ADVERTISEMENT
  About the SA Blog Network













Tetrapod Zoology

Tetrapod Zoology


Amphibians, reptiles, birds and mammals - living and extinct
Tetrapod Zoology Home

33% of the newts of my country

The views expressed are those of the author and are not necessarily those of Scientific American.


Email   PrintPrint



Male German Palmate newt, image by Christian Fischer, licensed under Creative Commons Attribution-Share Alike 3.0 Unported license.

I know the newts of my country… but that’s not hard, there are only three (or four if you count the alien one). The Palmate newt Lissotriton helveticus is Britain’s smallest species (reaching 95 mm in total length), though it’s not the smallest of all European newts, being exceeded by the 80 mm Italian newt L. italicus. Actually, though, there are some English Palmate newt populations that consist of genuine dwarfs: individuals that are just 51-60 mm long in total. Beebee & Griffiths (2000) say that adult animals on Jersey are even tinier. There’s a predictable joke here about tiny newts but I can’t remember what it is. [Image above by Christian Fischer.]

NOT a Palmate newt: a male Smooth newt. Note obviously spotted underside and lack of terminal tail filament. Photo by Darren Naish. CC BY.

Anyway, the Palmate newt is endemic to western Europe. Ireland lucks out, as does central and southern Portugal and Spain. Like most or all newts, its diet is basically determined by whatever it can cram down its throat. During its aquatic phase, the Palmate preys extensively on crustaceans while terrestrial individuals mostly eat springtails and soil mites (Beebee & Griffiths 2000).

Breeding male Palmate newts possess a very low, unserrated crest and possess black webbing on the hind feet and a filament at the tail-tip. As is typical for the crested salamandrids, males display to females by fanning and whipping their tails, wafting pheromones over females in the hope that they will follow and accept a spermatophore packet. Ridges that run along the male’s body seemingly help channel the pheromones along his length and it has also been suggested that the peculiar filament at the tail tip helps reduced turbulence during the fanning display: somebody should study this. Female Palmates are often hard to distinguish from female Smooth or common newts L. vulgaris but have a pale bar above the hindlimbs and a pinkish, unspotted throat.

So much more to say, but out of time. Much more on salamanders soon.

For previous Tet Zoo articles on salamanders, see…

Refs – -

Beebee, T. & Griffiths, R. 2000. Amphibians and Reptiles. HarperCollins, London.

Darren Naish About the Author: Darren Naish is a science writer, technical editor and palaeozoologist (affiliated with the University of Southampton, UK). He mostly works on Cretaceous dinosaurs and pterosaurs but has an avid interest in all things tetrapod. His publications can be downloaded at darrennaish.wordpress.com. He has been blogging at Tetrapod Zoology since 2006. Check out the Tet Zoo podcast at tetzoo.com! Follow on Twitter @TetZoo.

The views expressed are those of the author and are not necessarily those of Scientific American.



Previous: Fantastic asses More
Tetrapod Zoology
Next: Tale of the Takydromus




Rights & Permissions

Comments 48 Comments

Add Comment
  1. 1. BrianL 10:46 am 09/9/2013

    My parents used to have some of these lovely critters in their pond (along with *Triturus cristatus*, *Ichthyosaura alpestris* and *L. vulgaris*), but not anymore it seems.

    That being said, *L. helveticus* is known to hybridise with *L. vulgaris*, as you said the females look very much alike and some of the *vulgaris* among the population have a slight filament at their tail end, so there is the possibility of some *helveticus* strain remaining in what are mostly *vulgaris* individuals. Is hybridisation the likely cause for the occurence of the filament in what otherwise seem like typical *vulgaris* specimens or does the trait occasionally occur in some *vulgaris* as well?

    Link to this
  2. 2. llewelly 10:58 am 09/9/2013

    I guess all those glaciations in the Pleistocene were not good for newt diversity.

    Most of Britain was covered by the most recent glaciation, and the rest of Britain cannot have been good newt habitat.

