jcclark at CSUPOMONA.EDU
Sun Sep 6 07:08:30 CDT 1998
At 05:25 AM 9/6/98 -0700, JOSEPH E. LAFERRIERE wrote:
> I am a botanist and have worked in several large herbaria. Some
>of them are still organized on the Engler classification system.
>I know of no botanist today who thinks Engler was correct about
>everything. But it works.
It works for botanists because they are used to it. The herbarium at Rancho
Santa Ana Botanic Garden is arranged alphabetically--that works, too. But
an environmental consultant looking at specimens will never (I hope) get
the idea that the Brassicaceae are more closely related to the Boraginaceae
that they are to the Capparaceae simply because they are closer together in
the RSA herbarium. The systems of Engler and Prantl or Cronquist, both
designed to show evolutionary relationship, are much more likely to confuse
non-specialists, especially Cronquist's system, which is much more recent
and still has its champions.
> Curtis: No, species in nature are not grouped hierarchically.
>What systematists look for is evidence of similar traits in
>different species bases on common ancestry. How we group them in
>families, orders, genera, etc., is a human decision. Cats and lions
>have similarities because they have common ancestry. Therefore
>we humans decide they are in the same family. However, neither the
>cat nor the lion will recognize this, nor any other species
>except Homo sapiens. If a cat and a lion see each other, they do not
>think "Ooh, a relative! Hey, cousin! How's Aunt Tiger?" No. The cat
>will think "Eeeek!!!" while the lion will think "Food!" and no more.
So let me get this straight. The chemical elements in nature are not
grouped periodically, because if a sodium and a potassium should meet, they
won't think "hey, we're in the same column", but rather "I can't relate to
your orbitals." So the periodic table is for our convenience (I'll accept
that), and it otherwise conveys no information, and any other arrangement
would be as useful (I reject that).
>And the decision or what to call a family and what to call an order
>is a human decision.
I'm not talking about what to call it (obviously) or even its
circumscription. I'm talking about the rationale for making it in the first
place. Are we recognizing order, or just making it up?
>Moving back to plants, everyone agrees
>that the composites are derived from a common ancestor. No disagreement
>there. Some of the descendants of that common common ancestor
>themselves became patriarchs of their own lineages (e.g. thistles).
>But does this group of composites represent one family with 12
>tribes or one order with 12 families? That is a strictly human decision.
It is also a human decision to recognize two separate subfamilies,
Tubuliflorae and Liguliflorae, but it is a wrong decision (IMHO), an
unscientific decision, because both turn out to be polyphyletic. It would
make as much sense to group Hypochoeris and Felis because they both have
"cat" as part of their English common names.
>The plants care about this even less than the cat.
If *we*, as systematists, don't care, who will?
Curtis Clark http://www.intranet.csupomona.edu/~jcclark/
Biological Sciences Department Voice: (909) 869-4062
California State Polytechnic University FAX: (909) 869-4078
Pomona CA 91768-4032 USA jcclark at csupomona.edu
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