Re: Paper: A critique of directionality theory


"g" <gillawton@xxxxxxxxxxxxx> wrote in message news:dsjkj2$7q2$1@xxxxxxxxxxxxxxxxxxxxxx

"Robert Karl Stonjek" <rstonjek@xxxxxxxxxxxxxx> wrote in message
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Proceedings: Biological Sciences
ISSN: 0962-8452 (Paper) 1471-2954 (Online)
Issue: Volume 273, Number 1586 / March 07, 2006

Pages: 635 - 639
DOI: 10.1098/rspb.2005.3344

A critique of directionality theory

Michael Bulmer A1
A1 The Old Vicarage Chittlehampton, Umberleigh, Devon EX37 9RQ, UK

Abstract:
Directionality theory suggests that demographic entropy, defined in a way
analogous to thermodynamic entropy, is as important as the Malthusian
parameter in determining life history evolution in an age-structured
population. In particular, it suggests that entropy should increase in
equilibrium species and decrease in opportunistic species. This theory has
been applied to explain the evolution of body size and of senescence. It
has
been claimed recently that this theory has been validated by a simulation
study, but it is argued here that this study reveals substantial flaws in
directionality theory and that the Malthusian parameter rather than
entropy
is the appropriate tool in the study of life history evolution.

What is being compared and analyzed in the article?

ECOLOGICAL CONSTRAINTS can be viewed as filters, whereby selection means
nothing more, nor anything less, than: Some prevail, some squeak by, and
some don't get to stick around long enough to reproduce; and those of the
first two are the parents of any and all successors.

LIFE-HISTORY PROPERTIES ??? [snip long series of surmises as to
what life-history properties might mean.]

Sorry. I just find myself unable to come up with what is the meaning of
"life-history property." Perhaps the author of the article in question used
this term to mean "acquired characteristics." Unfortunately, he leaves us
(or me, at least) hanging as to he might mean insofar as to say that
"life-history properties" relate to ecological constraints and give rise to
a central problem in the understanding of each, or both.
From that nebulous island of confusion, he continues on to "directionality
theory."

DIRECTIONALITY THEORY must mean that [snip more surmises as to
what this must mean]

It should not surprise anyone if I say that if we do not know,
for a certainty, where evolution is supposed to have gone, it is no easy
matter for us to calculate by just what percentage that is has missed the
mark. ...

So, pardon my lack of gullibility if I ask what entropy has to do with that.

Though I hate to repeat myself, ... [snip long repetition]

[Also snip several quotes which seem to be from various papers by Lloyd
Demetrius, not from the paper by Bulmer which is abstracted above.
Resuming with one final quote from Demetrius]

Now on to the conclusion (or conclusion of the critique) and:

"This paper assesses the validity of these predictions by employing a
demographic dataset of 66 species of perennial plants. This empirical
analysis is consistent with directionality theory and provides support for
its significance as an explanatory and predictive model of life-history
evolution."

Sorry, I am unconvinced that there is any tangible meaning of
"directionality" in this context, nor any way to measure any quantitative
entropic margin of deviation therefrom. I do not see that it adds anything
to explaining anything other than the basic homeostasis and spiralar change
over many reproductions, and the interactions of these changes -- favoring
some here, disfavoring others there. Nor do I perceive life history to be
anything more than hindsight.

Gil, your ignorance is forgivable, but your stupidity deserves comment.

The abstract above by Bulmer is loaded with jargon. Some of it is
jargon which is in common use in evolutionary biology - for example
"life-history properties" or "Malthusian parameter". But some of it
is jargon which is much more specialized since it arises from the
theories of Lloyd Demetrius, whom Bulmer is criticizing. These include
"directionality theory" and "demographic entropy".

You are mildly ignorant for not understanding what 'life-history' means
to an evolutionary biologist. But you are incredibly stupid to think that
you can analyze the meaning or lack of meaning of a piece of technical
jargon by just thinking about it. And you show signs of lack of contact
with reality in apparently assuming that this kind of rambling
deconstruction of technical text will resonate with your readership.

I have criticised many of your postings, but frankly, this one
achieved the level of self-parody.



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