudo-scientific arguments about how introduced species cannot have catastrophic impacts, that "Nature always balances itself", etc.

These attitudes are dangerous, these arguments simply fallacious, with the weight of a thousand tragic ecological events, from the introduction of Nile Perch in Lake Victoria to the Cane Toad in the Tropics of Australia weighing against them, and demonstrating clearly that nature cannot "balance itself" when humans introduce exotic organisms to ecosystems and species that have evolved without those exotic organisms.

4 main points should be considered:

1) ALL introduced species that establish self-sustaining populations in countries/landmasses in which they have been introduced have negative impacts on endemic species. In countries/landmasses with highly endemic, specialised and isolated floras and faunas such as Australia, New Zealand, Madagascar, the Galapogos Islands, etc many of the introduced species that establish themselves have very serious negative impacts on endemic species

2) It is not realistic for humans to unleash exotics species on endemic species that have not evolved to cope with the exotic species being introduced and then expect all endemic species to survive. Those exotic organisms may be predators and/or have features due to their evolutionary environment that makes them very competitive, and similarly makes endemic species very defenceless and/or uncompetitive against these exotic species.

The rich diversity of unique species across many parts of the world that we treasure exist only because they a separated by barriers - particularly seas and oceans - from other species of other land masses, particularly the "super-species" (see below). These are barriers that could never be crossed, except for many millions of years in the future through continental drift. These are barriers that could not be broken until humans beings invented ships then planes. Now human beings have the power to bring into contact species that would never encountered each other in the history of their existences, and to do it with ease in weeks, days or even just hours.

3) As a consequence of the above if human beings gradually unleash most of the species of the world against each other by foolhardy introductions - species that otherwise would never have encountered each other - only a very few, usually highly fecund, ultra-competitive generalist "super-species" would survive.

4) As a further consequence of the above, humans introducing exotic organisms is the biggest threat to biodiversity of the world along with habitat destruction. What lay people do not understand is that if humans continue to introduce exotic organisms we will lose most endemic organisms, including the ones humans treasure for being so unique, so beautiful, etc... The world, and the human race, will lose most of the unique species, and will end up in boring homogenous world dominated by the same handful of "super-species" - cockroaches, mice, rats, argentine ants, indian mynahs, cane toads, dandelions, thistles, etc.

The introduction of exotic organisms by humans should be recognised for what it is ultimately - a threat to endemic organisms around the world and a threat to global biodiversity.


James E. Byers, Sarah Reichard, John M. Randall, Ingrid M. Parker, Carey S. Smith, W. M. Lonsdale, I. A. E. Atkinson, T. R. Seastedt, Mark Williamson, E. Chornesky, D. Hayes. 2002. Directing Research to Reduce the Impacts of Nonindigenous Species. Conservation Biology 16(3):630-640

For biological invasions these stages may include (1) arrival (risk analysis of pathways), (2) establishment (risk of the organism forming viable, reproducing populations), (3) spread (risk of the organism expanding its extent), and (4) impact (risk the species having a measurable effect on existing species or communities). The "tens rule" (Williamson 1996) estimates that 10% (between 5% and 20%) of imported species will make the transition from one stage to the next.

Thus, existing scientific usage does not agree with the assertion that all introduced species have impacts on endemic species. Guettarda 03:07, 15 September 2005 (UTC)

Thanks Guettarda, I was getting ready to do the same. User:Codman seems to confuse introduced species with Invasive species. Some of the ideas he expressed could be placed there, if the soapbox tone is removed, and they comments are referenced. There are many other nuances. Pollinator 04:57, 15 September 2005 (UTC)

I'm totally over the semantic "introduced species" vs "invasive species" issue. Clearly, I am only talking about introduced species that establish breeding populations in the wild in the countries of introduction. Why would I be talking about introduced species whose introductions have failed??? And this bloody tens rule. Clearly I'm talking about introduced species that establish, so we can finally forget about Williams and his tens rule (which, no doubt, was not based on an examination of the Australian situation).

Still, if you are really into this division, then fine, move my article to "invasive species" and I'd appreciate.

