Mutations, i.e. changes in the structure of genetic material respecting the rules of writing of genetic information, are absolutely essential for biological evolution.In the absence of the formation of new mutations, evolution would sooner or later stop and organisms would stagnate at the achieved stage of development.Species would not be able to react to substantial changes in the external environment and would probably die out.Although it is plausibly assumed that most new mutations are more or less detrimental for their bearers, the formation of new mutations is vitally important from the standpoint of the population or the species.Consequently, it is not possible to consider mutations to be simply errors occurring in the transfer of genetic information as a consequence of imperfections in the relevant molecular biological processes occurring in the cells and the process of mutagenesis to be a side (or even undesirable) product of evolution.As it is possible, for example, to select strains of yeast with reduced frequency of mutations {7045}, it will be closer to reality to consider this to be a complicated and highly adaptive process, the product of long-term biological evolution.

            This chapter will be concerned with the most important types of mutations encountered in modern organisms.We will consider types of mutations classified from the standpoint of their physical nature, mechanism of formation or importance for biological fitness.We will pay special attention to the randomness of mutations and the possible evolutionary importance of environmentally directed mutations.

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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.