the naturalist man's picture

Is a re-introduced speices still native?

This forum has come about from a passing comment in a roe deer observation.

Roe deer bones dating from before the last ice age have been found in England, but they were extinct in Wales and probably in England by the early 19th Century due to over hunting. They just clung on in the highlands of Scotland. All the roe deer you see in England and Wales are decendents of animals released in the late 19th Century.

Therefore, if the roe deer we see today are decended from continental individuals can the species truely be considered native. I'm not going to say my thoughts one way or the other yet, however, some other examples:

Red kite, some of the introduced red kites in England and Scotland are from Wales and so could be considered from native stock, but these were suplimented with birds from continental Europe.

Capercaillie, a bird known to have been in Britain since at least the last ice age, 12,000 years. It went extinct in the early 19th Century. There have been three attempts to re-introduce it, two failed and the latest has lasted around 100 years, is it a native species? A similar story for the white-tailed sea eagle.

Conversely, fallow deer introduced around 400 years ago; rabbits 1,000 years ago; brown hares, two thousand years ago; house mouse around 3,000 years ago... when does a species become native?

Finally, the eagle owl. There is evidence that there were eagle owls in Britain at least as far back as around 5,000 years ago. It is said that beacuse we only have such evidence from human habitations then the eagle owl was not wild but the remains were of tame birds brought by human migrants.

I have greatly rounded off dates here as I'm just trying to make some points. If you want to correct my chronology with exact dates or other examples then please feel free to do so.

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the naturalist man's picture

Collared dove

....then there are collared doves. They found thier own way to Britain in the 1950's and are now fully established. Are they now native, or in some way an honorary native species? If their population crashed should we spend time and money creating a Biodiversity Action Plan to save them as a breeding species in this country?

Graham Banwell

Visit the iSpot Yorkshire forum for information on events, issues and news relating to 'God's own country'
http://www.ispot.org.uk/forum/8411

AB25426 - abbey's picture

reintroduced / introduced / influenced

Some of my comments copied from the original observation and some additional ones.......
It's a difficult one to determine an exact defintion for, and probably pretty subjective. If something is native because it occurs naturally without human intervention then does it count if the habitat that instigated it's presence is created due to human intervention? - which most are!

To me, a reintroduced species is native if it was originally removed by human intervention - in such cases humans have only cancelled out their original intervention. So, Roe deer are native in my mind.

I don't think I consider introduced species native, no matter how long ago they were introduced.

Species that have found their way here naturally, I would consider native.

I think human intervention to retain or reintroduce a species is appropriate if human action was the cause of their demise.

However, saying all this, I go back to my earlier point about human influence on habitat. Can we really claim that anything that happens is not in some way linked to some human action? Can the presence or absence of any species be completely without human influence?

Abbey Burn
OU Student BSc Natural Sciences

Gill Sinclair's picture

Native species - a subjective subject :-)

Just to add a comment I have already made in response to some roe deer photos from Abbey:

I don't know what the official or scientific definition of 'native' is, but the common sense viewpoint seems to me to be that roe deer as a species are native to Britain, even though the current populations in England may have been reintroduced using individuals from another part of Britain (ie. Scotland).
When I go wild mammal watching overseas, I think I'm quite picky in that I don't like to count a sighting if the species is completely introduced (ie. it's never existed in that country/area, but has perhaps been introduced for hunting or whatever), but if humans have extirpated a native species and then reintroduced it, I would count it as native regardless of how much time has passed.

And to add further comments after reading the posts in this forum:

I therefore agree that a reintroduced species is native if it was originally extirpated by humans (whether by hunting, habitat destruction, introduction of an alien predator such as rats or cats etc).
I also agree that species that colonised a country naturally should be considered native.

However I do think that, after a certain amount of time, an introduced species may become considered as part of the native fauna, but the amount of time is highly subjective - for me, rabbits, brown hares and house mice now seem to be native, but brown rats, grey squirrels and sika deer are not!

Gill Sinclair
OU Certificate in Contemporary Science
www.gillsinclair.net
Twitter @Gill_Sinclair

miked's picture

I seem to recall there has

I seem to recall there has been extensive discussion on this issue in British Wildlife magazine with various dates of introductions/fossils etc.
Broadening out the discussion, what do you think about 'non-native' plants i.e. over half the flora? I suspect many of the same arguements apply to any kinds of introduced species.
What if, say, the very few native species of trees in uk were all wiped out by disease or climate change and we've not introduced or allowed to be planted non-native species, would it be acceptable to have no forests for our children?

bobthebirder's picture

native/not native

I think that to answer this we need to think about the genetics of these populations. In my view it is quite possible to make valid generalisations about the genetic make-up of a group of organisms without having any actual DNA data.

So in the case of Roe Deer the genes in the original UK population disappeared when the last animals died out in this country. The introduced deer would have contained a different gene set, as they came from a separate breeding population abroad. So the species is native, but the animals we see today are not, and never will be.

