> On 15/09/2011 03:38 AM, Patrick Elliott wrote:
>> On 9/14/2011 6:24 AM, Invisible wrote:
>>> Are fungi poisonous on purpose, or is it just a side-effect of their
>>> unusual body chemistry?
>>
>> Nothing is "poisonous on purpose", everything is a side-effect of
>> different body chemistry. It just happens that, in some cases, those
>> side effects make them a lot bloody harder for other things to eat.
>
> OK, but consider this: The venom of the Black Widow spider is "designed"
> to be lethal to insects - and indeed it is. To mammals, it's harmless.
> It has no effect on dogs, cats, mice... oh, but by freak coincidence, it
> happens to be deadly to humans. How unlikely is that?

The production of that venom is beneficial to the spider as it make it 
easier for it to get it's food. So, it's a survival advantage.

>
> Point being, humans aren't the target. It just happens to work on them.
> Insects are the target.
>
>> In
>> the case of Fungi, however, it may also lend itself to death near the
>> fungi, and this more nutrients, or it might have a similar effect on
>> other fungi, which are in competition, and just, by coincidence, happen
>> to effect humans, and animals. Most often, the effected species are
>> insects. Thus, anything that, for example, has a nervous system, is
>> likely to have the unfortunate coincidence of also being harmed by
>> something that originally only was lethal to insects.
>
> You're aware that insects have an utterly different nervous system to
> mammals, right?
>
> For example, permethrin is a lethal fast-acting nerve toxin... to
> insects. To mammals it's almost completely harmless. (Except cats,
> randomly.)
>
>> As Darwin said, "No adaptation is ever for the explicit benefit, or
>> harm, of another species. It can only benefit the species that has it,
>> any effect it has on other species is happenstance."
>
> Well, yes, to a degree that's true. It's also clear that, for example,
> snake venom is "obviously" designed to kill the things that snakes eat.
> I'm just wondering whether fungi deliberately manufacture substances for
> no other reason than to prevent them being eaten, or whether the stuff
> that makes them so poisonous is just a normal part of their internal
> chemistry.

Here also, it makes it much easier for the snake to capture it's food. A 
quick bite and let go. Leisurely follow the poisoned prey untill it dies 
= easy meal.
It also a defencive side effect: A predator comes up, a quick bite and 
that predator is no longer a treat, even if it survive the poison. The 
pain and sickness will teach it no to try again, protecting other snakes 
in the future.

As for the poisonous fungi, the toxine is prety usefull to cull down 
competition = more room for it's devlopment, and fend off nasties bent 
on eating the fungi, increased survival chances.

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