Download Jean Deutsch

Avant l’« évo-dévo » :
de Bateson à Waddington.
Jean Deutsch
Université P. et M. Curie
Colloque Darwin - Collège de France - 10-12 Juin 2009
Avant l’« évo-dévo » :
de Darwin à Gould.
Jean Deutsch
Université P. et M. Curie
Colloque Darwin - Collège de France - 10-12 Juin 2009
 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
 C.
Darwin (1809-1882)
• Importance des caractères du
développement.
• Le bricolage de l’évolution.
• Le changement de fonction.
Colloque Darwin - Collège de France - 10-12 Juin 2009
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 2009
Fertilization of Orchids, 1862, Chap. VII, p. 348
• Le bricolage de l’évolution.
“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
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
 W. Bateson (1861-1926)
• L’anti-gradualisme
• L’homéose
• La génétique mendélienne
Colloque Darwin - Collège de France - 10-12 Juin 2009
 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
 W. Bateson (1894) Materials for the study of variation
• L’homéose
“ Homeosis:
the essential phenomenon is not
that there is merely a change, but
that something has been changed
into the likeness of something
else”.
Cimex axillaris
Hyménoptère
Colloque Darwin - Collège de France - 10-12 Juin 2009
 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 2009
 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 man’s 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
T.H. Morgan (1866-1945)
• Embryologie et génétique
Colloque Darwin - Collège de France - 10-12 Juin 2009
 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
 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
 R. Goldschmidt (1878-1958)
• Gènes de contrôle
• Le monstre prometteur
• Importance évolutive de
l’homéose
Colloque Darwin - Collège de France - 10-12 Juin 2009
 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
 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 bulldogheads were also monsters.”
Colloque Darwin - Collège de France - 10-12 Juin 2009
 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
 G. de Beer (1899-1972)
• Homologie.
• Hétérochronie.
Colloque Darwin - Collège de France - 10-12 Juin 2009
 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 2009
 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
 C.H. Waddington (1905-1975)
• Paysage épigénétique.
• Canalisation.
• Assimilation génétique.
Colloque Darwin - Collège de France - 10-12 Juin 2009
 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
 C.H. Waddington (1956) Principles of embryology, p. 329
• Developmental pathways and their genetic control
(1) The development of an organ or
complex substance takes place in a
series of steps, each of which is
affected by genes.
(2) 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
 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
 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
 S. J. Gould (1942-2002)
• Les contraintes architecturales du
développement.
• L’importance de l’hétérochronie
de développement.
• L’exaptation.
• La nouvelle synthèse.
Colloque Darwin - Collège de France - 10-12 Juin 2009
 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
 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
 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
 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
 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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Colloque Darwin - Collège de France - 10-12 Juin 2009