    (Although, isn’t there a Siberian toad that can survive being frozen for several years? hm … )

    Link to this
  3. 3. BrianL 11:45 am 09/9/2013

    @llewely:
    Glaciations in Europe were not good for fauna (and presumably flora) in general. Up until earliest Pleistocene times, Europe had a fauna once could describe as ‘Ethiopean’ + more.

    For herps, glaciation presumably meant the loss of not just many species in surviving clades, but the complete loss of giant salamanders, monitor lizards, crocodilians, snapping turtles and presumably hosts of others that I, not being all that wellversed in herps, am undoubtedly forgetting.

    Link to this
  4. 4. vdinets 1:10 pm 09/9/2013

    llewelly: that’s a Hynobiid salamander, not a toad. There were claims that some individuals were successfully revived after being found in Pleistocene permafrost layers, but AFAIK nobody knows for sure how long this species can survive being frozen.

    Link to this
  5. 5. Kunokephalos 4:46 pm 09/9/2013

    Why have you got a tiny amphibian in your pocket?
    Because it’s my newt.

    Ithankyou.

    Link to this
  6. 6. naishd 3:26 am 09/10/2013

    BrianL: yes, Smooth x Palmate newt hybirds are known and do possess a combination of traits, and Smooth newts to do not ever possess a terminal tail filament. Are you sure the individuals aren’t female Palmates?

    As for glaciation and the British herpetofauna… yes, the only taxa able to hang on here were the most cold-tolerant (even though Britain did not become completely glaciated: ice ‘only’ got as far south as the Severn-Thames line). Hence we have a sort of Scandivanian assemblage more than a Central European one.

    Darren

    Link to this
  7. 7. BrianL 4:15 am 09/10/2013

    @Darren:
    Well, that could work for females which are, as you said before, somewhat difficult to distinguish from each other between the species. However, the tail filament also occurs in some male individuals that look like normal *vulgaris* otherwise. The devil might be in the detail here, though, so if these are indeed males of hybrid origin, they may also possess other *helveticus* traits that are far more subtle than the rather obvious tail filament. In any case, I would suspect that any such hybrids would be ‘mostly’ *vulgaris* with only very limited *helveticus* bloodline left. The *helveticus* always were far outnumbered by the *vulgaris* and, unless those females count, my parents haven’t seen any in at least 15 years or so.

    Link to this
  8. 8. naishd 4:27 am 09/10/2013

    Waitaminute… I knew that Smooth x Palmate hybrids are on record, but I had forgotten how rare they are. Beebee & Griffith (2000) say…

    “Given the uncertainties involved with courtship and the similarities in the displays of smooth and palmate newts it is perhaps surprising that hybrids are almost unknown even in ponds where the two species coexist. Although it has been possible to produce such hybrids under laboratory conditions for many years (e.g. Spurway & Callan, 1960), the first natural specimen (a male, Fig. 14) was not found until 1984 (Griffith et al. 1987). Analysis of the chromosomes of this individual showed that it was the offspring of a male palmate and female smooth. It was ten years before more hybrids came to light, this time from ponds in France, the Netherlands and southern England. Genetic analysis of very large samples has confirmed that hybridisation between these species is extremely rare (Arntzen et al., 1998).” (p. 58).

    So, you _might_ have been looking at hybrids – but, if you were, it could have been something of a big deal. A hybrid individual pictured in Beebee & Griffiths looks much like a normal breeding male Smooth newt, but it has a tail-tip filament and more toe webbing that is normal for a Smooth.

    Darren

    Link to this
  9. 9. David Marjanović 9:22 am 09/10/2013

    For herps, glaciation presumably meant the loss of not just many species in surviving clades, but the complete loss of giant salamanders, monitor lizards, crocodilians, snapping turtles and presumably hosts of others that I, not being all that wellversed in herps, am undoubtedly forgetting.

    Albanerpetontids; hynobiid salamanders; close relatives of Tylototriton and Echinotriton; plethodontid salamanders (now limited to caves south of the Alps); palaeobatrachid frogs (like pipids, only European, with a history that stretches deep into the Cretaceous); and on the amniote side, choristoderes.