If at some point in the future taxonomists decide that the Welsh red kites are sufficiently different to warrant their own sub-species then the introduction programme will have been guilty of making them extinct by cross-breeding with European birds. The RSPB decided to cull the ruddy duck for just such a reason (quite rightly in my view, although much too late).

Bob Ford

Gill Sinclair's picture

native/not native - roe deer

Just in response to one of Bob's comments ("The introduced deer would have contained a different gene set, as they came from a separate breeding population abroad."), I understood from earlier comments that the English roe deer were reintroduced from Scottish populations, so not really "abroad"? It seems entirely feasible that, given time and the right habitat corridors, the Scottish roe deer would have recolonised England naturally. I live in Hull, and the roe deer in our area seem to be quite opportunistic and are gradually expanding their range closer and closer to the city, as well recolonising areas of farmland in East Yorkshire that have been set aside and where there is now less disturbance than there used to be.
(By the way, this discussion does seem to be treating Scotland and England as separate countries, whereas they are surely still both part of Britain :-) )

Gill Sinclair
OU Certificate in Contemporary Science
www.gillsinclair.net
Twitter @Gill_Sinclair

AB25426 - abbey's picture

Reintroduction source...and other questions!

Although England and Scotland are seperate countries, the fact that they are the same landmass is presumably more relevant in discussions on extripation of a species? It does seem likely that roe deer would have recolonised England from Scotland. I understand, although I'm not positive, that roe deer were reintroduced to England from mainland Europe - Germany? If this is correct, then presumably this is because they only survived in the Scottish Highlands so numbers would not be high enough to take from Scottish 'stock'? If roe deer evolved before England was cut-off from mainland Europe then surely they are the same species as they original native species anyway? If not, then can the Scottish population still be considered 'pure native' as they are likely to have bred with those that were reintroduced?

Abbey Burn
OU Student BSc Natural Sciences

the naturalist man's picture

Roe deer

There was a relic population of roe deer in the Scottish Highlands and a few pockets in the Sottish lowlands. I doubt the highland population would have crossed the mountains and spread south but the lowland populations may have. The colonisation of England and Wales was by continental stock, I'm not sure where from. None of the roe deer in Britain, not even the relic population in northern Scotland, are considered genetically diverse enough to be a seperate sub-species. I have no evidence they brought roe deer, but the Romans, Normans and Tudors were big on bringing deer from the continent and may well have brought roe deer. Therefore, the British population, even prior to the near extintion in the 19th century, may well have been of mixed origin.

This was the case with red deer. The native stock was 'replenished' with continental animals by the Normans who protected them in massive deer parks; Royal Forests. Following the first Black Death in the 14th Century there was a breakdown in social structure and the Royal Forests lost their protection. Red deer, as with roe deer came close to extinction in much of England (except south east), Wales and southern Scotland. The Victorians bred continental red deer with other, larger species, e.g.Wapiti (Cervus canadensis) from Eastern Asia (also found in Western USA). These 'improved' animals escaped and bred with native stock. Therefore many of the animals seen in Britain today are not even pure bred red deer species, especially the larger animals you see in deer parks. Are these native? By Bob's correct definition thier genes are 'corrupted' by the genes of another species and therefore should not be considered native. What if all the animals in Britain were found to be hybrid, having the genes of at least one other species, would red deer still be native?

This is thought to be the case with the Scottish population of wild cat (Felis silvestris silvestris). It has been proposed that there are domestic cat (Felis silvestris catus) genes in all of them. Are they still native?

Graham Banwell

Visit the iSpot Yorkshire forum for information on events, issues and news relating to 'God's own country'
http://www.ispot.org.uk/forum/8411

Gill Sinclair's picture

(Re)introduced deer

Ah, I see - I thought that some of our English roe deer were descended from introduced Scottish stock, whereas I see now that they are descended from introduced continental stock.

This is a very interesting discussion, and I must admit that I had only previously considered native/introduced debates at the species level, rather than at the genetic level. I therefore viewed species that had been reintroduced following extirpation as native. However, I am studying the OU's Darwin & Evolution course at the moment, and I would still say that, as long as we're definitely talking about the same species (ie. individuals from separate populations can still breed and produce viable, fertile offspring), a re-introduced SPECIES will always be 'native' even though the INDIVIDUALS in it are not descended from native stock.

However, the issue of populations restocked using animals that are now considered as separate species is different. I assume that when wapitis were used to restock red deer populations, they were still considered to be Cervus elaphus? (I have learned something today as I didn't know that wapitis were classified as Cervus canadensis, but now I've had a look on the internet I see that there was some evidence from mtDNA in 2004 that gave rise to this change.) In that case, the species status of red deer in Britain is indeed in question.

