RE: [SG,DS, Colonial] Invasive Species

Well the same question could arise for why we had 30 ton carnivores...
Hmmm, because we had 100 ton herbivores....  Because we had 100ft
ferns... Because bigger ferns got more light...

Most things get big because of economies of scale - things like it is 
easier to maintain heat (even to the point of overheating) with a larger
biomass, more area for storage of nutrients and energy, more access
to food (able to reach higher or have more power to crack those tough
hulled nuts).  As Darwin pointed out, if there is a potential niche,
something
will develop to exploit it.  

There doesn't have to be an easy rationalized explanation either - think
of
all those parasitic or symbiotic plants/insects that can only survive
with a
specific partner.  They exist, the results of a long chain of evolution.
There
also exist evolutionary backwaters that deadended but survive today-
i.e.
the coelacanth.  

Particularly vicious lifeforms don't really need justification in an
eco-system.
The examples that you find may the last remnants of a dying breed or
an evolutionary dead end.  Not everything has to "fit" into an ecosystem
-
think appendix.

As for producing defenses before there is an obvious threat -
cross-reaction.
A new report has found that the probable source for the HIV is a
particular breed of chimpanzees found in Africa.  This virus obviously
existed
before contact with man and does nothing to the chimpanzee, but when
introduced to man...

-----Original Message-----
From:	Buji Kern [SMTP:mrbuji@whidbey.net]
Sent:	Wednesday, February 10, 1999 7:00 PM
To:	gzg-l@CSUA.Berkeley.EDU
Subject:	Re: [SG,DS, Colonial] Invasive Species

>In a message dated 99-02-12 01:11:42 EST, you write:
>
><< >very sf, but with a high f component and low s. why would these
killer
> >plants exist before the humans arrive? nature is unlikely to produce
> >defences against a threat which has not yet arrived - this would
> require >>
>What about the Venus Flytrap?	Make it bigger and you can get something
that
>could make a human a mail cource.

>-Stephen

Right, but why would it be bigger? Venus Flytraps eat ants. Maybe the
planet
has _really_ big ants?

-Buji