    That’s probably still not a complete list.

    Link to this
  10. 10. Heteromeles 4:51 pm 09/10/2013

    Although it probably doesn’t affect the herps as much as the larger animals, I’d suggest it’s not just glaciation, it’s glaciation plus the neolithic that really changed things in Europe.

    Link to this
  11. 11. Heteromeles 4:54 pm 09/10/2013

    By the way, is this all the British newts that’s fit to print?

    Link to this
  12. 12. vdinets 5:42 pm 09/10/2013

    David: did choristoderes really survive until the glaciations? If so, why aren’t they mentioned in cryptozoological literature? Some of them reached 3 m in length even before the Pleistocene. Isn’t it totally plausible that their way of rapidly adapting to the cooling climate was to become even larger and develop endothermy in some novel way that involved fire-breathing as a byproduct?

    Link to this
  13. 13. Dartian 1:49 am 09/11/2013

    Strictly speaking it’s not quite right to say that choristoderans and crocodylians were wiped out from Europe by the glaciations; AFAWK they had gone extinct already a few million years before that. (Granted, in all likelihood that happened because of climatic detoriation – but the real ice ages wouldn’t begin until much later.) The last known European choristoderan, Lazarussuchus inexpectatus, is from the early Miocene (Evans & Klembara, 2005). And the last known European crocodyliform (if we ignore the anecdotal reports of vagrant crocodiles in the Mediterranean region in historical times) is from the early Pliocene, ca. 5-6 MYA (Delfino et al., 2007).

    References:
    Delfino, M., Böhme, M. & Rook, L. 2007. First European evidence for transcontinental dispersal of Crocodylus (Late Neogene of southern Italy). Zoological Journal of the Linnean Society 149, 293-307.

    Evans, S.E. & Klembara, J. 2005. A choristoderan reptile (Reptilia: Diapsida) from the Lower Miocene of Northwest Bohemia (Czech Republic). Journal of Vertebrate Paleontology 25, 171-184.

    Link to this
  14. 14. naishd 4:19 am 09/11/2013

    Heteromeles (comment # 10): the Neolithic may indeed have changed things as goes diversity of herps across Europe, but I suppose the point in this discussion is that glaciation across the north extinguished various lineages before humans made an impact. Actually though, it is worth discussing both factors, since – here in Britain, at least – we do think that some species were probably made extinct by human agency. The Moor frog Rana arvalis (a member of the brown frog group) and Pool frog Pelophylax lessonae (a member of the Western Palaearctic water frog complex) both survived in England until historic times, for example, and some people think that the Green tree frog Hyla arborea did as well. Actually, there have also been informal (and, I think, unpublished) suggestions that Western green lizards Lacerta bilineata, Asps Vipera aspis and Dice snake Natrix tessellata might have hung on too.

    In fact, there are various species that we _should_ have in the UK but apparently don’t: Alpine newt Ichthyosaura alpestris and Green toad Pseudepidalea viridis, I’m looking at you (though we do now have the Alpine newt here as an alien).

    Some of this stuff has been covered on Tet Zoo before, let me add some links…

    Darren

    Link to this
  15. 15. naishd 4:27 am 09/11/2013

    Ok, here we go…

    Hunting Green lizards in Dorset: new aliens or old natives?
    Britain’s lost tree frogs: sigh, not another ‘neglected native’
    In pursuit of Romanian frogs (part II: WESTERN PALAEARCTIC WATER FROGS!!)
    In pursuit of Romanian frogs (part III: brown frogs)

    Darren

    Link to this
  16. 16. David Marjanović 7:30 am 09/11/2013

    did choristoderes really survive until the glaciations?

    Maybe not, but their fossil record is extremely spotty, so I wouldn’t be surprised if mid-Pliocene ones showed up one day…

    Isn’t it totally plausible that their way of rapidly adapting to the cooling climate was to become even larger and develop endothermy in some novel way that involved fire-breathing as a byproduct?

    You win this thread.

