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More Taricha toxicity questions

sde

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Hi all,

I have been wondering about this for a while, so I thought I would ask on here. I have read from a few sources that Taricha granulosa are more toxic than Taricha granulosa, does anyone know the validity of this?
Also, I have read more than once that T. granulosa are more toxic in northern Oregon populations, less toxic in Washington and California populations, and have very little or no toxin in Vancouver island BC populations. Could this be because of Thamnophis populations or something else?

Any and all help or comments are appreciated. -Seth
 

jAfFa CaKe

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Due to one of the tags being Taricha Torosa I assume thats what you meant? I was always under the impression T. granulosa is the most toxic newt on Earth.
 

sde

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I meant to say "I have read from a few sources that Taricha granulosa is more toxic than Taricha torosa, does anyone know the validity of this?"

I was always under the impression T. granulosa is the most toxic newt on Earth.

Yes so was I, but I just wanted confirmation. I am mainly interested in the second question I asked :)
 

caleb

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This paper:
http://faculty.virginia.edu/brodie/files/publications/JCE1999.pdf
found that T. granulosa from Vancouver Island had no detectable tetrodotoxin (TTX), and that TTX levels varied widely between populations.

They suggested that TTX levels in T. granulosa are highest where snakes have high TTX resistance, and lowest where snakes have low TTX resistance- they described it as an 'arms race' between newts and snakes.

It does seem that the most toxic granulosa contain more TTX than the most toxic torosa- but given that some granulosa have no TTX at all, clearly some torosa are more toxic than some granulosa.

This paper:
http://www.mdpi.com/1660-3397/8/3/577/pdf
gives a summary of TTX levels in various amphibians, and yes, T. granulosa comes out on top.
 
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sde

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Thanks Caleb!

These are awesome papers, very good detailed information.

My questions have been answered...
 

FrogEyes

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TTX is also probably produced by microorganisms, and sequestered by the toxic animal. As for poison frogs, the variation in toxicity may be highly influenced by the local diet. The snakes' ability to eat the newts likely evolves rapidly from a single gene, and will really only take place where the resistance is useful. This is true for a diet of slugs, as a single gene in Thamnophis elegans tells the snake that slugs [and leeches] are edible, but that gene variant is absent in areas where predatory leeches are present. This means that the snakes only eat slugs and leeches in places where they are not at risk of the leech feeding internally. So if the bacteria are present and contribute to the newt diet, the newt will be toxic, local snakes will either not eat them or will quickly have resistance spread in the population.
 

sde

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Thanks FrogEyes, interesting stuff. I had read previously that Taricha species probably make their own toxin, so that correction was quite useful.
So if a T. elegans population does not eat slugs then that means there are parasitic leeches? Interesting.

So if the bacteria are present and contribute to the newt diet, the newt will be toxic, local snakes will either not eat them or will quickly have resistance spread in the population.

When you say the "bacteria" are you talking about the microorganisms that produce the TTX? So how do the newts ingest them in the first place? Via food items? And then once they are in the newt they ( and/or the toxin ) are sequestered? Am I understanding correctly?
 

MarioR

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TTX is also probably produced by microorganisms, and sequestered by the toxic animal. As for poison frogs, the variation in toxicity may be highly influenced by the local diet.

We are working on both theories right now.
Further knowledge will be available next year both for Taricha granulosa and Notophthalmus viridescens. But we need offspring of wild caught animals first.

kind regards,
Mario
 

tyzoone

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So let me see if this novice can translate you smart peoples wordses. So the toxicity of the T grans could possibly be all diet based or based on locale alone? I've actually been concerned about this for a while now since my one T gran escaped (which I later found alive). I have a toddler and a 5 month old that I worry about. I was specifically wondering what kind of danger are my kids really in having these newts in the house? Can the toxin be transferred just by having my hand in the water or is it something emitted when they are being threatened or chewed on? I now have a lid for my tank but would it be smart to have some kind of lock on it to keep the minions out? Is there a non-threatening test kit available to find out if my newts have the toxin or what level it's at?
 

Azhael

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Your newts have the toxin, it's how much of it that's the question. For this species, however, i don't think there are any populations that wouldn't be life threatening to small children, so yes, take as many steps as necessary to guarantee that everybody in your house is definitely safe.
The toxic is exuded in large quantities when the animal is threatened or injured and it is visible as a milky, foul smelling liquid, generally appearing in droplets over the newt's skin. Mind you, there is always going to be some residue on the skin, visible or not, and if you must manipulate one for whatever reason, you should inmediately was your hands thoroughly and make sure not to have any open wounds or allow contact with any mucoses.
 

sde

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It is wise to wash your after you touch a Taricha directly, or if you just put your hands in the water. Better to be safe than sorry.
What FrogEyes said is that food it is not believed to be the source of toxin in Taricha species, but it is thought to be the source of toxin in poison frogs. However the toxicity of Taricha does apparently depend on the locale Thamnophis population. -Seth
 

mitchelljs

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Regardless of the source of the toxin in Taricha (although I strongly suspect the newts produce it, rather than acquire it), the resistance in the garter snakes is definitely evolved. This is actually an example of what's called the Red Queen Effect. These sorts of arms races occur quite often with venomous/toxic prey and their predators (for instance, opossum populations vary in their resistance to viper venoms, for instance, as a function of how many rattlesnakes are in the area).
 
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