non native europeans

[phil]

hi all. just a few things to put by you all. can someone tell me the difference between british natrix, triturus, lacerta, rana, coronella, bufoand vipera etc. well i'll tell you. nothing at all. so how can people say that carnifex in southern britain are infiltrating cristatus and threatening to polute the gene pool when this does not happen in mainland europe. or that feral populations of messotriton will eat their way through all our native tadpoles when they live in harmony in europe. how do you define native? most of the northern and central european species were once native to britain. its just that some didn't make it back in time before the channel flooded. the fact is that non of our herps are endemic to britain. if the land bridge by some miracle suddenly reformed would we have gangs of looney scientists patrolling our border kicking out any herps that came across. if (when) the climate has warmed sufficiently and elaphe scalaris and longissima, timon lepida , pleurodeles, and countless lacertids begin to stretch their distribution northwards do you think this will negatively affect other herps. i don't think so.how would we stop non native birds from nesting or non native sea fish inhabiting our shores. european non native herps would be unlikely to negatively affect our own, for the simple reason that this does not occur in europe, they have co-existed in similar conditions for millenia. this is of course only my opinion. i think political reasons for keeping us apart from europe, should not apply to flora and fauna. just a few metres below the sea we are part of europe. my views do however only apply to european species. and would under no circumstances include species which have evolved(no matter how simillarly) in other parts of the world.

[willj]

a british native is definied as a species that has successsfully colonised land without human interference. just because we lost a large amount of species during the iceage, that didn't make it back doesn't mean that they are still classed as native.
just from the newt side of things, as far as i'm aware there is no evidence that mesotriton alpestris harm native amphibians, certainly they haven't in the Shropshire population. As for Triturus carnifex. the anwer is that all Triturus species hybridise where they meet. take Triturus blasii for instance. the reason that people are iffy about the species in England is that they are not native to the country, and so they are harming the populations.
as for climate change and species moving their distribution, we cannopt influence what happens there and we shouldn't try too.
as for other species like fish or birds. species are coming and going all the time. the fact is that if it lives in a similar part of the world to Britian, but hasn't colonised it means that something is lacking. and since sea fish can swim across seas, and birds can fly. that means we get thousands of vagrant species every year, which either die or return to where they came. to illustrate it today, january the 13th 2006, there have been a total of 56 non native birds In our country, and i can tell you that i'm 99% sure that none of them will sucessfully colonise this country.

[phil]

this is precisely what i am saying. if any particular creature is innept to deal with our climate or conditions in general it will not successfully colonise. as for people being iffy about new colonists natural or not, perhaps people should think about the non native felines that they put out every night that do irreparable damage to our meagre reptile population every year. so how exactly would you classify a british native? one which colonised when? a.d. or since the 15th century or since recent records began. elaphe longissima has scattered populations in central and northern europe, far beyond its mediterranean homeland. and even though introduced by the romans its classed as native to germany, oh and by the way appears to live without most germans even knowing of its existence, never mind upsetting the ecology.as for newts i thought blasii was a naturally occuring intergrade between cristatus and marmoratus, how can acrested newt(carnifex) harm a population ofcrested newts(cristatus) when both naturally intergrade to a limited extent in europe and yet both subspecies still appear to breed true to form. why would this be different in britain. in human terms the last ice age ended a long time ago. how much do you think native herps have changed in 12,000 years

[phil]

as to the last point. recent bird colonists include, the collared dove, little owl, great grey shrike,hoopoe, roller, honey buzzard and amongst many more bee-eater and more recently great eagle owl

[Killian]

Many species can and do adapt very well to this climate (as the members of this forum prove) I dont understand the point Phil is trying to make, are you suggesting that we should introduce all the species in Europe in to Britain? or are you saying that now that they are there they should be allowed to stay?

You do make a very valid point about the newts co-exhisting happily on the continent but there is a lot more space there for larger populations.

I live in ireland and we only have two native amphibians species (I think the frog was introduced incidentally) To be honest I wouldnt be in favor of introducing any more although I know it would do no harm.

[phil]

no killian i would not be in favour of the deliberate introduction of any more aliens. the point i was trying to make is that more fuss appears to be made over a few feral newts doing no harm at all, than the real reasons why several of our species are becoming rare. i went to puxton marsh in kidderminster a couple of years ago, to see if i could see some natrix. all i saw was about 5 cats, one of them with a slowworm dangling from its mouth. i think these are the aliens that need monitering more closely, not carnifex or alpestris or green and wall lizards.

