Prsentation PowerPoint

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Avant l évo-dévo  de Bateson à Waddington.
Jean Deutsch Université P. et M. Curie
Colloque Darwin - Collège de France - 10-12 Juin
2009
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Avant l évo-dévo  de Darwin à Gould.
Jean Deutsch Université P. et M. Curie
Colloque Darwin - Collège de France - 10-12 Juin
2009
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• C. Darwin 1809-1882
• W. Bateson 1861-1926
• T.H. Morgan 1866-1945
• R. Goldschmidt 1878-1958
• G. de Beer 1899-1972
• C.H. Waddington 1905-1975
• S. J. Gould 1942-2002

Colloque Darwin - Collège de France - 10-12 Juin
2009
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• C. Darwin (1809-1882)

• Importance des caractères du développement.
• Le bricolage de lévolution.
• Le changement de fonction.

Colloque Darwin - Collège de France - 10-12 Juin
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The Origin of Species, 1st edition, Chap. XIII,

• Importance des caractères du développement.

The structure of the embryo is even more
important for classification than that of the
adult. Community in embryonic structure
reveals community of descent.
Colloque Darwin - Collège de France - 10-12 Juin
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Fertilization of Orchids, 1862, Chap. VII, p. 348

• Le bricolage de lévolution.

Although an organ may not have been originally
formed for some special purpose, if it now serves
for this end we are justified in saying that it
is specially contrived for it. On the same
principle, if a man were to make a machine for
some special purpose, but were to use old wheels,
springs, and pulleys, only slightly altered, the
whole machine, with all its parts, might be said
to be specially contrived for that purpose. Thus
throughout nature almost every part of each
living being has probably served, in a slightly
modified condition, for diverse purposes, and has
acted in the living machinery of many ancient and
distinct specific forms.
Colloque Darwin - Collège de France - 10-12 Juin
2009
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The Origin of Species, 1st ed., Chap. VI
Difficulties on Theory, p. 191

• Le changement de fonction.

In considering transitions of organs, it is so
important to bear in mind the probability of
conversion from one function to another.
Colloque Darwin - Collège de France - 10-12 Juin
2009
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• W. Bateson (1861-1926)

• Lanti-gradualisme
• Lhoméose
• La génétique mendélienne

Colloque Darwin - Collège de France - 10-12 Juin
2009
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• W. Bateson (1894) Materials for the study of
  variation

treated with especial regard to DISCONTINUITY in
the Origin of Species
Colloque Darwin - Collège de France - 10-12 Juin
2009
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• W. Bateson (1894) Materials for the study of
  variation

• Lhoméose

Homeosis the essential phenomenon is not that
there is merely a change, but that something has
been changed into the likeness of something else.
Colloque Darwin - Collège de France - 10-12 Juin
2009
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• W. Bateson (1894) Materials for the study of
  variation

• La génétique

The only way in which we may hope to get at the
truth is by the organisation of systematic
experiments in breeding. Sooner or later such
investigation will be undertaken and then we
shall begin to know.
Colloque Darwin - Collège de France - 10-12 Juin
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• W. Bateson, 1900

Problems of Heredity as a Subject for
Horticultural Investigation. Journal of the Royal
Horticultural Society. 25 54-61.

• La génétique

 a remarkable memoir by Gregor Mendel, giving
the results of his experiments in crossing
varieties of Pisum sativum. An exact
determination of the laws of heredity will
probably work more change in mans outlook on the
world, and in his power over nature, than in any
other advance in natural knowledge that can be
foreseen.
Colloque Darwin - Collège de France - 10-12 Juin
2009
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• T.H. Morgan (1866-1945)

• Embryologie et génétique

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• T.H. Morgan (1928) The Theory of the Gene, p.
  316.

illusion that each mutant character is the
effect of only one gene and that each unit
character has a single representative in the germ
material. On the contrary, the study of
embryology shows that every organ of the body is
the end-result, the culmination of a long series
of processes. If very many steps are involved in
the development of a single organ, and if each of
these steps is affected by the action of a host
of genes, there can be no single representative
in the germ-plasm for any organ in the body.
Colloque Darwin - Collège de France - 10-12 Juin
2009
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• T.H. Morgan (1934) Embryology and Genetics, p. 16

