Le Thu, 26 Jul 2007 12:00:20 +0200, dans fr.sci.biologie,
first_name@last_name.net (Florian) a écrit :

Une bonne revue parue dans PNAS sur le vrai moteur de l'évolution:

The new mutation theory of phenotypic evolution

Recent studies of developmental biology have shown that the genes
controlling phenotypic characters expressed in the early stage of
development are highly conserved and that recent evolutionary changes
have occurred primarily in the characters expressed in later stages of
development. Even the genes controlling the latter characters are
generally conserved, but there is a large component of neutral or nearly
neutral genetic variation within and between closely related species.
Phenotypic evolution occurs primarily by mutation of genes that interact
with one another in the developmental process. The enormous amount of
phenotypic diversity among different phyla or classes of organisms is a
product of accumulation of novel mutations and their conservation that
have facilitated adaptation to different environments. Novel mutations
may be incorporated into the genome by natural selection (elimination of
preexisting genotypes) or by random processes such as genetic and
genomic drift. However, once the mutations are incorporated into the
genome, they may generate developmental constraints that will affect the
future direction of phenotypic evolution. It appears that the driving
force of phenotypic evolution is mutation, and natural selection is of
secondary importance.


http://www.pnas.org/cgi/content/full/104/30/12235

L'usage du français comme langue de communication est impératif. Les
messages pourront cependant comporter des citations courtes dans une
autre langue, sous réserve qu'elles soient traduites en français.

--
DC
Débuts dans les groupes -> <news:fr.bienvenue>
Pour en savoir plus -> <url:http://www.usenet-fr.net>
Rédiger agréablement -> <url:http://www.usenet-fr.net/fur/usenet/repondre-sur-usenet.html>