[willj]

just to mention those of those birds you mention, roller is a rare vagrant, the bee-eater is becoming more common in this country with the occasional pair breeding, the little owl was introduced by the Victorians and the eagle owls were escapees from somewhere or other. the Great grey shrike has always been a winter visitor to our shores and a few pairs breed on the east coast every year. and the collared dove increased it's distribution in about half a centry due to a mutation.
the fact of the matter is that birds that are classed as "native" are all subdivided into categoreys. regular breeders, rare breeders and introduced. this is because there is a huge interest in birds, whilst unfortunately, there isn't for herps. you don't see herds of newt twitchers with nets after newts. and for that reason they aren't categorised like birds.

As for cats, i hater the b****rs too! but unfortunately there are too many of them to do anything about it.

as for monitoring alien species, you should be aware that they are put into two groups, naturalised and alien. both groups contain species that have been introduced by human interference. Aliens do damage to the enviroment, and naturalised species don't. Triturus carnifex is an alien. the newts interbreed with cristatus and dilute the gene pool. this could be disaterous if there is a population crash of cristatus in the country and all there are are hybrids. on another note ponds with marsh frogs in are found to have a decreased number of common frogs, with more established colonies having no common frogs in the pond. would you not say that is a matter for concern?

BTW Killian, i thought Ireland had three species, bufo calamita, L. vulgaris and R. temporaria? or is the natterjack only found in Southern Ireland?

[phil]

. dilution of a gene pool occurs where not enough non related adults of species breedtogether in isolation. we have the largest populations of cristatus in europe, when this does not occur anywhere where the ranges overlap in europe, i believe its a wild stab in the dark to suggest that because they are alien, they will behave differently

[willj]

just because they are common in britain doesn't mean we shoudn't be aware of the risks. true they are only found in a couple of sites, but still the risk is there and needs to be i dentified and removed. the only problem, is that local R&A groups fell proud to have these introductions on their lists.

[phil]

wouldn't introducing "new blood" only improve the gene pool. we are after all talking about 2 members of the super species cristatus. species divided to sub-specific level are not given full species status because they are not sufficiently different from the nominate type.and can only be identified by minor differences. i would agree with you if it was marmoratus, because the intergrades are not fertile with one another and can only breed with either of the parent species, thus causing genetic stagnation

[willj]

no introducing new blood is only enhances the gene pool if it is from the same species. and even then it usually has to come from a nearby population. adding a different species gene is genetic pollution. like when you go to the park and you see the different coloured and shaped mallard they my look pretty, but they pollute the natural gene pool. if this carries on then there are no truely wild birds. another example is the domestic cat causing the virtual extinction of pure wildcats in scotland.

[phil]

carnifex and cristatus are the same species just a different sub-species. adding genes from nearby populations is far more likely to cause pollution because the individuals are much more likely to be closely related. this is why populations of newts in an isolated location inhabitting only one or two ponds eventually die out. all healthy populations of cristatus have access to many breeding sites scattered over long distances. take for example, here in the north west we have the wigan pondway corridor stretching many miles containing thousands of ponds and thus we have a very healthy pop. of gcn. diversification is the answer not isolation in order to keep a healthy gene pool

[willj]

i think we've identified a problem here... cristatus, dobrogicus, karelinii and carnifex are no longer subspecies of cristatus. they are all seperate species.

you say that the populations can be diversified if new blood from different populations is added. I put it to you that in the short term this is correct, but in the long term it isn't. you need to "keep it in the family" to evolve all individiuals would become so similar that many alleles would be bred out and inidivuals would become to close to one another genetically and the species would die out. how else do you suppose dog breeders get new strains and breeds. and that chicken fanciers breed species with 8 foot long tails. besides, it's not our place to mix and match populations, as we could be mixing more than just populations, desease, especially with chytrid on the rampage is a major threat. it isn't as bad to mix a newt from shropshire with a newt from lincolnshire per say. but it's wrong to mix a newt from italy with a newt from Britain.

[phil]

have a look at this link dpc.uba.uva.nl/ctz/vol68/nr03/art04

[phil]

in this reply youv'e contradicted yourself. the reason dogs and other domestics come in all shapes and sizes is inbreeding certain traits over generaions and is often fraught with disaster. many breeds of dog suffer diseases and shorter lifespan because of this.the super species cristatus has in all its subspecies lived a trouble free existence along side and often intergrading with its near neighbours since long before certain taxonomists decided to sub divide and pointlessly confuse things even further. with , may i point out no genetic polution on the parent sub-species. if what you are saying is correct rana ridibunda and lessonae would no longer exist and we would only have esculenta