Because, I don't appreciate having my carefully worked on addition moved. Don't quote your Northern Hemisphere/Europe/US-centric work on how "most introduced species don't have an impact" to me!!! Get out of your zone and see what the hell introduced species are doing outside of these landmasses! See what the hell introduced species are doing in Australia and elsewhere.

So now end up with an ambivalent article again which really does make the average person think it's quite OK to introduce exotic species for whatever reason.

This is a disgrace for Wikipedia. And if you guys claim to be ecologists, I am disappointed. There are plenty of ecologists and evolutionary biologists who CAN see the big picture and CAN see what a threat introduced species pose to endemic organisms (and thus biodiversity) everywhere.

Unfortunately, while I would agree with you 100%, the "ecologists as god" attitude will only get you trampled by the masses. It does not matter if you are right. What matters is results, and your approach has potential to NOT get results. Work with us and don't get discouraged. How effective do you think you wold be if you just set up a soap box in a park in Brisbane (for example) and started giving your speach to the passerbys? Same problem here. - Marshman

Well, I have tried to correct these errors. I won't bother trying again if I'm going to have carefully crafted words huffily removed with very shoddy Northern Hemisphere/Europe/US centric arguments that introduced species are basically OK!

Unfair and totally inaccurate statement. Australian ecologists are not the only people holding the light - Marshman
Didn't make this comment in the sense that "Australian ecologists are the only people holding the light." That's not what I was trying to say at all. What I was trying to say was that due to a longer history of settlement, larger populations, more scientists etc scientific literature is often dominated with Northern Hemisphere/Europe/US examples. A questionable generalised rule on impacts of introduced species based on the Northern Hemisphere examples, and particularly European and US examples, is utterly inapplicable to a isolated island continent with higly unique and endemic biota like Australia, and frankly, it is utterly ridiculous for Guettara (spelling?) to suggest that it is. Codman 00:03, 17 September 2005 (UTC)Codman
OK. Obviously both points of view no matter where they originate deserve voice. I can tell you my experience in Hawaii is that introduced species here have been far more disasterous than even what you see in Australia, and of course there are reasons why, but it is not the scientists that are saying it is ok in No. Amer. so it must be ok everywhere. As you well know there are factors in operation that must be accounted for having to do with previous periods of isolation, etc. Do not assume those reworking your additions are simply not aware of the problem for the reason it is not such a problem in Europe and No. America. I'd assume that people that do not understand the problem really do not understand, and places like Hawaii and Australia make for excellent examples to bring these people along to a better awareness of the threat. That webpage link you deleted was an amazing argument from complete ignorance by a person with at least an IQ score (he could write?). - Marshman 02:45, 17 September 2005 (UTC)
Australian flora and fauna are just so different. I get a thrill of just how different they are, of how most major functional groups are filled by taxa different from those in the Northern Hemisphere. Australia really is/was an amazing island laboratory of evolution; an example of what happens when dominant Northern Hemisphere groups/taxa are kept out by geographic isolation and different groups/taxa get to have a go instead. But it also makes me desperately sad because many of the unique species and ecosystems that resulted from this marvellous island laboratory of evolution have been stuffed to pieces by introduced/invasive species.

Codman 06:02, 17 September 2005 (UTC)

References??? I'm busy as all hell. Wikipedia is a distraction, not my life. Why should I bust my gut chasing down references and typing them up? I would have put them up eventually, but clearly you would have moved my article whether I'd put references in them or not.