The question arises as to how the gene produces
its effect on the protoplasm of the cells, for it
is in the protoplasm that the character is
manifest. 
The answer will have to wait until evidence can
be obtained from experimental investigation. 
Colloque Darwin - Collège de France - 10-12 Juin
2009
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• R. Goldschmidt (1878-1958)

• Gènes de contrôle
• Le monstre prometteur
• Importance évolutive de lhoméose

Colloque Darwin - Collège de France - 10-12 Juin
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• R. Goldschmidt (1938) Physiological Genetics

• Gènes de contrôle (rate genes)

The mutant gene produces its effect, the
difference from the wild-type, by changing the
rates of partial processes of development. These
might be rates of growth or differentiation,
rates of production of stuffs necessary for
differentiation, rates of reaction leading to
definite physical or chemical situations at
definite times of development, rates of those
processes which are responsible for segregating
the embryonic potencies at definite times.
Colloque Darwin - Collège de France - 10-12 Juin
2009
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• R. Goldschmidt (1933)
• Some aspects of evolution. Science. 78, 539-547.

• Le monstre prometteur

the importance of rare but extremely
consequential mutations affecting rates of
decisive embryonic processes which might give
rise to what one might term hopeful monsters,
monsters which would start a new evolutionary
line if fitting into some empty environmental
niche. We must not forget that what appears
to-day as a monster will be to-morrow the origin
of a line of special adaptations. The dachshund
and the bulldog are monsters. But the first
reptiles with rudimentary legs or fish species
with bulldog-heads were also monsters.
Colloque Darwin - Collège de France - 10-12 Juin
2009
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• R. Goldschmidt (1940) The Material Basis of
  Evolution

Homeosis and segmentation, p. 323-338.
We turn now to a group of facts which links
genetics, development and evolution. The
well-known case of the assumption of snake-like
form by saurians through the increase in
vertebral number and rudimentation of the
extremities. A single genetic change affecting
the rate of early embryonic features of
segmentation may, therefore, have produced in a
single mutational step at least the fundamental
elements of the whole group of adaptations to
crawling movement.
Colloque Darwin - Collège de France - 10-12 Juin
2009
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• G. de Beer (1899-1972)

• Homologie.
• Hétérochronie.

Colloque Darwin - Collège de France - 10-12 Juin
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• G. de Beer (1938) Embryology and Evolution, p.
  66

• Homologie.

It is clear that characters controlled by
identical genes are not necessarily homologous.
It is clear that homologous characters need
not to be controlled by identical genes.
The homology of phenotypes does not imply the
homology of genotypes. The analysis of the
concept of homology in terms of single genes
therefore breaks down.
Colloque Darwin - Collège de France - 10-12 Juin
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• G. de Beer (1940) Embryos and Ancestors, p. 34

• Hétérochronie.

The strength of the internal factors of
development can vary and exert their effects at
different rates, with the result that the time of
appearance of a structure can be altered. To
this shifting along the time-scale the term of
heterochrony is applied. It is thus possible for
two organs to reverse their appearance in
successive ontogenies, and, by varying the rates
at which animals become mature, adult structures
can be reduced to a vestige and discarded, or
youthful structures can become adult.
Colloque Darwin - Collège de France - 10-12 Juin
2009
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• C.H. Waddington (1905-1975)

• Paysage épigénétique.
• Canalisation.
• Assimilation génétique.

