Frozen Evolution. Or, that’s not the way it is, Mr. Darwin. A Farewell to Selfish Gene.

Organisms adjust of the frequency of mutations through a number of mechanisms, mostly connected with the intensity of repair processes, some of which are even capable of effectively reacting to changes in the environment (Echols & Goodman 1991).For example, if a population of bacteria finds itself in a stressing situation and is in danger of extinction, for example after transfer to an environment with an abnormal temperature, the bacteria undergo an SOS reaction. The individual bacteria begin to mutate faster, increasing the probability that a mutant that will be resistant to this stress factor will occur in the population (Taddei et al. 1997).It happens very frequently that turning off the process of repair of unpaired bases (the mismatch repair system) contributes to increasing the frequency of mutations.Turning off this process in bacteria increases the probability of interspecies recombination by more than an order of magnitude (Velkov 2002)

            Similar processes are apparently active in single-cell eukaryotes.Another mechanism is active in a number of organisms, including multicellular animals and plants, that enables them to accelerate evolution when they find themselves in unfavourable circumstances.In some cases, heat shock proteins (Hsp) are of key importance; this is apparently primarily HSP90 in metazoa (Rutherford & Lindquist 1998; Rutherford 2000; Rutherford 2003). Heat shock proteins allow folding of newly synthesized (linear) proteins into the correct spatial shape and can also “repair” proteins, whose shape was damaged by external effects, such as a thermal shock.The activity of some Hsp is of key importance, especially for proteins, whose primary structure is already affected by the mutations present.Under normal circumstances, Hsp are apparently capable of neutralizing the effect of a substantial percentage of these mutations and are able to ensure that a great many abnormal proteins form a normal and completely functional tertiary structure – a three-dimensional shape.If the organism finds itself under abnormal conditions, the Hsp are mobilized for other functions and there begins to be an acute lack of them in the cell.In this case, the presence of the already present mutations begins to be manifested in the tertiary structure of the proteins and subsequently in the phenotype of the organisms.Thus, under abnormally unfavourable conditions, so far unrevealed genetic variability begins to be manifested in the phenotype of the individual organisms in the population and this variability can become material for natural selection and thus also for adaptive evolutionary changes.Populations and species can thus react rapidly to drastic changes in their environments.