III.13 The possibility of environmentally directed mutations alone would still not suffice for Lamarckian evolution.

The existence of mechanisms that cause or rather make more probable the occurrence of mutations enabling organisms to react adequately to a change in the external conditions is occasionally interpreted as documentation of the functioning of Lamarckian evolution and as throwing doubt on Darwinistic evolution.However, these ideas are incorrect.As was already emphasized, the individual mechanisms of generating useful mutations are related only to specific mutations in specific organisms in specific situations.The vast majority of mutations occur at random and even the molecular apparatus enabling the generation of environmentally directed mutations arose as a consequence of random mutations, i.e. Darwinistic evolution.It should be emphasized that, even if it were possible to generate  just those mutations during evolution that would enable an organism to effectively overcome the unfavourable effect of the environment or, on the other hand, to utilize new resources in the environment, Lamarckian evolution could still not become an important factor in the development of organisms.There are at least three fundamental obstacles that stand in the way of its effective functioning.

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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.