Colloque Darwin - Collège de France - 10-12 Juin
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• C.H. Waddington (1940) Organisers and genes

• Epigenetic landscape

The symbolic representation of developmental
processes can be spoken as epigenetic
landscape.
Epigenesis. The development of the organism by
the new appearance of structures and functions,
as against the unfolding or growth of entities
already present in the egg at the beginning of
development (Preformation). (J. Needham)
Colloque Darwin - Collège de France - 10-12 Juin
2009
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• C.H. Waddington (1956) Principles of embryology,
  p. 329

• Developmental pathways and their genetic control

• The development of an organ or complex substance
  takes place in a series of steps, each of which
  is affected by genes.
• At each step there are several genes acting, and
  the actual development which occurs is the
  resultant of the balance between the opposing
  gene-instigated tendencies.

Colloque Darwin - Collège de France - 10-12 Juin
2009
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• C.H. Waddington (1942) Canalization of
  development and the inheritance of acquired
  characters. Nature, 150 563-565

Developmental reactions, as they occur in
organisms submitted to natural selection, are in
general canalized. That is to say, they are
adjusted so as to bring about one definite
end-result regardless of minor variations in
conditions during the course of the reaction.
The evidence for this comes from two sides, the
embryological and the genetical. The
canalization, or perhaps it would be better to
call it the buffering, of the genotype is
evidenced most clearly by constancy of the wild
type.
Colloque Darwin - Collège de France - 10-12 Juin
2009
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• C.H. Waddington (1953) Genetic assimilation of
  an acquired character. Evolution, 7 118-126.
• (1956) Genetic assimilation of the Bithorax
  phenotype. Evolution, 10 1-13.

Genetic assimilation is a name which has been
proposed for a process by which characters which
were originally acquired characters in the
conventional sense, may become converted, by
process of selection acting for several or many
generations on the population concerned into
inherited characters. Genetic assimilation
is brought about by the operation of orthodox
genetic and embryological principles.
Colloque Darwin - Collège de France - 10-12 Juin
2009
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• S. J. Gould (1942-2002)

• Les contraintes architecturales du
  développement.
• Limportance de lhétérochronie de
  développement.
• Lexaptation.
• La nouvelle synthèse.

Colloque Darwin - Collège de France - 10-12 Juin
2009
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• S. J. Gould R.C. Lewontin (1979) The spandrels
  of San Marco and the Panglossian paradigm a
  critic of the adaptationist program. Proc. Roy.
  Soc. Lond. B, 205 581-598.

Constraints restrict possible paths and modes of
change so strongly that the constraints
themselves become much the most interesting
aspect of evolution.
Colloque Darwin - Collège de France - 10-12 Juin
2009
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• S. J. Gould R.C. Lewontin (1979) The spandrels
  of San Marco and the Panglossian paradigm a
  critic of the adaptationist program. Proc. Roy.
  Soc. Lond. B, 205 581-598.

Colloque Darwin - Collège de France - 10-12 Juin
2009
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• S. J. Gould (1977) Ontogeny and Phylogeny, p.
  246-7.

A clock model of heterochrony We want to plot
size and shape as two potentially independent
vectors operating during the life time of an
organism. To do this, we set up a semicircular
clock with two hands. One hand represents our
best statistic for a measure of size. The
other hand measures shape, which may be
disconnected from its ancestral relationship to
size during evolution. The clock has three
scales corresponding to size, shape and
developmental age.
Colloque Darwin - Collège de France - 10-12 Juin
2009
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• S. J. Gould E.S. Vrba (1982) Exaptation, a
  missing term in the science of form.
  Paleobiology, 8 4-15.

We suggest that characters, evolved for other
usages (or for no function at all) and later
co-opted for their current role, be called
exaptations.
Colloque Darwin - Collège de France - 10-12 Juin
2009
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• S. J. Gould (1977) Ontogeny and Phylogeny, p.
  408.

• La nouvelle synthèse.

the evolutionary significance of changes in
gene regulation. An understanding of regulation
must lie at the center of any rapprochement
between molecular and evolutionary biology for
a synthesis of the two biologies will surely take
place, if it occurs at all, on the common field
of development.
Colloque Darwin - Collège de France - 10-12 Juin
2009
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Je vous remercie de votre attention. jean.deuts
ch_at_snv.jussieu.fr
Colloque Darwin - Collège de France - 10-12 Juin
2009