    Link to this
  17. 17. naishd 9:39 am 09/11/2013

    Yeah.. on cryptozoology and choristoderes (see comment # 12): actually, some of the accounts of weird European and Asian ‘crocodiles’ and ‘lizards’ in the cryptozoological and fortean literature are vague enough that some cryptozoologists have indeed suggested that they might be references to surviving choristoderes. This doesn’t mean anything though. After all, there are cryptozoologists who have also supported the existence of merbeings, the persistence of bonytoothed birds, teratorns, archaeocetes, tanystropheids, glyptodonts, eurypterids, trilobites and about everything else that ever walked, flew, swam or crawled.

    Having mentioned cryptozoology (something on my mind a lot due both to our ongoing work on the Cryptozoologicon, and my current reading of Loxton & Prothero’s Abominable Science), let us not forget the brilliant idea that the Loch Ness Monster is actually a gigantic newt. There’s one eyewitness account that refers to the presence of a bright orange underside the creature. Case closed. Definitely a gigantic newt.

    Darren

    Link to this
  18. 18. Dartian 11:41 am 09/11/2013

    This is perhaps OT but it’s at least (very) marginally related to what we’re discussing in this thread – and the images are just too fucking awesome not to share:

    The European crocodyliforms might as well consider themselves lucky that they went extinct before the Pleistocene. In the Pleistocene, there were jaguars in Europe. And, if the European jaguars were anything like their extant Neotropical kin, this is what they would have done to the poor crocodylians.

    Link to this
  19. 19. naishd 12:16 pm 09/11/2013

    Those jaguar vs caiman photos are incredible… proof that cats are aquatic ambush predators of terrestrial crocodylians :)

    And that particular cat clearly knew _exactly_ what he was doing.

    Darren

    Link to this
  20. 20. Jerzy v. 3.0. 6:38 pm 09/11/2013

    @14
    I think it goes both ways. Local historical population of herps is S England could gone extinct before being noticed by zoologists. Others could be introduced historically but now regarded as natural.

    Odd pattern of occurrence of shrews and rodents on small islands around Britain is now seen as a result of old introductions. I see no reason why amphibians, reptiles and all other small fauna and flora were not similarly transported?

    Link to this
  21. 21. Jerzy v. 3.0. 6:39 pm 09/11/2013

    Cool jaguar photos, BTW!

    Link to this
  22. 22. naishd 6:54 pm 09/11/2013

    On British herptile populations, Jerzy says (comment # 20) “Local historical population of herps is S England could gone extinct before being noticed by zoologists. Others could be introduced historically but now regarded as natural.”

    Hypothetically, you could be right about the local extinctions (though, I emphasise the ‘hypothetically’. The fossil, archaeological, and modern records do generally agree on which species we do, and do not, have).

    As for human agency as an introduction mechanism, I agree that this is theoretically plausible – - but does it apply in practise? For the shrews and rodents you have in mind, we have genetic and cultural evidence pointing to good ‘trails of introduction’ (and, in cases [e.g., the Orkney voles on Steep Holm] even the testimony of people involved in the introductions). Do we have this for the amphibians and reptiles? Well, which ones are you thinking of? The evidence at the moment points to some of the species concerned being relicts of an original north European distribution (e.g., Pool frog, and perhaps Green tree frog and European pond terrapin) while others are surely recent (20th Century) introductions, not old ones (e.g., Western green lizard, Italian wall lizard, Alpine newt, Midwife toad).

    Darren

    Link to this
  23. 23. Dartian 11:41 pm 09/11/2013

    Darren:
    And that particular cat clearly knew _exactly_ what he was doing.

    Indeed. Total determination. Very, very impressive.