PS. I can now add another mammal to my 'life list', as I have seen 'red deer' in Canada :-)

Gill Sinclair
OU Certificate in Contemporary Science
www.gillsinclair.net
Twitter @Gill_Sinclair

Derelict's picture

Cervus as genus or species?

The genus Cervus is an interesting genus because it is an excellent demonstration of the sheer artificiality of the current definition of "species" which puts far too much weight (in my opinion) on mere isolation, notwithstanding that isolation can be an accelerant to the process of evolutionary divergence.

My view of Cervus is that many of its constituent "species" are no more than what in humans would be called "races". I don't think we'd dare follow the early line of identifying 'Caucasian' as a discrete Homo species or sub-species would we? Yet we continue to do it with Cervus. Unfortunately Cervus is an example of dynamic evolution in progress in a large animal where there are morphological differences which WE can recognise but which when push literally comes to shove clearly aren't that important to the deer!

To really identify/define a true species you have to identify the fundamental characteristics that those animals use to decide who to attempt successful reproduction with. In deer it's chemical. If you smell right that's good enough. The result is that we recognise numerous species of Cervus and more subspecies of Cervus elaphus than you can shake a stick at, whereas the truth of the matter is that when opportunity arises they hybridise and produce fertile offspring which in my view ought to be enough to say they are the same species.

Another thing that concerns me about our current definition of "species" is that it bends over backwards to avoid considering those situations in which humans have played a role - e.g. domestic breeds, genetically-modified organisms. But that's another story!

er2938's picture

Biological definition of a species

I neither agree nor disagree with your comments above, however I think it is important to note that that the ability to interbreed and reproduce successful offspring is just the 'biological definition of a species'.

Where does that leave (the very many) species that use asexual reproduction or a mixture of sexual and asexual reproduction based on environmental conditions and habitat?

Ultimately taxonomy is a system of agreed conventions subject to change, not an exact science. I don't know much about the genus Cervus, but imagine there must be some advantage to the current classification.

There seems little scientific value in studying and classifying domestic breeds and genetically modified organisms to me. They are ultimately 'designed' for commercial purposes.

Erwyn

Derelict's picture

Biological definition of a species - response


I don't know much about the genus Cervus , but imagine there must be some advantage to the current classification.

There's plenty of literature out there and this may be your chance to find out! It is still too firmly rooted in 19th century morphological studies and numerical taxonomy. We wouldn't do the same for Homo which has much in common with Cervus in terms of recent geological timescales vis-a-vis distribution and variation.


I neither agree nor disagree with your comments above, however I think it is important to note that that the ability to interbreed and reproduce successful offspring is just the 'biological definition of a species'.

I don't understand the relevance of this unless you want to expand a discussion on native/non native mammals into mycology. That said the biological definition of species is the one that the other multicellular biota seem to prefer to work to.


Where does that leave (the very many) species that use asexual reproduction or a mixture of sexual and asexual reproduction based on environmental conditions and habitat?

Aha! I must be repling to a mycologist. That's one for your mycology textbooks. In other multi-cellular organisms most of these ancillary mechanisms are fortuitous workarounds when population densities of compatible individuals are too low. Remember this is a thread about native/non-native species.


Ultimately taxonomy is a system of agreed conventions subject to change, not an exact science.

see my posting on hybrids further down...


There seems little scientific value in studying and classifying domestic breeds and genetically modified organisms to me. They are ultimately 'designed' for commercial purposes.

It's an interesting standpoint, ignoring an increasing portion of the larger mammals because they're er... inconvenient. It would upset archaeologists. Scientists are unduly chary of dealing with domesticated species because they don't follow a definition of 'evolution by natural selection' and we seem to have a thing against humans as agents of evolutionary change (except for extinctions!) Yet these animals have been subject to selection by environmental factors like all other life-forms on the planet. The process is the same, it's just that when classical evolutionary process was being elucidated breeds were problematic. Now we've done much of the work we can afford to be a little more inclusive. Holistic models are generally better than those with exclusions.

Generally I found your comments diverting but rather off the topic of the thread. Not knowing something which you can find out easily enough isn't really an excuse to talk about something else. There must be a fungi forum.

er2938's picture

Biological definition of a species - response

Generally I found your comment uninformed and assuming. And you know what they say when you assume... you make an ass (hybrid!) out of you and me.

Sexual reproduction is common in fungi, so how you have come to assume I am a mycologist I have no idea.

In the previous post you have made the point that deer species should be re-classified because they can interbreed to produce viable offspring. To this point I annotated that this is a very stringent classification of a species known as the 'biological classification of a species' and not that helpful to taxonomy. Taxonomy is an agreed framework based on a wide number of different factors including the ability to reproduce, but also ecology and behaviour.

Please also bear in mind that mammals, other animals and plants evolved from species without sexual reproduction, including millions of microbes. Your narrow classification of a species has just excluded all your ancestors.

