Mutation evolutionary strategies

In evolutionary strategies, a parent string produces X offspring the fittest of the 1 + X individuals is selected to be the single parent for the next generation of offspring. There is no crossover operator in evolutionary strategies, only mutation. 

An alternative approach for computational evolution, termed the Evolutionary Strategy (ES) was developed independently by Rechenberg and co-workers. The ES employs many of the same ideas as the GA, including mutation and selection. However, the ES always uses real-valued encoding. A particular evolution strategy is usually denoted as a i -I- k -ES. The parameter p refers to the constant population size, whereas the parameter X refers to the size of the pool out of which a new population is selected. Obviously, X must be at least as large as p. 

Figure Id presents some landscapes of 2D optimization problems. There is no doubt that gradient approaches will be superior in the case of isolated hills however when applied to multihill problems they fail to find the global optimum. Evolutionary strategies are able to detect the absolute maximum at the prize of a large mutation radius and many trials during many generations.

The evolutionary strategies described above either wait for mutations to occur naturally or use a mutagen to generate mutations. In an approach described by... 

Naturally, the first step of each evolutionary project is the creation of diversity. The most straightforward approach to create a library of proteins is to introduce random mutations into the gene of interest by techniques such as error-prone PCR or saturation mutagenesis. The success of random mutagenesis strategies is witnessed by their ample appearances in the different chapters of this book describing case studies of particular classes of proteins and enzymes. In addition, recombination of mutant... 

Recently, a controversial debate has arisen about whether the optimization of enzyme catalysis may entail the evolutionary implementation of chemical strategies that increase the probability of tunneling and thereby accelerate reaction rates [7]. Kinetic isotope effect experiments have indicated that hydrogen tunneling plays an important role in many proton and hydride transfer reactions in enzymes [8, 9]. Enzyme catalysis of horse liver alcohol dehydrogenase may be understood by a model of vibrationally enhanced proton transfer tunneling [10]. Furthermore, the double proton transfer reaction in DNA base pairs has been studied in detail and even been hypothesized as a possible source of spontaneous mutation [11-13]. 

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