XII.7.4 Organisms whose individual development is based on epigenetic processes have greater evolutionary potential than organisms whose constitution is purely genetically-determined

Organisms with “hard”, i.e. only genetic programming, of their body structure would apparently have much worse potential for further evolutionary development than organisms in whose ontogenesis epigenetic processes play a more important role (Kirschner & Gerhart 1998).It is hard to imagine the evolution (anagenesis) of an organism that would have special genes for the lengths of nerves, veins, muscles and bones in a certain limb.The limbs of such an organism could change in evolution only if all the participating genes were to mutate simultaneously in a suitable manner.In real organisms, the lengths of the nerves, veins, muscles and bones of the limbs are determined epigenetically so that, when a mutation occurs changing the parameters of any of these components, the other components adapt to this and, during ontogenesis, a functional, although somewhat altered, limb is formed.Participation of epigenetic processes in the regulation of ontogenesis ensures that, even if a random mutation somehow affects the progress of the ontogenetic processes, ontogenesis as a whole will most probably once again lead to the formation of a functional and viable organism.Experience gained in study of developmental malformations, such as two-headed calves, drosophila with legs instead of antennae or with eyes formed on the surface of various organs, six-legged frogs, frogs with eyes inside their mouths instead of on top of their heads, etc., shows that these are not unfounded theoretical considerations(Rollo 1994). Whether the malformations occur as a consequence of genetic mutations or as a result of a nongenetic defect during ontogenesis, at least partly functional organism is usually formed.If there were sufficiently effective reproductive isolation, it would apparently be only a question of suitable selection pressures for the functioning of these monsters to be evolutionarily “tuned” so that they could compete with the original form of the organism in utilizing a suitable niche.

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The classical Darwinian theory of evolution can explain the evolution of adaptive traits only in asexual organisms. The frozen plasticity theory is much more general: It can also explain the origin and evolution of adaptive traits in both asexual and sexual organisms Read more
Draft translation from: Evoluční biologie, 2. vydání (Evolutionary biology, 2nd edition), J. Flegr, Academia Prague 2009. The translation was not done by biologist, therefore any suggestion concerning proper scientific terminology and language usage are highly welcomed. You can send your comments to flegratcesnet [dot] cz. Thank you.