J.E. Shields
Tue, 23 Dec 2003 12:03:40 PST
Jamie, John, Mark, and all,

First, a very Merry Christmas to you all!

I can feel sympathy for John and Mark.  On the other hand, I am a 

I first read Charles Darwin's "Origin of Species" when I was in high school 
(only a couple years after John finished high school, I suspect).  I was 
mentally prepared for it when I started to read it, and it made deep and 
lasting impression in my thinking.  As we now realize, evolution isn't a 
hypothesis, it is the theoretical foundation of our understanding of all 
modern biology.  Without it, biology would not be a coherent science.

At the heart of it all is the genetic system of living 
organisms.  Evolutionary descent is all about changes in genetics.  Those 
"genetics" are in fact the copying, transmission, and changes in DNA, and 
their subsequent expression in the living organisms.  The modern molecular 
geneticist has mathematical tools to help him or her estimate the 
relatedness of the DNAs of whole groups of organisms.  The overt physical 
structures of organisms are handy tools for identifying them to Genus, 
species, and subspecies.  But they are rough approximations.   The DNAs are 
in fact the written records of the relationships between organisms.

Structural or anatomical schemes for classifying organisms were a great 
start for biology, but they go clear back to Carl Linnaeus in the 18th 
century.  So while we may lament the fading of some of the old, familiar, 
tools of our trade in horticulture and botany, the  brave new world of 
molecular genetics is in the long run going to be the story -- the truer 
story -- of life on our planet.   I think the old structural keys to 
identification will still be useful, but as Jamie said, we will need 
cross-references to connect them to the new, molecular classifications and 

In the new, cladistic approach to classification, there are ambiguities, 
just as there were in the old.  Whether Scilla should be split into two or 
into twenty other genera is always going to be somewhat a matter of 
opinion, rather than fact.  The facts never have and still do not fall 
neatly into categories of Family, Genus, and species.

What is important, and the revisions that will persist in the long run, are 
those that remove less-related groups from our older genera.  Moving some 
Scilla to Muscari would imply that Scilla as it used to be was not made up 
of plant species all of which were more closely related genetically to each 
other than any of them was to any species outside Scilla.

Alan Meerow has seen the same things with the Rain Lilies, where our older 
existing groups of Zephyranthes and Habranthus do not obey the rule of 
nearest relatives.  There are apparently three groups, not two, and their 
members are scattered between both thiese traditional genera.  Length of 
the stamens turns out to be a superficial trait, not a fundamental one.

I see a bright future in the next few decades for those writers who can 
rationally and clearly connect the  conclusions of the new biology to the 
traditional approach.  Your next book, John?

Best to all,
Jim Shields
hardcore biochemist

At 07:49 PM 12/23/2003 +0100, Jamie wrote:
>I feel for ya, but I can't reach back that far...any more.  We are on
>another wave of understanding and, as you mentioned, it does mean the
>destruction of our know systems of classification.  I do believe that we
>will find we have missed a few items on our discovery trip through DNA
>analysis.  The end of the puzzle is no where in sight, even if some would
>like to let us think this.

Jim Shields             USDA Zone 5             Shields Gardens, Ltd.
P.O. Box 92              WWW:
Westfield, Indiana 46074, USA
Tel. ++1-317-867-3344     or      toll-free 1-866-449-3344 in USA

More information about the pbs mailing list