Ignoring other factors and lumping every deer species together because they can interbreed isn't helpful. There must be a continued advantage to their current classification. Naturalist Man's comments regarding gibbon species' below also highlight the need to split species even though they can interbreed. Maybe you could share your 'knowledge' of Cervus like a good scientist, rather than telling people with less knowledge of the particular subject off.

Wrapping up Homo in just one species has more to do with politics than taxonomy.

It's good to have a debate about these things within a wider context, that is what this website is about. You may disagree with what I have to say or don't find it relevant, I do... I do find them relevant to the native/non-native discussion, given the increasing divergence in DNA between species in different locations.

You have misinterpreted my point regarding domestic species. My point is, why bother spending millions and millions of pounds classifying and researching domestic species purely designed for commercial purposes? The pursuit of scientific enquiry isn't free and the money could be much better spent elsewhere.

the naturalist man's picture

I feel the comments you both

I feel the comments you both have made in the above discussion are very interesting. I created this forum in mammals purely because the issue that triggered it was related to mammals. However, I never intended it to be purely mammals.

I am glad it has run so long and gone off at various tangents. The tangent concerning "What is a species?" I think deserves its own forum, therefore I've created one. This time I've put it into "Other oganisms" so everyone, regardless of specific interests can feel free to participate.

I feel it would be useful if you both (derelict and er2938) could duplicate your comments above in the new forum, starting with "Cervus as genus or species?". As I have not participated I did not want to presume by moving your discussion myself as I have with some others.

The new forum is at:

http://www.ispot.org.uk/node/19116

Graham Banwell

Visit the iSpot Yorkshire forum for information on events, issues and news relating to 'God's own country'
http://www.ispot.org.uk/forum/8411

er2938's picture

Thanks

Thanks. Glad you don't mind about tangents!

er2938's picture

typos - oops

Two corrections, message should read 'Generally I found your comment informed but assuming'!

gibbon species = baboon species.

Gill Sinclair's picture

Wild cats

May be getting off-topic for this particular discussion(?), but following on from Graham's comment above, can I just clarify that the domestic cat in Britain is descended from the wild cat (Felis silvestris) and is a sub-species of it, and can therefore interbreed with it?

I saw this article on the BBC http://news.bbc.co.uk/1/hi/sci/tech/6251434.stm which suggests that domestic cats are not descended from Felis silvestris but from some (unhelpfully unspecified) felid from the Middle East - what species would this be?

I would have thought that the interbreeding of wild and domestic cats in Scotland is evidence that British domestic cats are indeed descended from Felis silvestris, assuming that the offspring are viable and fertile (and I guess they must be if there is great concern about the purity of wild cats being compromised more and more as time goes on).

I would have thought the interbreeding would gradually affect the physical appearance of the wild cat until all individuals eventually looked just like domestic moggies, rather than meaning the wild cat wasn't native anymore? A case of rather rapid evolution in action, but with sad consequences if we lost the distinctive look of Britain's only remaining wild felid, which we could only restore with the introduction of continental stock!

Gill Sinclair
OU Certificate in Contemporary Science
www.gillsinclair.net
Twitter @Gill_Sinclair

AB25426 - abbey's picture

Wild cats / Domestic cats - biological classification

Again, this is a little off-topic but Gill's post has led me to question my understanding of biological classification. I understood that a key point in the definition of 'species' is 'capable of interbreeding'. I also understood that the naming convention for species is 'Genus species' and for subspecies is 'Genus species subspecies'. This suggests that Felis silvestris and F.catus and seperate species, yet they are capable of interbreeding? Why were they reclassified as seperate species (in the 1960s?) when they fulfil the definition of 'species'? Or is there another key to the definition of 'species' that I'm missing? Additionally, the article which Gill refers to suggests that they're not even the same Genus, or family for that matter?!

Abbey Burn
OU Student BSc Natural Sciences

miked's picture

There are many different

There are many different definitions of 'species', 'capable of interbreeding' is a rough approximation that works sometimes.

the naturalist man's picture

Wild/domestic cat

The British wild cat is considered by some to be a seperate sub-species, Felis silvestris grampia. Domestic cats are currently considered to be Felis silvestris catus not a seperate species Felis catus. The problem is domestic cats are considered to have evolved from Felis silvestris lybica yet another sub-species and distinctive from the European sub-species Felis silvestris silvestris.

In this case the arguement for British wild cats being a seperate sub-species, or even seperate species is based on it being unable to breed with other wild cats due to physical isolation - the English Channel. Unfortunately for them we brought F.S.catus with us 5,000 years ago. For example, European white-headed duck and American ruddy duck are considered seperate species, yet they breed to produce viable hybrids. The reason they are seperate species is the physical barrier to breeding of the Atlantic Ocean - then we came along!

This raises another question - I'm full of them! Should we re-assess the species status wen we break down the physical barrier? Also should the hybrid animals be considered a seperate species?

