You wrote:
> We court unpopularity by continuing. Are you willing to take the risk ?
Given the now-effective killfile operating vis a vis some potential objectors,
of course.
I take the point on D. crumenatum and other mat formers - mine flowered last
w/end with upward of a thousand blossoms. (No doubt you have a tree full, but
this is Britain.) However, the legendary complexity of the orchid flower in
general implies that this complexity does something, or once did something;
and the only thing that it could have done it to was either le bon dieu or its
pollinator. No?
Anyway, to the tetchy concept of swarms. All sciences go through three
phases: naming the parts, building a phenomenology - what works - and finally
an understanding of the clockwork: why the divisions, why the system in
question works. Plant taxonomy was confronted with the riches of the world in
the C18 and C19th, and reacted with names, sets and other completely
understandable and helpful things. However, we are now moving into the third
of the three stages in biology, and these frankly artificial and usually
conceptual divisions will not quite do. Some things need splitting, some need
lumping. Some "things" are not really things at all, but artifacts of
observation. Practically, anyone who operates in the field knows that the more
you see, the more the neat boundaries tend to blur. Aerides odorata is common
across SE Asia, but a Nepali, Sri Lankan and Sumatran representative of the
local population variance are really very different from each other. If they
were sympatric, no doubt someone would have added two new species - even
genera - to the crowded list of sarcanthineae. Well, of course; for what was
Hooker - or whoever named the (I think Indian) holotype - to know of these
other places at that time. And so forth. But times have changed.
Any population has a variance associated with it. Plot any two characteristics
of a species - petal width, petal length - for several dozen field-measured
representatives and you do not get a point, but a blob. The issue is whether a
related but potentially distinct blob overlaps or is distinct enough to make
it useful to treat its members as distinct. There are three ways into this.
The first, which I find preferable over the others, is for someone who knows
the class of organism well - and these specific populations in particular - to
make a judgement as to whether how they live in the round makes them truly
distinct. Essentially, is it helpful to the expert mind to separate these
entities or no? And by expert, I don't mean someone adept at whisker-counting,
but one possessed of an ecological expertise which asks whether the lives led
by the populations makes them effectively distinct in habit, sexual
transmission and role.
The second is to apply rigor to the phenotypes. This uses principal component
analysis to arrive at a tree structure. Colleagues of mine use this tool on
human populations to see which groups are distinct in their - for example,
political behaviour - with an aim to tailor communications specific to the
subgroups which emerge from this. There is an example where we worked on UN
urban data to arrive at a similar classification of the world's cities on
www.chforum.org/library/xc132.html#dendro This procedure removes - or renders
formal - the human judgement of what matters.
The third procedure uses information from the analysis of the genome and
matters dependent on it. This is pretty primitive at the moment: one or more
genes only, difference measured not for what it says but for how it says it. I
suspect this approach will mature as understanding of the proteome evolves:
that is, what turns off and on in response to which signals in order to
generate a leaf, this kind of leaf, this kind of leaf with hairs...
Ultimately, how you classify something depends on what you want to do with it.
Engines: {IC, turbine, stirling} IC: {sparked, not sparked}; Sparked: {two
stroke, four stroke}; Two stroke: {diddle and dah}. But you could also say
Engines: {durable, high power to weight}; etc or Engines: {pollutive, low
emissions}; and so forth.
There is no universal way of dividing a population into sets, any more than
there is one answer to the question "why?" (Why is that flower red? Because
Mrs Jones chose it and she like red; because red sells best so horticulturists
breed it and florists stock it; because of anthrocyanin; because humming birds
see red; because that is the colour worn by grooms at weddings ...)
But enough.
_____________________________________
Oliver Sparrow
Tel: UK (0)20 7736 9716
www.chforum.org
www.treknepal.org
www.datafreeze.com
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