Codman, please climb off your soapbox and take the chip off your shoulder. A number of folks with excellent qualifications have worked on these articles and you can work together with other editors to make the articles better - if you adjust your attitude. You might also keep in mind, in my own case, that I am from the land of the insect from Hell (Solenopsis invicta - otherwise known as the fire ant), of the Asian tiger mosquito, of kudzu, and many others. I'm sure the other editors of these articles can point out similar cases in their backyards. So we do know a bit about the hazards of invasive species.
But it's not all so black and white. I would hate to give up my apples (which compete quite well in the wild in many areas of the US, thank you), and who can I blame for poison ivy, which certainly acts like an invasive, but is native.
There are a number of factors you are ignoring in your crusade. One is that the mix has already occurred and no matter how much you'd like to reverse it, it's not practical nor even possible to do so. Another item you might as well face right now is that human beings are a pretty good example of an invasive species. Are you willing to deal with the rammifications of that?
Not all "invasions" are human related. We've had Carribbean insect species blow into Southeastern USA during hurricanes. Every now and then "Nature" plays such a trick, so I'm not always ready to take a guilt trip for my species. Not all introductions are intentional either. Icerya purchasi, the cottony cushion scale was accidently introduced (despite inspections of plants) to the US from Australia, and proved to be a devastating pest here. But eventually the pest was brought into control by the importation from Australia of its natural enemy, Rodolia cardinalis. Presently the fire ant is being brought under control by the imporation of its natural enemy, a phorid fly.
So there are shades of gray that you don't seem to be recognizing. One last item. Suppose we draw a line and say, OK here is the end. There will be NO MORE importations of ANY non-native species to ANYWHERE. My question is: how are you gonna enforce it? Pollinator 13:39, 15 September 2005 (UTC)
"Not all "invasions" are human related. We've had Carribbean insect species blow into Southeastern USA during hurricanes."
That is a "natural" event, and therefore a non-issue. "Introductions" are fine if they happen naturally. It is frivolous human introductions I am against.
"Suppose we draw a line and say, OK here is the end. There will be NO MORE importations of ANY non-native species to ANYWHERE. My question is: how are you gonna enforce it?"
This one of those "big questions" with no ready answer, just like the issue of the handful of crops/animals humans depend on for sustenance (and which in most parts of the world are introduced species.). So, I don't have a ready answer and I don't know how WE are gonna enforce it (though education and border quarantine spring to mind). NEVERTHELESS, we don't have to have ambivalent articles on Wikipedia which lead people to think that it's basically OK to introduce exotic species. (Which it most certainly is not.) - Codman 07:30, 17 September 2005 (UTC)
I can weigh in here. I'm from Hawaii. In the lowlands of the islands (especially O'ahu) one is hard-pressed to even find a native species. Botanical surveys that I conduct generally reveal about 6-10% natives among plant species, with biomass of natives typically accounting for 2% or often much less. I think Codman is preaching to the choir in terms of the editors working on these article and needs to simply tone down his retoric. He will find a lot of sympathetic people here to champion the ecological POV. - Marshman 19:09, 15 September 2005 (UTC)
Agreed. This article has always struck me as a little ambivelant about the effects of introduced species to native biota. Especially as when I write articles about bird species it seems to crop up most often as a threat to said species. But we still have an obligation to write a neutral accurate and above all else encyclopedic entry on the subject, not an op ed piece. Sabine's Sunbird 20:35, 15 September 2005 (UTC)
I think there is plenty of agreement among most of those contributing in this area that our Australian friend is pretty close to dead on in his concern, and the science I'm aware of supports him. The challange for all of us is to make the presentation reflect this in a quiet, logical way, being mindful that every POV is fallable at some point - Marshman 20:43, 15 September 2005 (UTC)

Question: Where do invasive species come from?[edit]

Where do invasive species come from?

Introduced species (that establish).

Where will invasive species continue to come from?

Introduced species (that establish).

Therefore, to be responsible, places like Wikpedia should NOT have ambivalent articles on introduced species, and should emphasise the inherent risks with human introductions of species, risks so great that the practice should not occur any further. I therefore expect to see my article appear in invasive species courtesy of those who have already moved it, and a less ambivalent introduced species page. cheers.

Unfortunately, the world is full of people with different points of view. Do you seriously think everyone cares about biodiversity? My guess is you are a graduate student with minimal real world experience (sorry, if I'm off base). Look at the popularity of Crichton's "State of Fear", a totally unscientific, misinformed novel about global warming that is very popular. I read a recent review that suggested the real point of the novel (if not Crichton's intent) is that if ecologists are going to save the world, they damn well better come up with a better approach to how they swing public opinion. Take New Orleans: the focus for weeks has been on just who (politically) is to blame. But the truth is barely being discussed: the people of Louisiana (and maybe all of us Americans) are to blame for letting the wetlands of the delta diasappear; wetlands that once protected the city from storm surges (and who knows what role global warming played in the severity of the storm in the first place). - Marshman 19:26, 15 September 2005 (UTC).

Yes, I admit I got a bit aggro with this. I appreciate the more constructive comments. Will now try and amend things in a way people will agree with.


