Две теории биологической эволюции. Гродницкий Д.Л. - 131 стр.

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ronment and in genome. Hence a theory of evolution must be able to explain, how
transition is made from one stable phenotypic state to another. The transition starts
after alteration of environment which in a nonspecific way disturbs coordination
of developmental processes. As a result, stability of normal ontogeny decreases,
and variation of population grows, since the developmental system generates a
considerable number of abnormal phenotypes (morphoses) along with production
of the previous norm. The morphoses are unreliably inherited. However, they pres
ent material for further natural selection. Whenever one of the newly generated
phenotypes appears to be able of living in the changed environment, then selection
leads to its genetic assimilation, restructuring the genome of the population.
Consequently, an initially noninherited morphosis becomes a reliably inherited
new norm acquired by the majority of developing individuals. This approach to evo
lution based on Waddington’s concept of genetic assimilation of morphoses and on
Schmalhausen’s concept of stabilizing selection represents a paradigm which is in
fact alternative to the currently predominating synthetic theory: evolution begins
from phenotypic changes and ends at the germ cell genome rather than the oppo
site, as predicted in the synthetic theory. Mendelian factors are considered here as
relations between alternative ontogenetic trajectories, and hence are products of
evolution rather than raw material for evolutionary change. The proposed paradigm
can be termed «epigenetic theory of evolution».
A major philosophic property of the epigenetic theory is its view of the organisms
as whole entities in which each part behaves to maintain stability of the whole in its
environment. Hence, the whole determines behavior of the parts, e. g. phenotype
determines the organization of its genotype. By contrast, the synthetic theory
assumes that gene characters govern the evolutionary behavior of the organisms.
Thus, evolution is accompanied by genetic changes, but is not restricted to
them. In fact, macro effects of natural selection should be viewed irrespective of
genetic properties of the organisms and are much more strongly dependent on their
enviroment and morphofunctional organization. The approach presented in this book
accepts logics contrary to the neoDarwinian perspective: genome alteration is even
tual, but not the starting point of evolution (Krasilov 1984). Meanwhile, the epige
netic concept allows adequate interpretation of the existing genetic knowledge in
morphologic and developmental terms (Liubarsky 1996). Actually, the epigenetic
theory is no altenative, but a more general concept related to neoDarwinism: accept
ing the epigenetic concept, we will not lose knowledge accumulated to date, but
instead obtain novel perspectives to further develop evolutionary biology.
SUMMARY
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