What is the relationship between plasticity and evolution?

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What is the relationship between plasticity and
evolution?
1. ...does it constrain evolution? 2. ...does it
facilitate evolution?
....and how could you test it?
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The "Baldwin" Effect abilities that initially
require learning are eventually replaced by the
evolution of genetically determined systems that
do not require learning.
does this sound Lamarckian...?
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Baldwin didn't think so....
"This completely disposes of the Lamarkian
factor as far as two lines of evidence for it are
concerned. First, the evidence drawn from
function, " use and disuse," is discredited
since by organic selection," the reappearance, in
subsequent generations, of the variations first
secured in ontogenesis is accounted for without
the inheritance of acquired characters. So also
the evidence drawn from paleontology which cites
progressive variations resting on functional use
and disuse. Second, the evidence drawn from the
facts of " determinate variations " since by
this principle we have the preservation of such
variations in phylogeny without the inheritance
of acquired characters."
James Mark Baldwin. "A New Factor in Evolution."
American Naturalist 30, (1896) 441-451, 536-553
...but others did.
"...contrary to the prevailing belief, Weismann
was a neo-Lamarckist, as Darwin was (1972, p.
v.)...In fact, Weismann's theory as a whole was
not inconsistent with the Baldwin effect
(discussed in Chap. 5). However, what happened
later was that his general statement of
refutation of the inheritance of acquired
characters alone was taken seriously, and it
provided a strong theoretical basis for the
development of neo-Darwinism."
"It has now become clear that neo-Lamarckism has
always been a reasonable theory, and it has stood
the test of time for more than a century. Once
some misunderstandings and inhibitions are
removed, the theory can be regarded as a more
complete theory (than neo-Darwinism) in that it
analyses the evolutionary process in terms of
both the proximate and ultimate mechanisms, and
in that it is especially suited for analyzing the
origin of macroevolutionary change."
Matsuda, Ryuichi (1987) Animal Evolution in
Changing Environments, with Special Reference to
Abnormal Metamorphosis. N.Y. Wiley Press
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Still, how can we account for this phenomenon??
Conrad Waddington in the mid 1900s coined the
term "genetic assimilation" to explain this
phenomenon, and accounted for it this way
Presumably its skin, like that of other animals,
would react directly to external pressure and
rubbing by becoming thicker. This capacity to
react must itself be dependent upon genes. It
may then not be too difficult for a gene mutation
to occur which will modify some other area in the
embryo in such a way that it takes over the
function of external pressure, interacting with
the skin so as to pull the trigger and set off
the development of callosities.
C.H. Waddington. 1942. Canalization of
development and the inheritance of acquired
characteristics Nature 150 563-565.
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great...but is there any evidence for this??
ether application in fruit flies turns this
haltere..... into a wing!! (well, at least a
partial wing)
note this is not a fruit fly...
muextension.missouri.edu
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lab
field
Strathmann, R. R., L. Fenaux, and M. F.
Strathmann. 1992. Heterochronic developmental
plasticity in larval sea urchins and its
implications for the evolution of nonfeeding
larvae. Evolution 46972986.
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Heyland, Andreas, Hodin, Jason. 2004.
Heterochronic developmental shift caused by
thyroid hormone in larval sand dollars and its
implications for phenotypic plasticity and the
evolution of nonfeeding development. Evolution
58 524538.
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Heyland, Andreas, Hodin, Jason. 2004.
Heterochronic developmental shift caused by
thyroid hormone in larval sand dollars and its
implications for phenotypic plasticity and the
evolution of nonfeeding development. Evolution
58 524538.