Codman 00:03, 17 September 2005 (UTC)Codman

Am happy now with the section "Control of introduced species."

Thank you

Codman 02:28, 17 September 2005 (UTC)Codman

Perhaps one of the best examples of an introduction with negligible impact is that of the Little Owl to Great Britain. An accident of geology meant that this species didn't get to Britain before it was cut off from the European mainland, so when it was introduced in fitted into the same niche as on the continent some 20 miles away. The real problems seem to arise when species are transported halfway around the world to totally alien environments. jimfbleak 06:13, 17 September 2005 (UTC)
I have reworked Control of introduced species to be about control of introduced species and legal ramifications rather than a rehash of invasive species arguments. Garglebutt / (talk) 05:59, 22 September 2005 (UTC)

Proposed changes to Introduced Species Page[edit]

We propose to make the following changes to the introduced species page. We will add information to the section titled “The nature of introductions.” Specifically, we propose the addition of two main subcategories that describe human involvement in species transport: intentional and unintentional introductions. Under intentional introductions we will add information regarding the common motivations that underlie human mediated introductions. We plan to merge some of the relevant examples that already exist on this page into the new text. Examples that do not fit under “the nature of introductions” will be moved to appropriate sections such as “Common introduced species” or other pages (List of introduced species). The subsection on Reintroduction will be merged into the newly created section about Intentional introductions. Finally, we propose to move the section on Control from the Introduced species page and merge it with new additions to the Invasive species page. We recognize that many introduced species are subjects of management efforts. However, the term “introduced” is a neutral term, and therefore information about control measures is better served on the invasive species page. We support creating a link to this topic in the “see also” section. We expect to post these changes in the next few days.- PBG250 00:03, 6 December 2005 (UTC)

Changes Made[edit]

As discussed above we have added information about the nature of introductions to this page. The section on reintroduction was merged into the new text and the section on control was removed for reasons stated above. There are many examples of introduced species embedded in the text of this page. We feel that separate sections about animals, plants, and diseases are somewhat redundant and could be more simply presented on the list of introduced species. For now we have left these sections as they are and await comments on the changes we have made. -PBG250 22:29, 9 December 2005 (UTC)

Invasive etc[edit]

While this article makes some attempt to explain the controversy over introduced species, I think there is much room for improvement. For example, although it mentions that from some POVs, all introduced species are invasive, it doesn't really mention that whether something is invasive or not is often debated. Here in NZ for example, certain species of palm are being added to the list of weeds by the ARC (a move which is supported by many ecologists (and botanists)) but there are others disagree that these species are invasive or a threat. Also the bit on Pinus radiata might be a bit misleading. While it is a very commercially important crop, as with other introduced species it's generally not considered beneficial when it is found in natives forests, especially forests reserves and indeed would usually be considered a weed. Possums especially and also deer to a lesser extent are of course generally regarded as all around bad. Nil Einne 03:57, 15 August 2006 (UTC)

Introduced species[edit]

A number of animals such as sheep, cattle and horses have been introduced to many countries that they are not native to. Would it be fair to say that these animals are Introduced. --WikiCats 07:26, 29 September 2006 (UTC)

Yes :) Djlayton4 | talk | contribs 12:41, 30 June 2007 (UTC)


An introduced species Blah Blah (also known as naturalized species or exotic species) is an organism that is not indigenous to a given place or area and instead has been accidentally or deliberately transported to this new location by human activity.

If we define introduced species as only those introduced by humans (and not chance events, say), where is the more general article on non-indigenous species? Wouldn't it be better to start with such an article as the main topic, then have specific articles on the more limited subjects of human introduced species and invasive species (which need not be introduced by humans, but do not cover all non-indigenous species either.