Graham Banwell

Visit the iSpot Yorkshire forum for information on events, issues and news relating to 'God's own country'
http://www.ispot.org.uk/forum/8411

AB25426 - abbey's picture

Re-assessing species status

Sounds like I had duff info on the cat reclassification - never trust Mr Google!
In the absence of an absolute rigid definition of 'species', it seems like the decision on when to re-assess a species status will always be subjective. Assuming we do apply the definition rigidly, and species such as the European white-headed duck and American ruddy duck were classified when their breeding behavious was unknown (due to physical barrier), now that it is known and proven that they can produce fertile offspring, it would seem reasonable to re-assess. This is taking literally the 'can' (technically possible) as aposed to 'haven't' (due to physical barrier). How do we determine when a fertile hybrid becomes a subspecies?

Abbey Burn
OU Student BSc Natural Sciences

the naturalist man's picture

When is a hybrid a species

Good question, I guess it would be when the hybrid's genetics and appearance 'stablise' for many generations. I'm not sure if there is a definate answer, anyone else know?

Graham Banwell

Visit the iSpot Yorkshire forum for information on events, issues and news relating to 'God's own country'
http://www.ispot.org.uk/forum/8411

Derelict's picture

When is a hybrid a species?

There is no answer. "Species" is a construct that we use for convenience to differentiate life-forms. Unfortunately nobody told the biota so the biota don't know the rules. A viable hybrid is evidence that two of our definitions of "species" (i.e. those for the parents) may be inaccurate. If the hybrid can produce viable offspring then that proves it.

There's a classic case of this from the Drosophila world where two american species with overlapping ranges became one when it was realised that all the id'd specimens of one were male and all the id'd specimens of the other were er female.

Gill Sinclair's picture

Re-assessing species status

I agree that species' status should be re-assessed when physical barriers are removed - Abbey is right - before that point, the only thing that stopped interbreeding MAY have been the fact that individuals from two populations couldn't physically get together, and that needs to be 'tested'.

I think hybrid animals should be considered a separate species if the hybrids can breed with one another and produce viable and fertile offspring, and individuals can continue to breed with one another for several(?) generations - effectively a new species has evolved in that case. The genetics could be tested to see if they have 'stabilised', but I don't think waiting for appearance to stabilise would be a good measure - look at how much appearance can differ in humans, dogs (artificially-induced variation I know), American black bears with their different colour morphs and markings etc.

Gill Sinclair
OU Certificate in Contemporary Science
www.gillsinclair.net
Twitter @Gill_Sinclair

AB25426 - abbey's picture

Re-assessing species status

I agree that appearance is an ineffective indicator to use, there can be so much variation within a single species.
And I suppose the additional difficulty (when what are accepted as two seperate species breed e.g. in the duck example) would be if the original two 'species' then bred with the 'hybrids', therefore making a multitude of variations in split between the originals. Also, at some point, the orginal 2 'pure species' may cease to exist. Again I think this supports the case for re-assessing them into the same species, with different subspecies. Of course this could in theory result in countless subspecies. How do you then determine what is a valid subspecies if you have 'hybrid' variations of 99/1, 1/99 and everything inbetween.

Abbey Burn
OU Student BSc Natural Sciences

the naturalist man's picture

Another thorny issue

Another thorny issue linked to the question of what makes a native species.

Ring-necked parakeet are causing a great deal of concern with some conservationists. Natural England recently removed protected status from these birds, allowing landowners to take measures to control numbers where they can be proven to be a threat to crops etc. Refer:

http://www.guardian.co.uk/environment/2009/oct/12/ring-necked-parakeet-cull

I find the attitude of some avian conservationist organisations very puzzling. For example, the RSPB seem to be sitting on the fence over these birds, with their feet dangling on the bird's side.

http://www.rspb.org.uk/wildlife/birdguide/name/r/ringneckedparakeet/prob...

Yet they are very much against eagle owls:

http://www.rspb.org.uk/ourwork/policy/species/nonnative/eagleowls.asp

I understand the issues are complex, yet both species are introduced (though there is evidence eagle owls were native until around 9,000 years ago and have been around in small numbers as escaped captive bred birds ever since). Also there is good evidence both cause local conservation concern. So why the inconsistency in attitude?

Graham Banwell

Visit the iSpot Yorkshire forum for information on events, issues and news relating to 'God's own country'
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dw5448's picture

A legalistic view

"Native" clearly begs the question of when who made the first observation or identified the oldest credible evidence.

Wildlife preservation (farming?) is obviously a political arena, with individuals struggling with each other for access to resources, so legal definitions of "native" will be far more relevent than scientific ones.