    There are more pictures of the same event on National Geographic’s webpage. There we also learn that this particular male jaguar has been given a name, Mick Jaguar. :)

    Link to this
  24. 24. llewelly 1:14 am 09/12/2013

    ” Isn’t it totally plausible that their way of rapidly adapting to the cooling climate was to become even larger and develop endothermy in some novel way that involved fire-breathing as a byproduct?”

    no, no, the fire-breathing was a byproduct of lighter-than-air flight …

    Link to this
  25. 25. llewelly 2:10 am 09/12/2013

    By the way, one motivation for my comment about glaciation was the relatively narrow window between the post glaciation warming and formation of the English channel, which seems to me to have been very effective at preventing herps from re-colonizing Britain. And Ireland has even fewer native herps, I think. (This actually comes up, along with the Scandanavian rule of thumb for British herps, in one of the linked older tetzoo herp articles.)

    “Yeah.. on cryptozoology and choristoderes (see comment # 12): actually, some of the accounts of weird European and Asian ‘crocodiles’ and ‘lizards’ in the cryptozoological and fortean literature are vague enough that some cryptozoologists have indeed suggested that they might be references to surviving choristoderes.”

    Hah. Imagine Nessie as a late-surviving Hyphalosaurus whose size has been somewhat exaggerated. : )

    Link to this
  26. 26. Chabier G. 7:10 am 09/12/2013

    Palmate newt has been wiped out by Louisiana Red Crayfish in the Ebro Valley, after the demographic boom of this crustacean in the 90′s. Otherwise, Marbled Newt is still common, I think it´s because the latter species relies mostly on temporary ponds to spawn. The last palmated newt I saw here was sharing a pit with a red crayfish, the poor amphibian lacked jaws and a forearm.

    Link to this
  27. 27. David Marjanović 7:31 am 09/12/2013

    And Ireland has even fewer native herps, I think.

    Fun fact: Ireland lacked snakes even before St. Patrick arrived.

    Link to this
  28. 28. Yodelling Cyclist 9:59 am 09/12/2013

    no, no, the fire-breathing was a byproduct of lighter-than-air flight …

    Please, please don’t encourage the crazy people.

    Link to this
  29. 29. SRPlant 1:02 pm 09/12/2013

    #27
    “Fun fact: Ireland lacked snakes even before St. Patrick arrived.”

    Tell that to the Irish Dodo;
    http://pomposa.livejournal.com/16511.html

    Link to this
  30. 30. Jerzy v. 3.0. 5:37 pm 09/12/2013

    @22
    In Continental Europe eg. botanists understand that humans carried plants around (not just obvious medicinal or weed species, but many others) and many isolated populations of plants are likely ancient introductions.

    For reptiles and amphibians, there is lots of old records of isolated populations in again mainlaind Europe, which were wiped out historically.

    It would be strange if transports in historic times carried incidentally only rodents and plants, but not other groups, isn’t it? And if every population in Britain was well documented isn’t it? I guess there are old records of herps in Briatian which are in grey zone – nobody is sure how certain they are.

    This is one minor interest of mine. Recognizing that historic records of fauna are, by definition, full of omissions. And that fauna was influenced by man much more and earlier than generally believed.

    I will not argue that certainly eg. tree frog was native to Britain. I see this more like recognizing the grey area of uncertainity here.

    Link to this
  31. 31. llewelly 9:07 pm 09/12/2013

    “This is one minor interest of mine. Recognizing that historic records of fauna are, by definition, full of omissions. And that fauna was influenced by man much more and earlier than generally believed.”

    vdinets, that is very interesting.

    To the best of my admittedly amatuerish knowledge, nearly all archaeologists and anthropologists agree that that deliberate starting of large landscape fires played a vital role in human management of both game and edible plants, all the way back to the earliest homo sapiens . (Some argue it goes back to home erectus .)

    This is sometimes theorized to have played a large role in the end-Pleistocene megafauna extinctions.

    Surely these fires must have had substantial effects on herps?

    Link to this
  32. 32. llewelly 9:08 pm 09/12/2013

    uh, my apologies for fumbling both Homo erectus and Homo sapiens .

    Link to this
  33. 33. Dartian 1:14 am 09/13/2013

    Jerzy:
    It would be strange if transports in historic times carried incidentally only rodents and plants, but not other groups, isn’t it?

