Time to update taxonomy? - A thought experiment.

Richard Pyle deepreef at BISHOPMUSEUM.ORG
Sat Feb 1 14:21:32 CST 2003

> Do you think the last sentence of our thought experiment is reasonable?
>   What assumptions do we make here?

This is sort of what I was getting at on my second concluding speculation in
the post I just made:  Will we see an unambiguous and clear pedigree for all
living *organisms*; or rather, will we instead see more or less clear
pedigrees of individual *genes* (which may or may not precisely coincide
with the genealogy of the organismal machines that perpetuate them)?  The
latter, I think most would agree.  But the REAL question -- which as far as
I can tell remains unresolved -- is to what extent the two will differ from
each other -- if at all.

> We also assume that we can define what a species is which we
> can't - ask an under graduate student to write and essay on it if you
> have any doubts. No amount of DNA is going to help us sort that one out
> although we may be able to make up some arbitrary rules that only offend
> half the taxonomists.

That's sort of what I was leading to on my first concluding speculation --
the presence or absence of some sort of inflection point in genetic
divergence (whether in certain known critical genes, or amalgamated over the
entire genome) that represents a signpost for when "speciation" happens "for
real".  This relates back to a post I made last July about whether holes in
the "mesh" of organismal genealogy re-close, or form the apex of a more or
less complete and perpetuating split
347). The problem, of course, is that when you get to the splintery ends,
only future events will determine whether the holes re-close, or serve as
the apex for a more or less permanent division in direct reproductive
genetic exchange.

> Our thought experiment has shown that in looking to DNA to solve the
> major problems of taxonomy we are seeking technological solutions to
> intellectual problems. No more saying "If we just sequence another gene"
> or "If we could just sequence a few more individuals". Even if we had
> all the data and all the computing power we still wouldn't answer the
> question.

Perhaps not...but with such enormous quantities of genetic data, I reckon
we'd understand a HELL of a lot more about the natural world around us
(remember the ultimate goal) than we have thus far been able to accumulate
over centuries past, by "traditional" means.

> I presume the goal of taxonomy/systematics is to produce a set of units
> arranged into some form of system that we can all agree on that reflects
> something or is useful for something.

I would argue as I did in my previous post that the goal of
taxonomy/systematics is to serve as a *mechanism* for information exchange;
not so much to establish unambiguous sets of organismal units.

> How/Why/What we do is an
> intellectual question not a technological one. You can throw as much
> data at it as you like you won't find and answer. You have to think
> about it.

I agree that it's an intellectual question -- but more in the sense of
establishing convention, than discovering universal truth.

> The answer you would get if you sequenced everything and gave it to an
> infinitely powerful computer is, of course, 42. Trouble is we are too
> lazy to work out what the question really is.

WOW!  That is *exactly* the point I was trying to make in the concluding
sentence of my penultimate paragraph!  Except that your reference to Douglas
Adams was much more effective than my obtuse diatribe!

Two emails that crossed each other in etherspace.....


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