Date: Wed, 28 Oct 1998 15:59:18 From: SCHLAUER@chemie.uni-wuerzburg.de To: cp@opus.hpl.hp.com Message-Id: <aabcdefg3430$foo@default> Subject: Re: sub-carnivores
Dear Nick,
Please check out the archives of this list for more discussions on
this trashed-to-death (but still rather interesting) topic.
> Given these observations, wouldn't it be reasonable to consider
> Brocchinia "proto-carnivorous" or something similar.
I would consider _Brocchinia_ as a poor debris collector in some
situations (in cultivation it is frequently a fairly ordinary shaped,
bromeliad rubbish bin), not much more. It is interesting as a
bromeliad (together with hundreds of other bromeliads), not as a cp.
"Proto-" or "pre-carnivorous" are terms that insinuate future
evolutionary events. As we are not really able to *predict*
evolutionary courses, I would not recommend using such terms. "Sub-
carnivorous" is a designation that appropriately describes the status
of the creatures discussed here without any assumptions about future
developments.
> It seems probable that carnivorous pitcher plants evolved from more
> generalized debris traps,
Do you have any evidence for this assumption?
> and intermediate stages probably had a trapping mechanism before
> they evolved digestive enzymes.
Sure? Why? Digestive enzymes are ubiquitous at the intracellular
level, and it is not very difficult to change their compartmental
destination.
> Brocchinia does not appear to be just another typical tank-forming
> bromeliad.
To me it appears to be exactly this.
> I've never been a fan of strict black-and-white categories in biology.
Why not? They can be fun where they exist.
> There are almost always exceptions :-) For example, hasn't it been
> suggested that Nepenthes lowii obtains much of it's nutrients from bird
> droppings? If so, is it still carnivorous? Maybe post-carnivorous?
No reason to worry, it still is a fairly successful (& digesting!)
carnivore.
The only gray shade that really troubles me (well, I am not really
depressed by it, but it definitely bothers me more than any bromeliad)
is the apparent absence of digestive activity in some species of
_Heliamphora_. _Darlingtonia_ should be re-investigated. I am not
sure if former reports on lacking enzymes are trustworthy.
Kind regards
Jan
PS: Please do not interpret this message as a call to throw away your
_Brocchinia_!
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