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arrazello
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Posted: 18 Feb 2008 Topic: Wall Lizard - Alien Status



Hello Forum.
I am a third year student of Environmental Science. Currrently I am writing an assignment on alien species and have chosen to argue the case that the alien vs. native species debate is outdated and not always appropriate esp. in light of changing global climate.
I want to draw a comparison between the little ringed plover which has native status (despite the first breeding pair in 1938) and the wall lizard afforded protection in Europe but not in England due to its alien status.
If the wall lizard is not a threat to a native ecosystem, it seems somewhat counterproductive in terms of preserving global biodiversity to not afford it protection in the UK. Can the forum offer an opinion on this?

I am also wondering if the wall lizard can be stated as inhabiting mostly artificially created environments?



arrazello
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Posted: 27 Feb 2008 Topic: Wall Lizard - Alien Status



[QUOTE=Suzi]

I don't quite understand how you can say the alien/native debate is outdated unless you are going to be very selective about what you favour. I'm thinking rabbit, grey squirrel and Canada geese as fairly unwelcome. It would be interesting to hear more of your ideas.

[/QUOTE]

Thanks for all the input.

To answer this question, I would need to post the entire essay so maybe after Friday when it is finished, if you are interested, I could do that. Be interesting to say what the forum think.

My essay starts by discussing

1. The arbitrary nature of the alien vs. native distinction:a) Temporally. b) Spatially. c) Inviability of the idea of a truly native habitat. d) Incomplete natural history records.

It was in this first section that I wanted to bring in the wall lizard and little ringed plover. The little ringed plover did colonise naturally but its colonisation relies on an artificially created habitat. Arguably, this is indirect introduction - facilitated by human activity and not in accordance with the IUCN definition of native.

IUCN defines native species as those occurring within their natural range (past or present) and dispersal potential (within the range it occupies naturally or could occupy without direct or indirect introduction or care by humans)

In contrast, Podarcis muralis, has been assigned alien status and is thus denied statutory protection in Britain. I could find no research stating that it significantly and negatively affected ecosystems.

Both colonisations are a result of habitat alteration. One change is embraced and the other rejected. Such legislation seems counter-active when the overall aim is to maintain global biodiversity. Thus, in 'areas where native ecosystems are not being compromised, unashamed protection, where appropriate, of introduced species may be beneficial to global biodiversity'. 

This, of course falls down if there is no protection of that species (Bern Convention) and I had better find a better contrast.




arrazello
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Posted: 27 Feb 2008 Topic: Wall Lizard - Alien Status



[QUOTE=Vicar]Hi Arrazello, & welcome.

"If the wall lizard is not a threat to a native ecosystem"

This has not been proved definitively either way, but anecdotal evidence, and recent research suggests a negative impact upon both Sand lizard and Common lizard status.

In the UK it is true that the Wall lizard is most often associated with man-made structures (including quarries) and cliff-faces; although there are exceptions.

Please keep us posted with your assignment !

cheers,

Steve
[/QUOTE]

Hi Steve and thanks for your interest and welcome. You mention recent research - have you a reference for the journal?




arrazello
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Posted: 27 Feb 2008 Topic: Wall Lizard - Alien Status



[QUOTE=herpetologic2] As with all these bird migrations there may have been a human element to them establishing themselves in the UK - other examples include the collared dove - was that introduced or did it make it to the UK by its own? I have also come across other species on my travels which are said to have come to the UK through their own steam - Eagle Owls and Cranes - a question often remains were they in fact introductions? and does that really matter? [/QUOTE]

Certainly, the establishment of the little ringed plover seems to have been significantly aided by artificial environments.

I agree with you when you say - does that really matter? I don't believe it does. Despite the massive ongoing harm caused by alien species: they should not be thought of as damaging species per se.  Precise delineation of a natural range is unrealistic when we consider that environmental factors are in flux and climate change will redefine the range of many species. What will we do - send them back? Or accept that things change?




arrazello
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Posted: 27 Feb 2008 Topic: Wall Lizard - Alien Status



[QUOTE=herpetologic2]anyway the wall lizards in my opinion do not pose a 'significant' threat to our native lizards compared to the other main reasons why our native lizards are declining - which of course is habitat loss due to human activity -

Why spend money controlling a non native when the money can be better spent elsewhere which would actually do some good - habitat recreation on a large landscale scale perhaps would be a more beneficial venture for nature conservation.....
[/QUOTE]

Interesting to see you write this since (beyond the arbitrary nature of an alien/native distinction) another of my essay arguments relies on how the majority of research has neglected to investigate the interconnectivity of native habitat loss and alien species abundance. Much research seems to treat these as independent factors. Simple correlations between native decline and alien dominance is not proof of causation. Degraded environments are so much more susceptible. 




arrazello
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Posted: 27 Feb 2008 Topic: Wall Lizard - Alien Status



[QUOTE=herpetologic2]
It is simple to lay the blame at the Wall lizards door when it could be a host of other factors which are affecting the native populations - genetics, management, micro climate etc
[/QUOTE]

Again, I think this is another important point. Little attention has been paid to the consequences of changing abiotic factors on invasive alien dominance. I recently read a research paper that reported on alien invasive plants (I think it was cheatgrass and japanese honeysuckle) responding positively to elevated carbon dioxide levels.




arrazello
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Posted: 27 Feb 2008 Topic: Wall Lizard - Alien Status



[QUOTE=David Bird]I should think that most people who have travelled around Europe would agree that the Wall Lizard is one of the lizards that does not need European protection status as it is so widespread and so numerous in most of its range. I believe it was put on because it was rare in the north west of its range, edge of range so expected, and at the time the people who were responsible for putting species forward were based in the north west of Europe and trying to get them protected when their own governments were not listening.
Some species Podarcis siculus were also added as they had subspecies which lived on very small islands with very little area and were an isolated population whereas the widespread Podarcis siculus campestriswas and still is extending its range and is threatening endemic species and subspecies of Podarcis siculus where it has been released or accidentally introduced.[/QUOTE]

Thanks for all this useful information and THANKS to all the forum for the input. It is appreciated.




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