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From: jespah@milton.u.washington.edu (Kathleen Hunt)
Newsgroups: sci.bio
Subject: Re: Paranormal phenomena and evolution
Message-ID: <15424@milton.u.washington.edu>
Date: 29 Jan 91 23:53:38 GMT
Organization: University of Washington, Seattle
Lines: 115

From: sss3@ukc.ac.uk (S.S.Sturrock)
*>(me, KH)
*>Sorry, evolution *must* include genetic change.  This is the biological
*>definition.  You can discuss environmentally-caused variation if you like,
*>but please don't call it "evolution" or we will all get confused.  
*
*The Biological definition may be incorrect.

I am really puzzled by what you mean by this.  Evolution is primarily a 
biological theory.  The biological definition *is* the definition of evolution.
Perhaps more to the point, the biological definition makes sense --
environmentally-caused variation cannot be passed on to one's offspring,
and thus cannot result in a permanent change in the population.

*I find it highly amusing that Cladistics could be considered as being alive
*and kicking.  Maybe I am wrong but it relies on shared features to define
*a similarity between species ie wings, therefore birds are closely related
*to insects, and bats?!!? :-)
*
*Maybe you can give me a little fresh data.

I believe you are confusing cladistics with pheneticism.  Cladists attempt
to built a classification based *only* on evolutionary relationships.  
Cladists love monophyletic groups, and an "animals with wings" group such
as you describe would drive cladists into a screaming rage.

Pheneticism was the "previous revolution" in systematics -- it was the hot
controversy in the 60's, before cladistics came along.  Pheneticists tried to 
construct classification schemes from a purely operational point of view.   
They group organisms solely on the basis of similarity, not by evolutionary 
history.  The "animals with wings" group is a crude example of the kind
of thing pheneticists have in mind, but their methods are more sophisticated
than that -- they would be sure to notice that bats are similar in many ways
to mammals, and that birds share similarities with dinosaurs.  I believe
the pheneticists' point was that they wanted to construct a classification 
*independent* of evolution, so that they can then look at their 
classification scheme and use it as evidence for or against certain 
theories of evolution.

Of course, pheneticists don't always call themselves pheneticists, and
cladists are often now called "phylogenetic systematists", so the terminology
can get confusing.  Just so you know who I'm talking about, the cladists
would include such people as Hennig, Platnick, Nelson, Wiley, and Cracraft,
and the pheneticists are people like Sokal, Sneath, and Rolff.  Finally,
there is the older group of systematists, the "evolutionary systematists".
That's people like Mayr and Simpson, who use evolutionary relationships
to construct classifications, but also allow morphologically different
groups to be split off from a monophyletic group (like the birds being
given their own class, instead of staying with the dinosaurs).

To put in some historical perspective, the evolutionary systematists are
the older group, and their classification schemes are the ones most of
us are familiar with.  Then the pheneticists (classification by similarity)
came along in the 1960's and fought with the evol. syst. people.  Then,
the cladists (classification by evolutionary relationships) came along
 in the 1970's and fought a series of incredibly
nasty arguments with everyone else -- what one of my professors calls
"the most violent exchanges in biology and maybe in all of science."
(Flame wars, basically.)

The dust has sort of settled now, and from what I gather, cladistics
(now called "phylogenetic systematism", remember) has ended up on top.
However, the evolutionary systematists are still around, and though
the pheneticists have sort of faded, their careful, rigorous methodology
provided tools that everyone uses now.

Well.  I really don't know much about this field -- everything I just 
said is stuff I am basically repeating from systematics seminars I've
been to.  If there is a real live systematist out there on the net, 
please jump in and correct any mistakes I've made!
 
*For timescales take a look at the PHYLUM Trilobitomorpha.  Species in this
*phylum evolved rapidly, very rapidly in fact, and the strata that the fossils
*are preserved in can often be resolved down to seasons!  Tell me that isn't
*a fine enough resolution. :-)

That's an excellent resolution!  Glad to hear it.  Do you have any references
for where I can find out more about this?  Is this common, or is such 
resolution only found in certain rare strata?  What sort of level of 
resolution is there, for example, for the horse fossils?

*Anyway, there are regular instances when an organism has evolved suddenly,
*again, how about the Ammonoidea?  I am quite clear about timescales involved,
*what about the horse, there are NO inbetween fossils, just individual,
*identifiable species.  This is the crux of the matter, it is simple to argue
*that they have stopped evolving, but to then say that 'overnight' they changed
*to a new species and left no record?  No I am not a creationist, or a Christian
*or any other religion.
*
*I would like you insights, or any others for that matter.

I think one big point here is that when an organism appears in the fossil
record suddenly, it does not follow that it evolved suddenly.  Speciation
appears to take place most often among small, isolated populations, and such
a new species may then re-invade the home of its ancestral "mother" species,
prove itself to be fitter, and outcompete the "mother" species.  Throughout
most of the range of the mother species, the fossil record would record a very
abrupt transition -- the "mother" species would be very abundant, and then
the "daughter" species would appear all of a sudden, apparently out of 
nowhere.  The only place that the fossil record would record the
actual evolution of the daughter species is in the small area where the
isolated population was that gave rise to the daughter species.  If you 
want a more complete description of this phenomenon, check out "The
Blind Watchmaker" by Richard Dawkins.

This is not the only way speciation can occur, but it is probably a 
common way (according to current theory, that is...).  The key is that
the actual speciation event tends to take place in a small area.

I am *not* an expert in this field, by the way, and would be happy to hear
other people's opinions on this subjects.  (I am primarily an organismal
biologist -- endocrinology, behavior, all that stuff.)

Kathleen
jespah@milton.u.washington.edu