Date: Sun, 1 Nov 1998 12:31:42 From: SCHLAUER@chemie.uni-wuerzburg.de To: cp@opus.hpl.hp.com Message-Id: <aabcdefg3466$foo@default> Subject: Re: sub carnivores
Dear Charles,
> Anyone who feels beleaguered by all this sub-CP business, do not
> worry: you don't have to accept Jan's definition of plant carnivory
> if you don't want to. I don't and the fact that some CP species
> don't produce their own digestive enzymes doesn't trouble me at
> all! :-)
Would you please be so kind to explain to me and the others on this
list what kind of definition for CPs you recommend so that the known
CPs are included but not *all* plants with sticky leaves, cisterns,
etc.
Including too many elements in a class is at least as detrimental to
the concept as including too few. Admitting that we are discussing
points or areas on a gray scale does not mean that there are no
differences. The great advantage of the (oversimplifying) endogenous-
enzyme criterion is the identification of a core group that is pretty
on the black side of the scale.
I think even you or your fellow ecologists will admit that the
bromeliads, _Roridula_, or even _Byblis_ are somewhat less
consistently carnivorous than an "ordinary" CP like _Drosera
rotundifolia_, irrespective of the amounts of prey trapped.
In a case like carnivory in plants, it is certainly not appropriate to
operate with strict definitions and delimited classes. However, in
finite and defined systems (disatvantageous features of current
computer technology) like a CP database, at some point it must be
decided what should be included and what should not. This may of
course be different in a free text where you do not need to consider
formatting criteria like searchability and homogeneity of the data.
Judging by a simple definition or criterion may cut off some of the
information available, but it facilitates both sorting and
understanding why something has been sorted in a certain way. If you
are looking for the light gray shades of carnivory, you must use
textbooks on general Botany or other web pages, not the CP database.
You do not expect irises to be included in an orchid database, do you?
> However, I do have one complaint about your approach to this
> argument, Jan: the fact that other, equally legitimate views exist
> is never acknowledged by you in this list or on the CP database.
> With particular reference to the database, the implication behind
> this is that your views are not disputed, whereas in reality they
> are. This is misleading to readers who are unaware of all the
> differing opinions in this field. A simple qualifying remark here
> or there could remedy this,
This is not quite true. First, there is an introductory text
explaining roughly what is regarded a CP and what is not in the
database. Second, some species frequently mentioned in CP texts but
considered sub-carnivorous for some reason are nevertheless listed in
the database, and explicitly marked as "sub-carnivorous" or "non-
carnivorous" in the "C:" (comment) field, sometimes with a short
explanation. If this remark is not sufficiently qualifying for you,
please explain what you would like to change. I am willing to try to
improve the database wherever possible.
I just do not want to (and I doubt anyone ever will) add *all*
bromeliads or *all* plants with sticky parts, because this would
turn the database into a big mass of noise with only trace amounts of
signal remaining (adding the bromeliads alone would inflate the
database more than fourfold, with absolutely no gain in significant
information).
Apart from the fact that I would no longer be able to maintain and
update the resulting monster appropriately, with any added data of
low relevance, the need to add further data with even less relevance
would grow. If you want to catch even traces ow gray, you must
include the whole scale with the only exception of pure white. But
all who have dealt with similar problems know that the purely white
area is as infinitesimally small as the purely black one. Finally,
the whole plant kingdom would have to be included in a perfect CP
database because there are virtually no plants that do not show any
symptom of the carnivorous syndrome.
Please remember that the database is essentially taxon-based. It is
not intended to be a comprehensive treatise on CP ecology, which would
hardly be possible to implement on the web, even if it was possible
to write such a thing at all.
Kind regards
Jan
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