A few motivated individuals have engineered release of red kites in the Kingdom of Mourne (Northern Ireland), largely against a background of apathy and without any real debate about the value of this, and yet there will be substantial efforts made to protect them. A few red deer have escaped from a deer farm, and have settled in well, but there aren't enough of them for anyone to express concern one way or the other, but if they don't become a pest I can see someone eventually wanting to preserve them. On the other hand, nearby Dundrum Bay is an important site for lactating harbour porpoise, but would be unlikely to figure as a potential marine reserve on that basis alone as HP is a species of "least concern" in red lists. Definitions are clearly important, but those linked to protection seem more important to me.

The genetic approach has added even more confusion in this respect. Our diminished Salmon stocks are being supported to some extent, but I was recently at a seminar that identified several genetic clusters in the Foyle river system (Londonderry), which lead to interminable debate about whether each tributary should be treated as unique and separately defended. The genetic work was originally done to identify which stocks were being caught at sea, which has a much greater impact on the populations at present.

In the end, to me conservation seems to be about popularity with humans, who will then look for justifications for looking after what they like.

Dave

the naturalist man's picture

Anthropomorphism and nature conservation

Thanks Dave, you have opened up a can of worms and tackled a subject I find most conservationists I talk to are reluctant to face, why do we conserve some species and not others? I think this is a whole new question and deserving of a forum to itself. I'll look to start one tomorrow.

A small point, we conserve, especially in Britain, not preserve; preservation is what you do to jam! The difference is preservation is passive, you just leave it to do its own thing; conservation is active, we do something to interfere. May be thats the problem?

Graham Banwell

Visit the iSpot Yorkshire forum for information on events, issues and news relating to 'God's own country'
http://www.ispot.org.uk/forum/8411

er2938's picture

Going native

It is an interesting debate and can get very complicated... as the comments on here show.

I take a more cosmopolitan approach, really. The word 'native' is a human invention, animals/plants etc do not perceive borders in the same way we do. If you go back long enough we'd discover hardly any 'native' species evolved here, but were all introduced or made their way over here at some point. Britain is made up of at least 3 different continents, broken off from the one super-continent Pangaea. Once upon a time you could walk from 'France' to 'Britain'. The English Channel would have prevented rabbits to become a native species, whereas many birds have been able to take to the air and have become native over the years.

In my opinion, a species is native as soon as it settles somewhere (by whatever method) and establishes itself and breeds a succesfull colony of a certain size (subjective I know!). Ring-necked parakeets, Little egrets, Red crested pochards, rabbits, roe deer are all native to me. They belong here.

From a conservation point of view there are always going to be more popular species in our eyes, especially if some introduced species are detrimental to other species. Biodiversity should always be our aim in conservation.

By no means as scientific as any of your arguments, but just my thoughts!

Erwyn

miked's picture

I think this contribution

I think this contribution provides a very interesting perspective on the debate especially the comment "Biodiversity should always be our aim in conservation.".
Britain has very low biodiversity comparing its latitude with other regions of similar latitude and very few endemic species. If you wanted to get rid of all 'non-natives' you may want to go on to remove over half of the existing flora and fauna so ending up with an even more impoverished land.

the naturalist man's picture

Introductions

Just to put a timeline to Erwyn's interesting comments. Almost of all Britain was covered in ice until around 15,000-12,000 years ago when it started retreating, therefore, unlike other areas of the globe, most species have only coloninsed Britain in the last 10,000 years or so. The land bridge between the British Isles and mainland Europe was broken around 8,000 years ago, isolating these islands of ours. Unless you live in Ireland which split away 9,000 years ago before some of the mainland Britain species had got that far. This, in part explains the lower biodiversity found there.

Mike's comments opens another question, do we have the right to introduce new species to increase our biodiversity?

Graham Banwell

Visit the iSpot Yorkshire forum for information on events, issues and news relating to 'God's own country'
http://www.ispot.org.uk/forum/8411

Derelict's picture

Is a reintroduced species still native?

This topic has a rather surprising European dimension - there is an EC-led initiative to make governments consider re--introducing any species that have been extirpated in their countries in the past 8000 years i.e. after the last glacial retreat. This presents some quite interesting challenges because in theory wolves and bears could be reintroduced as being formerly native.Spain may be looking at lions. Indeed if someone dated one of our sites wrongly we could be looking at reintroducing hippos and elephants. The important word is 'consider': it isn't compulsory.

As to fallow deer the position is interesting. These were around in Britain before the last glaciation but didn't make it back until the Romans brought some to Fishbourne in the early part of the first millenium though these appear not to have lasted too long. Archaeologists looking at palaeolithic sites find their bones everywhere (though because we are not sure they are exactly the same species i.e. Dama dama they tend to be called 'Pseudodama'.) Thus they would fail the European test even though they were here before. The fact that they are still here, despite not being in receipt of any European grants, is largely down to the control of firearms.

Gill Sinclair's picture

Re-introducing extirpated species

Do you have any web links about the EU-led initiative please? Sounds interesting.

