# why do certain species have certain toxins?



## dom (Sep 23, 2007)

Does anyone know of any research done on why certain species evolved different toxins.

For instance do Phyllobates terriblis produce batrachotoxin because of the their diet, or is it from genetics? I know there are studies on diets of different poison dart frogs, if they are eating the same diet of mites and ants to produce these toxins why have different toxins evolved?


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## Lance (Sep 8, 2008)

I would think it would all depend on the toxins of the plants in each geographical area. Bug eat plants, frogs eats bugs, toxins for frogs. Or is there more then meets the eye here?


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## Ed (Sep 19, 2004)

There are variations depending on the adaptations of the frogs to uptake and sequester the alkaloids. At one time, it was believed that plants had to be the origin of the actual alkaloids but this no longer appears to be true (see Melyrid beetles (Choresine): A putative source for the batrachotoxin alkaloids found in poison-dart frogs and toxic passerine birds ? PNAS) 

The absorption also depends on the modifications the frogs have made to thier own ability to deal with the alkaloids... 

The main sources of the alkaloids for the frogs are inverts include(but are probably not limited to..) beetles, mites, ants, and millipedes 
for a decent review a few years old see http://www.pharmanet.oi.com.br/pdf/np970460e.pdf

Ed


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## MonarchzMan (Oct 23, 2006)

I believe each genus metabolizes the toxins that they secrete. It's just that the components that go into those toxins come from the arthopod items that they eat.


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## Ed (Sep 19, 2004)

MonarchzMan said:


> I believe each genus metabolizes the toxins that they secrete. It's just that the components that go into those toxins come from the arthopod items that they eat.


If I am reading this correctly, you are saying that the frogs manufacture the toxins from precursors ingested in the inverts. I don't think this is the case in the vast majority of dendrobatids. 

Ed


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## MonarchzMan (Oct 23, 2006)

Ed said:


> If I am reading this correctly, you are saying that the frogs manufacture the toxins from precursors ingested in the inverts. I don't think this is the case in the vast majority of dendrobatids.
> 
> Ed


Well, sorta. I was under the impression that the final chemical structure of toxins found in frogs is not the same as found in their arthropod prey?


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## dom (Sep 23, 2007)

Ed said:


> There are variations depending on the adaptations of the frogs to uptake and sequester the alkaloids. At one time, it was believed that plants had to be the origin of the actual alkaloids but this no longer appears to be true (see Melyrid beetles (Choresine): A putative source for the batrachotoxin alkaloids found in poison-dart frogs and toxic passerine birds ? PNAS)
> 
> The absorption also depends on the modifications the frogs have made to thier own ability to deal with the alkaloids...
> 
> ...



The first article you post the one on Melyrid beetles, i read through and it says

"Instead, steroids and triterpenoids in beetles are presumed to originate from plant phytosterols (cho- lesterol, stigmasterol, sitosterol, ergosterol, etc.), which are modified by the beetle or possibly by a symbiont or collection of symbionts (19). The possible role of symbionts in the production of beetle BTXs is being investigated."

so they would not get the toxins straight from plant matter but they do make it from the plant matter that they eat? 



I did some searching and i have alot of articles to read, if anyone is interested i can post them


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## dom (Sep 23, 2007)

In this article it states that the main source for the different range of pumiliotoxins is from the variety of mites they eat, as well as the formacine (sp) ants

Oribatid mites as a major dietary source for alkaloids in poison frogs ? PNAS


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## Ed (Sep 19, 2004)

MonarchzMan said:


> Well, sorta. I was under the impression that the final chemical structure of toxins found in frogs is not the same as found in their arthropod prey?


As far as I know and I could be misremembering, this is not the case for the vast majority of alkaloids used by the frogs. There are some exceptions in three Dendrobates where modification to a specific enantiomer occurs but even in this case the overall backbone and structure of the alkaloid is already in place. 

Ed


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## Ed (Sep 19, 2004)

dom said:


> The first article you post the one on Melyrid beetles, i read through and it says
> 
> "Instead, steroids and triterpenoids in beetles are presumed to originate from plant phytosterols (cho- lesterol, stigmasterol, sitosterol, ergosterol, etc.), which are modified by the beetle or possibly by a symbiont or collection of symbionts (19). The possible role of symbionts in the production of beetle BTXs is being investigated."
> 
> ...


At the moment, if I remember correctly, none of the exact alkaloids have been found in plants (but I haven't really reviewed the literature in a quite awhile so I could be off on this one) so it appears that the invertebrates are either manufacturing it out of basic precursors like some forms of sterols or are modifying existing alkaloids found in plants. 

Ed


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