Gaboon and Rhino vipers

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Gaboon and Rhino vipers

Postby Bushviper » Tue Jul 29, 2008 1:38 pm

I know these are not all indigenous but I will post it here to illustrate my point. I have my doubts about B. gabonica not having a sub species. I have spoken to various experts in the field of taxonomy and not one could give me an answer that satisfies me. The definition of a species seems to be open to interpretation depending on what point they are trying to make.

Using the diagnostic tool of the size of the horn on the nose and the single or double marking under the eye I am trying to put these four specimens into two groups. It is not as easy as it seems.

I dont know what to make of this.
"East African" Gaboon viper. Bitis gabonica
Image
"East African" Gaboon viper Bitis gabonica
Image
"West African Gaboon viper" Rhinocerus viper Bitis rhinocerus
Image
"West African Gaboon viper" Rhinocerus viper Bitis rhinocerus
Image

It would make sense that any person looking at a snake should be able to identify it and as such know what to do with it. Kill it (if it is an alien invasive species) remove it (if it is dangerous) or get excited (if it is a rare species or in a new locality). To have to whip out its liver and send this off for analysis before making a decision does not make sense. Possibly to the scientists who "preserve wildlife" in bottles (like mongoose) instead of "conserve wildlife" in nature (like armata) this is fine but not to the rest of us non scientists.

I have also seen a snake with a teardrop on one side of the head but not on the other. This might not matter to the scientist who has access to his alcohol and DNA analysis but it is very very important to me when I am being arrested for owning a Threatened or Protected Species and am looking at potential jail time.
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Re: Gaboon and Rhino vipers

Postby BushSnake » Tue Jul 29, 2008 2:07 pm

Were all of the above shown species wild caught? If not, then I don't think you can draw up conclusions as to what subspecies/species they are. Many breeders (known or unknown) might cross west and east african subspecies to create morphs (or whatever you want to call them). If this is done, then no accurate ID can be made, not even by using DNA (correct me if I'm wrong).

And there are hundreds of cases in the insect world where species cannot be accurately identified using the external morphology, and either genetalia analysis or DNA analysis is required, so if it is needed for some snakes, then I definitely won't be surprised.
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Re: Gaboon and Rhino vipers

Postby Bushbaby » Tue Jul 29, 2008 2:10 pm

The last 2 were defenitly wild caught. The top possibly ranched or CH.
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Re: Gaboon and Rhino vipers

Postby froot » Tue Jul 29, 2008 2:53 pm

I don't think that they should be seperate species, subspecies maybe. My theory about them leans more towards the variation of a species over it's natural range.
How well are B. rhinocerus and B. gabonica geographically seperated?
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Re: Gaboon and Rhino vipers

Postby Boadicea » Tue Jul 29, 2008 3:14 pm

I beleive that the whole classification thing, even based on genetics, is pretty arbitrary. Species change location over time, they sometimes intermingle and share their DNA, they die out from certain areas and appear in others where they didn't occur before. Most of us just assume that things are always the way a minute few of us have perceived them to be. "Science' in my view does not describe ultimate truths - only imperfect human knowledge at best. The trouble comes in when they use it to create law.

A criminal act, BV, must be supported by criminal intention before you can be convicted of a crime. The average layperson does not walk around with the apparatus necessary for DNA testing and could not reasonably be expected to know whether or not a species is the protected one or not in the absence of external morphological evidence. I would imagine that unless you are caught in circumstances which clearly indicate that you ought reasonably to have possessed the necessary knowledge it would be difficult to secure a conviction.

Sadly however, if the law is an ass then those who are enforce it are usually the Baalam that rides it and therefore logic and reason do not always prevail as they should.
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Re: Gaboon and Rhino vipers

Postby Contortrix » Fri Aug 15, 2008 6:43 pm

The teardrop you are talking about.... one of my males have markings going past the eyes:

male with markings Image

And here is my other male without the markings.

No markings: Image

Here's allso a pic of my female she don't have any markings either...

Female: Image

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Re: Gaboon and Rhino vipers

Postby armata » Fri Aug 15, 2008 7:35 pm

The separation of western and eastern gaboons is based mainly on Lenk (2001) although Groombridge (1980) found seven synapomorphic characters states within the gabonica clade.