Gill Sinclair
OU Certificate in Contemporary Science
www.gillsinclair.net
Twitter @Gill_Sinclair

Derelict's picture

Reintroducing Species Natura 2000

It all depends what you want to know! If you look up "Natura 2000" you will get plenty of search results to pick from. Some things (e.g. beavers) are easy. Others e.g. ancestors of domestic animals such as horses are fraught with peril because no-one can decide which of the surviving wild horses is most closely related to what would have been the original wild stock. By some definitions wild and domestic reindeer are different species - discrete gene pools, DNA studies indicating that domestication happened only once. So if you were to reintroduce reindeer which group should you select from?

the naturalist man's picture

Baboons

Another example of how complex, and difficult taxonomy can be was brought to mind by a recent posting on iSpot of an olive baboon (Papio anubis). The Olive baboon, considered a species since around 15 years ago, was once considered a sub-species of the Guinea baboon (Papio hamadryas), indeed some taxonomists consider all baboons to be nothing more than sub-species of the Guinea baboon; a species which it still readily hybridises with where there ranges overlap.

Olive baboons hybridise with other baboon species elsewhere in Africa to the extent that it can be impossible to be sure which species some animals belong to. To complicate matters some of these hybrids are now considered sub-species of the olive baboon - the International Union for the Conservation of nature (IUCN), the body who produce the red data lists for animals and plants, recognise seven sub-species.

Therefore, considering that all baboons can interbreed to produce viable offspring should we consider them as seperate species even though their DNA is different enough for most scientists to consider them to be so?

For more information visit the IUCN web site:

http://www.iucnredlist.org/apps/redlist/details/40647/0

Also there is a good paper on the subject which has free access:

http://www.biomedcentral.com/1471-2148/9/83

Be warned the paper has many technical genetic terms. To sumerise, they beleive there have been multiple isolation and re-mixing of species over the last four million years resulting in a very complex situation.

The most interesting aspect of this paper to the discussion here is that they consider there to be 11 species of baboon not the traditional five. Even more interesting these 11 species bear no relation to the five. The authors say in some cases species which look very different and have different social behaviours are, according to the DNA results, the same species, yet others which look identical and behave identically should be different species.

The million dollar question, therefore, is who is right? Do we seperate species according to differences in their DNA or by the way they look and behave?

Of course the trillion dollar question is, should we care?

Graham Banwell

Visit the iSpot Yorkshire forum for information on events, issues and news relating to 'God's own country'
http://www.ispot.org.uk/forum/8411

RoyW's picture

House Mice & Rats - are they really introduced?

I know that this is a very old discussion, but I've only just found it!
The various points raised have made interesting reading (if a little confusing at times because the thread kept going off at tangents - apologies if this becomes another tangent!).

My take on the original question(s) is that if a species was once native then it remains native - but reintroduced populations from non-native stock are not (if that makes any sense - ie. even an extinct species remains native, but 'stock' deliberately brought in from elsewhere by man is not). Introduced species never become native - 'naturalised' is a better term that is commonly used instead to refer to introduced populations that have long established populations.

Now the question in the title of my post...
Species that have reached the country, and established populations, without human intervention are generally considered to be native (eg. Collared Dove, which spread across Europe during the first half of the 20th century). Similarly, I would expect the same 'native' title to be applied to any organisms that came with these species - for instance, fleas or lice that live on Collared Doves or plants spread by the droppings of migrant birds.
So what about species that have hitched a lift with humans? Many of the species that have accidentally been introduced around the world have never been deliberately transported by man - so why are these species always classed as non native introductions, when species that are unwittingly transported with other organisms are not?
I can completely understand the introduced label given to organisms that humans have deliberately transported, but why do we completely disassociate ourselves from nature when it comes to species that have used us to help them spread around the world?
I thought that it would be interesting to see peoples views about this - I'm not expecting any sort of agreement to be reached!

Gill Sinclair's picture

Accidental introductions

No, I'm sure there won't be any agreement, but it's OK (and interesting) to have discussions without reaching agreement:-)

It's really just a matter of opinion I think, but my own view is that species that expand their range by flying, swimming/drifting on the currents or crossing a natural land bridge are native, but those that only got there because of some anthropogenic mechanism (hitching a ride on a plane/boat/train, using a Man-made bridge/tunnel etc.) are introduced.

Gill Sinclair
OU Certificate in Contemporary Science
www.gillsinclair.net
Twitter @Gill_Sinclair

the naturalist man's picture

Introduced

The forum was set up to discuss issues around the concept of native, non-native 'tags'. I'm glad it has gone off at tangents as it illustrates the artificiality of such classifications.

I feel the problems highlighted in this discussion arise from our desire to artificially catigorise species. Does it really matter if a species is native or non-native when introduced/re-introduced? Surely it is its effect on existing species that matters more than if it were once native or not?

