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question about venomous diversity
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by bush_viper17 on August 12, 2005
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I have been wondering why the Americas don't have as many elapids as the the eastern world(africa,asia etc.) I know that the eastern world has just as many if not more pit vipers but the Americas elapids are basically all coral snake subspecies. Does anyone know why the Americas dont have as many elapids as other parts of the world? Thanks.
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RE: question about venomous diversity
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by earthguy on August 12, 2005
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Not to be sarcastic (which I usually am), but you may as well ask "Why don't elephants live in the US?". It's just a matter of natural selection. The pit vipers simply grabbed a tight hold to their general nich and the elapids specialized (bear in mind that elapids and pit vipes are not mutually exclusive). I don't think that they are major competitors. If I run across anything more specific, I'll let you know.
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RE: question about venomous diversity
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by bush_viper17 on August 12, 2005
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No, I was hoping someone would tell me some theories. Well, I guess it was a stupid question, but someone may have an answer and it is still up for anyone who may know.
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RE: question about venomous diversity
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by Chance on August 12, 2005
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I'm sure it mostly just has to do with continential drift over the past number of millions of years, and the fact that the western hemisphere broke off from the eastern hemisphere with only a small number of elapids present. If you like at places like Australia, the same sort of situation exists only with the obvious difference that Australia has no viperids, only elapids, pythons, colubrids, and blind snakes. You can also look at places like Ireland which could ecologically support snakes, but have no native species. It all just depends on if a snake species could establish itself there before the land masses separated. You never know, if we don't destroy the planet before it could happen, the land now known as Antarctica could move toward the equator, bump into Australia or South America along the way, and form an entirely new group of snakes/herps over the next few million years. Too bad we can't take a glimpse into the future to find out.
-Chance
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RE: question about venomous diversity
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by Buzztail1 on August 12, 2005
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There is nothing wrong with asking for theories.
It is probably just a topic that not many people have put a lot of thought into.
My own personal belief is that snakes fill individual niches in the existing ecological areas. The "new world" has an amazing diversity of "colubrid snakes" whose niche or similar place in the ecosystem in the "old world" is often filled by elapids.
In general, old world elapids hunt their food and act much in the same way as our (US) colubrids.
I offer rat snakes (lately Pantherophis) and racers (Coluber) as my initial examples of "new world" colubrids filling the same niche as "old world" elapids such as mambas, etc.
Just a personal theory, without a single shred of researched evidence towards the "true answer".
Karl H. Betz
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RE: question about venomous diversity
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by GREGLONGHURST on August 12, 2005
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You never know, if we don't destroy the planet before it could happen, the land now known as Antarctica could move toward the equator, bump into Australia or South America along the way, and form an entirely new group of snakes/herps over the next few million years. Too bad we can't take a glimpse into the future to find out.
Chance: Despite your fears, we could not destroy this planet if we tried.
~~Greg~~
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RE: question about venomous diversity
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by bush_viper17 on August 12, 2005
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Thanks everyone for your point of view. I have always thought that it is amazing how animals live and adapt throughout the world.
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RE: question about venomous diversity
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by Chance on August 12, 2005
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Greg, you are of course right. I guess my sarcasm/witticism didn't go through very well. I should've said, "If we don't destroy all life on this planet before then" or something to that effect. No, destroying the entire planet would certainly be a feat I would hope we could not accomplish anytime soon....
-Chance
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RE: question about venomous diversity
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by CAISSACA on August 16, 2005
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Two points to the original question:
First, the Americas have a very large number of SPECIES of elapid - 68 according to the EMBL databse, roughly the same as Africa and Asia combined! The difference, of course, is that they are all coral snakes, only two genera, so in terms of morphological and ecological diversity, the New World elapid fauna is indeed less rich than its Old World counterparts.
Second, a lot of what we see in terms of diversity pattern has little to do selection or other deterministic processes, and everything to do with historical contingency (or, in plan terms, pot luck!). The Americas have a lot of coral snakes and no other elapids because at a past time of warmer climate, a coral snake, and no other elapid, made it across a land bridge occupying the present-day Bering Strait, and then diversified in the Americas. Had that snake been a cobra, then there might be a variety of cobras in the Americas, and no coral snakes.
Why the coral snakes did not diversify more after they occupied the Americas is another question - possible answers could include phylogenetic constraint (basically, they were stuck with being coral snakes), or indeed competition from other organisms. If coral snakes are well adapted to the ecological niche they occupy, then there will be selection against those that try to leave it by acquiring different morphological characters especially if that puts them in cmpetition with other rganisms occupying other niches.
Just a few thoughts...
Cheers,
WW
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RE: question about venomous diversity
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by bush_viper17 on August 18, 2005
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Thanks WG. Your answers are always knowledgable and I have learned alot from reading your posts/replies and from your website. Again, thanks for the reply.
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