I think that the phlyogeography is important. Today there are no contact zones, i.e. the Dahomey gap (Benin). It would be of intereste to know the climatic history of the area - if at one time there was continous forest then maybe this supports the case for a variable species rather than two separate species.

I can think of another example - Vipera berus/nikolski. Some give V.nikolski full species status although there are contact zones and it hybridises with berus. However, the climatic history tells us that nikolski was well separated (isolated) in the past and only gradual warming has allowed it to expand its range. So, probably a true species, but perhaps a species in decline in the true sense.
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Re: Gaboon and Rhino vipers

Postby gaboon69 » Sat Aug 16, 2008 5:09 pm

Interesting BV.
I feel the same way about B.Cornuta.
I have seen specimens which differ so much in appearance that it is frightening.
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Re: Gaboon and Rhino vipers

Postby armata » Sat Aug 16, 2008 5:31 pm

@ gaboon 69 - when you say B.cornuta, do you mean the species complex, i.e. the five contained in the cornuta/inornata complex. If you mean just the single species B.cornuta then I agree that they are variable, colourwise and also degree of horn tufts.
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Re: Gaboon and Rhino vipers

Postby WW » Sat Aug 16, 2008 8:57 pm

Regarding rhinoceros and gabonica, the genetic evidence is pretty unambiguous: B. gabonica is remarkably uniform from KZN to all the way to Cameroon (e.g., a fraction of the genetic distance between a KZN and a Cameroon gabonica than between a De Hoop and an Oudtshoorn puffie), whereas B. rhinoceros is very distinct from all gabonica, in fact not much less distinct from B. gabonica than from B. nasicornis. Not proof positive beyond question (nothing ever is, least of all DNA evidence on its own), but highly suggestive, and pretty consistent with morphological evidence, oddball individuals notwithstanding.

BTW BV, you don't have to rip out the livers of anything for this line of work - buccal smears work just as well on snakes as on Saddam Hussein, and blood samples, scale clippings and fresh shed skins to the trick as well. And, if it came to the crunch, that DNA data would be the clearest way of avoiding you jailtime ;-)

Incidentally, it's a fairly typical pattern for African forest species, where the "Dahomey Gap" (where the W. African savanna reaches the coast in E. Ghana, Benin and Togo) represents the separation point between quite distinct eastern and western species pairs- e.g., Dendroaspis jamesoni and viridis, Pseudohaje goldi and nigra, etc.

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Re: Gaboon and Rhino vipers

Postby Bushviper » Sat Aug 16, 2008 9:19 pm

Thanks for the explanation WW. Why do so many scientists kill the specimens then? Is that just laziness?
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Re: Gaboon and Rhino vipers

Postby WW » Sun Aug 17, 2008 8:45 am

Bushviper wrote:Thanks for the explanation WW. Why do so many scientists kill the specimens then? Is that just laziness?


Hi BV - see my comments in the "pickling" thread - in some circumstances, you do need the body for other purposes.

Another issue is that my work has usually focussed on a few particular species with my own very specific aims, which often did not involve morphology, or where I was able to do the morphology under anesthesia. So far, I have not had too much cause to regret the lack of pickled vouchers from my studies (and since a lot of my samples come from collections whose owners would have removed parts of my anatomy before allowing me to remove any part of their snakes' anatomies, it often wasn't an option anyway). However, I have certainly had flak from colleagues about, in effect, hiding the evidence, or being selfish in not making it availabe to others. In more general herp collecting expeditions, the aim is to get the maximum of information out of every specimen, even if the specific investigator is not working on that species at that point in time, so bodies are collected with the samples, in case they later turn out to be needed for later taxonomic or other scientific work. It does result in a lot of dead pickles, and it's not something I would personally enjoy doing, but at the same time, but it is a tremendous source of information and one that my work has certainly benefitted from hugely at times. Whether the ends justify the means will depend on the extent of the collecting and everyone's personal views...

Cheers,

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Re: Gaboon and Rhino vipers

Postby gaboon69 » Mon Aug 18, 2008 12:38 pm

Was referring to the single species Armata.
Thank you.
Dont mean to hijack the thread so lets leave it there then.
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