    Not necessarily. Not all organisms are equally well suited for being transported over long distances by pre-industrial age humans. Rats, mice and, to a lesser extent, voles travel well, as do plants (or rather, their seeds). Amphibians, on the other hand, do not. They are relatively fragile, don’t tolerate saltwater, and are very vulnerable to desiccation. In other words, they are unlikely candidates for having survived (say) a boat trip from continental Europe to Britain as stowaways in ancient times.

    Of course, in principle at least it’s possible that they might have been transported by humans on purpose. But people usually only do this to animals that serve as important food items or are otherwise culturally significant. And I don’t think it’s likely that ancient humans would have taken the trouble to translocate frogs and toads – never mind newts – across Europe just to eat them.

    Llewelly:
    uh, my apologies for fumbling both Homo erectus and Homo sapiens.”

    You also fumbled by mis-reading whose comment you replied to. Dude, this clearly isn’t your day. ;)

    Link to this
  34. 34. David Marjanović 6:22 am 09/13/2013

    Tell that to the Irish Dodo;
    http://pomposa.livejournal.com/16511.html

    Awesomeness.

    Link to this
  35. 35. Heteromeles 9:46 am 09/13/2013

    Perhaps these, erm, extirpated crocodilians were transported during historic times?

    Link to this
  36. 36. vdinets 12:39 pm 09/13/2013

    I can easily imagine the French (or the Normans who had lived in France for centuries) transporting frogs for food. Amphibians could also get onboard in drinking water containers (as adults, tadpoles or eggs), and then be carried upstream to river ports. But in this case their introduced populations would be centered around major port cities. You can see this pattern in introduced populations of greenhouse frog and Puerto Rican coqui in the US, and in the distribution of certain gecko species worldwide.

    Link to this
  37. 37. Jerzy v. 3.0. 2:57 pm 09/13/2013

    Actually, juvenile newts, toads and lizards in Europe are often transported with bulk products like vegetables, timber etc.

    They are much better candidates for human-mediated dispersal that e.g. the pygmy shrew with it’s great food demands – which colonized Ireland being carried by man.
    http://www.ncbi.nlm.nih.gov/pubmed/21673740

    Link to this
  38. 38. Dartian 11:49 pm 09/13/2013

    Jerzy:
    juvenile newts, toads and lizards in Europe are often transported with bulk products like vegetables, timber etc.

    We weren’t talking about lizards. They are not amphibians.

    More importantly, however, we weren’t talking about modern times – this was about introductions that took place long ago (I specifically said “pre-industrial age” in comment #33). Back when there weren’t airplanes, express trains, 18-wheeler trucks, etc., or refrigerators and thermostats to keep the cargo suitably moist and suitably cool. Back when travelling to another country was a major undertaking that took considerably longer than just a couple of hours or so. In this regard the situation today is simply not comparable to the Middle Ages, the Viking Age, or the times of Ancient Roman.

    Link to this
  39. 39. Dartian 11:53 pm 09/13/2013

    …and I meant of course Ancient Rome, not Ancient Roman.

    Link to this
  40. 40. vdinets 5:17 am 09/14/2013

    Dartian: replica Viking boats have exceeded 8 knots, and covered more than 400 km per day (see Wiki article on longship). The English Channel is just 33 km wide.

    Link to this
  41. 41. Jerzy v. 3.0. 8:51 am 09/14/2013

    Dartian,

    There was thriving trade across the English Channel at least from Roman times onwards.
    Go here and here.

    Link to this
  42. 42. Dartian 10:33 am 09/14/2013

    replica Viking boats have exceeded 8 knots</i"

    I'll take your word for it. But what does that have to do with the question of dispersal of amphibians to the British Isles in pre-industrial times?

    "and covered more than 400 km per day

    Ah, you’re trying to suggest that the Vikings could have brought frogs and newts over to the British Isles. In that case, please provide to this discussion the more relevant data on how long it actually took for the real Vikings and their non-replica boats to cross from Scandinavia to the British Isles – keeping in mind that there’s more to a sea voyage than just the actual crossing of the sea. (Hint: The ships would also have to be loaded as well as unloaded. The time that that took would need to be factored in here.)