I would also like to see a reference given for the definition. Richard001 11:28, 11 May 2007 (UTC)

Self introduced species are considerably less common than human introduced ones. At least insofar as ones we have witnessed and recorded. Conventionally introduced species refers to ones where we did the introducing. Ones that managed it by themselves are referred to as colonising species. Sabine's Sunbird talk 11:35, 11 May 2007 (UTC)
We at least need more mention of this subject - e.g. how species are naturally introduced (storms, seeds sticking to birds feathers or snails clinging to their feet), and the evolutionary theory behind it (species coming from a larger land mass tend to outcompete those on smaller islands where the pace of evolution is slower). It would probably justify a whole article, but I can't identify one at present. Biological dispersal does cover one side of it, but isn't very specific and doesn't go into the consequences of the dispersal. Richard001 11:48, 11 May 2007 (UTC)
I agree completely, but this isn't the article for that. Introduced species has a very clear meaning in ecological literature, it refers to human assisted ones. An article on biological colonisation would be appropriate for what you're suggesting, and could be linked out of here. Sabine's Sunbird talk 03:41, 12 May 2007 (UTC)

Significance of the Photo of Clover[edit]

The photo that appears at the very opening of this article has a poor caption that should be improved. The subject of the photo is the bugs, not the plant. If those insects have some sort of relevance to the topic, then the caption should be changed to explain what species they are and what they are doing. If they don't, the photo should be removed and replaced with another (there are plenty of photos of introduced species around). Djlayton4 | talk | contribs 12:41, 30 June 2007 (UTC)

Admittedly the newer caption has more relevance to the topic, but I feel that the opening photo should simply be of something non-native. A photo should pertain to the text near it and there is nothing in the introduction about an invasive plant increasing biodiversity. If that is mentioned in the text somewhere, then the photo should be moved next to it. For someone just opening the article, however, I feel that the bug photo is unhelpful. And I don't see what political correctness has to do with anything. Thanks. Djlayton4 | talk | contribs 09:20, 10 July 2007 (UTC)

Proper categorization of the article[edit]

The article was previously categorized in Category:Ecological definitions. I removed this cat and added instead Category:Biogeography and Category:Conservation. Reasoning: introduced species are usually mentioned either in the context of species distributions (hence biogeography) or of conservation biology. Sure, not every introduced species is a conservational concern, but we don't use the term "introduced species" when talking about gardening anyway! Ecology is a broad field and I think the categorization in this case should be more specific. Gidip (talk) 23:25, 20 October 2008 (UTC)

Proposed Changes[edit]

I am part of a group of graduate students at UC Santa Cruz has an assignment to improve this page. Given that the Wikipedia Ecology group rates this page as high on the importance scale and a B on the quality scale, I think a major addition to the page is appropriate. Specifically, I think that the page should include:

- More information of the worldwide impacts of introduced species. There have been some previous comments that it treats introduced species as trivial. I would like to bring in quantification and other information on the global impacts.

- Some application of ecological theory. The page is currently rich in antidotes and examples, but I would like to see a discussion of why species are more likely to be introduced given human activity, why they sometimes spread and sometimes don't, how convolution can help shape a species fitness in its native habitat, and how predator release may help make an introduced species invasive, et cetera.

- A discussion of the argument that native and invasive are constructed concepts. This could center on the evidence reviewed in Warren (2007) and the subsequent response by Richardson et al. (2008).

Warren, CR. 2007. Perspectives on the 'alien' versus 'native' species debate: a critique of concepts, language and practice. PROGRESS IN HUMAN GEOGRAPHY 31, no. 4 (August): 427-446.

Richardson, D. M., P. Pysek, D. Simberloff, M. Rejmanek, and A. D. Mader. 2008. Biological invasions-the widening debate: a response to Charles Warren. PROGRESS IN HUMAN GEOGRAPHY 32, no. 2: 295.

--Devonds (talk) 01:18, 27 November 2008 (UTC)


Hello, xenophyte redirects here but this word is not present in the article. Could you delete the redirection otherwise could you explain this word in this article? Pamputt (talk) 12:51, 15 November 2011 (UTC)

Clarification for locally cultivated species[edit]

The terminology section seems to suggest that any domesticated/cultivated species is invasive (most visibly the table of terms). The section 'Nature of introductions' on the other hand seems to suggest that only cultivated species that were introduced by transportation are introduced species. I think the terminology section should include a sentence clarifying whether species that were locally domesticated (e.g. turkeys in North-America, domesticated rabbits in Europe and rice in East Asia) are introduced for the scope of this article. Because the exact definition of introduced species seems unclear and may be controversial I hope several people are willing to grant us their opinion on what the sentence should state. PinkShinyRose (talk) 22:11, 11 July 2012 (UTC)