For example the inconsistent approach of certain conservation bodies to eagle owls and sea eagles. The recent video of an eagle owl raiding a hen harrier nest has added fuel to the call for them to be eradicated from Britain; the argument is they are a threat to rare species and there are no records of them living in the wild for at least 3,000 years. This not strictly true, there is plenty of anecdotal evidence but all these are considered to be escaped falconer's birds. Yet the same people are supporting the re-introduction of sea eagles to eastern England even though there is great concern that they could be as destructive as eagle owls in northern England. The landscape, and the ecology of the area has changed significantly since sea eagles became extinct and I would question the viability of such a project. It would appear Natural England are also concerned as they have recently pulled out of the project.

The 'official' classification of eagle owls is non-native and that the birds in Britain today are escapes from falconers. However, there is strong evidence that at least some of them could have found their way on their own from an expanding population in Holland and Belgium.

In short, humans decide what is native and non-native based on what would appear to be movable criteria.

I'd be interested to hear what other people think about this.

Graham Banwell

Visit the iSpot Yorkshire forum for information on events, issues and news relating to 'God's own country'
http://www.ispot.org.uk/forum/8411

Gill Sinclair's picture

Native/Non-native - movable criteria

I think we're getting to the nub of this now:-) As Dave commented above, a good part of conservation is about which species are "popular with humans, who will then look for justification for looking after what they like"!

We don't spend too much time debating when/how brown hares got here because most people (including me) 'like' brown hares (although they can make a nuisance of themselves hybridising with mountain hares).

But the eagle owl debate rages because they are seen as a threat to another, well-liked species of bird (I've also heard that they carry off cats and small dogs, even babies, in other countries - is that true or just alarmist talk?!). If eagle owls had been quietly getting on with life for several decades, my guess is that we would have accepted that some of them at least got here from continental Europe/Scandinavia on their own.

The bottom line is, as humans we have the power to make our own rules about other species and change them when it suits - and we do!

Gill Sinclair
OU Certificate in Contemporary Science
www.gillsinclair.net
Twitter @Gill_Sinclair

Gill Sinclair's picture

Invasive species

Participants in this forum might be interested in the PTES publication "The state of Britain's mammals: a focus on invasive species".
http://www.ptes.org/files/908_sobm_2010.pdf
It's longish (32pp) but I've been working through it and it's a very interesting discussion, not spoiled by strong views either way on the control of non-natives.

Gill Sinclair
OU Certificate in Contemporary Science
www.gillsinclair.net
Twitter @Gill_Sinclair

dw5448's picture

Oh no - the Invasive Species dogfight!

I suppose it had to come up: if you want heat and confusion, some of the suggestions in relation to insects and plants are a great way to raise blood pressure (just as well this is mammals then).

I think the destructive element implied in invasive is important though, and is more of a concern to me than just what animals we happen to be able to see when we are out.

A colleague of mine did a lot of work on rabbit populations which was very well funded pre-myxomatosis (by agriculturalists). No-one cares now that there is no longer such an economic cost, and they are just fluffy bunnies. Whatever happened to mink, coypu, and other things that were going to destroy civilisation?

Must read that report - thanks Gill.

the naturalist man's picture

Cats and dogs, not babies!

There are records of eagle owls taking small dogs and cats, but the tales of them taking babies are false.

Graham Banwell

Visit the iSpot Yorkshire forum for information on events, issues and news relating to 'God's own country'
http://www.ispot.org.uk/forum/8411

alcon_blue's picture

When does a species go from being invasive to being native

Is there a certain amount of time a species has to be here to be native, a rubicon after which a species becomes native. Every species must have arrived here for the first time some time.

One example is the honey bee, which has been here for ages, but is still considered an alien. Homo sapiens arrived in Europe less than 40000 years ago, are we an invasive species (making zebra mussels look soft in comparison)?

Perhaps a species becomes native when it has found a balance within the new ecosystem (supporting the idea that Homo sapiens is still an invasive species perhaps?).

Gill Sinclair's picture

Invasive Homo sapiens

I agree that H. sapiens should be classified as invasive, and not only because of your definition:-)

Gill Sinclair
OU Certificate in Contemporary Science
www.gillsinclair.net
Twitter @Gill_Sinclair

the naturalist man's picture

Human invaders

Good point, humans permanently settled in Britain around 5-6,000 years ago, long after most 'native' plants and animals.

Graham Banwell

Visit the iSpot Yorkshire forum for information on events, issues and news relating to 'God's own country'
http://www.ispot.org.uk/forum/8411

gramandy's picture

to simplify...

....can we just not consider

any species that is here and breeding (I guess in the wild) and spreading has now become native.

RoyW's picture

Simplest isn't always best

This would be an over-simplification, which in some cases would have negative implications for conservation. Sometimes it is very important to distinguish between native species (which got here on their own) and introduced species (which are only here because of man).