    The English Channel is just 33 km wide.

    I think you’re confusing the Norman Conquest with the Viking Age. The Normans were admittedly residing in modern-day France and were (at least partly) the descendants of Vikings. But AFAIK frogs and newts were not an important part of their diet.

    Link to this
  43. 43. Jerzy v. 3.0. 11:43 am 09/14/2013

    Hi Dartian,

    My previous post somehow disappeared. Yes, there is intensive trade across the English Channel at least from the Roman times (1. century AD):
    Go here and here on wikipedia.

    And yes, crossing from France to Britain takes just a few hours even for a slow merchant boat.

    Link to this
  44. 44. naishd 12:04 pm 09/14/2013

    I’m very confused as to where this discussion is going. British native amphibians and reptiles (some of which are now extinct) are of the sort present in Scandinavia, and seem from the archaeological/fossil record to have been present in the UK for an extended period… so, not sure why we’re talking about crossing times from France. While I still don’t agree that reptiles and/or amphibians would be readily transported accidentally by boat (shrews and rodents are, of course, very readily transported in animal feed), water frogs have seemingly been transported widely as food items. Nevertheless, such a use does not well explain the Scandinavian-type Pool frogs previously present in England (and now re-introduced).

    When putting links into a post, the SciAm system quarantines any comment with more than one or two (mostly. It’s temperamental).

    Darren

    Link to this
  45. 45. Dartian 12:41 pm 09/14/2013

    Darren:
    I’m very confused as to where this discussion is going.

    Frankly, it seems to be going nowhere, and going there fast. (In retrospect, I realise that I probably shouldn’t have even bothered taking part in it.) This discussion is about speculative what if-scenarios that currently aren’t supported by any real evidence one way or the other.

    Link to this
  46. 46. vdinets 9:55 pm 09/14/2013

    I am not saying that any herps were or weren’t introduced to England. Such claims can only be made if there is solid historic record or molecular data. I am simply pointing out that pre-modern introductions weren’t impossible and that travel times were not an issue. It probably took a Norse sheep about a week to sail from southern Norway to northern England. A bunch of tadpoles could easily be transported in a water container, and then thrown out as the ship entered a river.

    Link to this
  47. 47. vdinets 10:02 pm 09/14/2013

    I mean ship, not sheep, obviously.

    Link to this
  48. 48. Hai~Ren 11:13 am 09/15/2013

    My pet hypothesis: From a Southeast Asian perspective, I have a feeling that some amphibians in this region could have dispersed with the help of humans. There are a number of frogs and toads that are widespread throughout Southeast Asia, but are rare or absent in tropical rainforest (the predominant original habitat), or limited to forest edges. Today, these species are often seen as semi-commensal, are common in and around inhabited areas, and live in habitats that were formerly absent until in recent history, such as open marshland, rural ditches and streams, and rice fields.
    I think that as wet rice cultivation spread down into Southeast Asia, it’s possible that these amphibians, native to more open habitats further north in Indochina, followed the trail of deforestation into the Malay Peninsula and the islands of Sumatra, Java, and Borneo, or were accidentally transported into these new areas; rural aquaculture probably also played a role in creating habitat for these open-country species. And because islands are often situated very close to the mainland, these frogs and toads were able to colonise them as well (probably also helps that these species are often found near the coast and are tolerant of slightly brackish conditions).
    It seems as if the same process could have occurred (and is still occurring) in several other groups, such as freshwater fishes (large riverine species from Indochina introduced for food, small species introduced incidentally with fry and fingerlings of large species), freshwater shrimp, and freshwater molluscs like bivalves and snails.

    Link to this

Add a Comment
You must sign in or register as a ScientificAmerican.com member to submit a comment.

More from Scientific American

Scientific American Back To School

Back to School Sale!

12 Digital Issues + 4 Years of Archive Access just $19.99

Order Now >

X

Email this Article



This function is currently unavailable

X