A central tenet of evolutionary theory is that mutation is random with respect to its adaptive consequences for individual organisms; that is, the production of variation precedes and does not cause adaptation. Several recent experimental reports have challenged this tenet by suggesting that bacteria (and yeast) "may have mechanisms for choosing which mutations will occur" (6, p. 142). The phen...

Inversion mutation is a typical genetic operator for combinatorial problems like the traveling salesman problem (TSP). It reverses the tour between two randomly chosen cities. Here, we propose a self-adaptive variant of inversion mutation. Self-adaptation is a successful control technique for the mutation strength. Up to now, the concept of self-adaptation has not been applied to inversion muta...

Stationary phase adaptive mutation in Escherichia coli is thought to be a mechanism by which mutation rates are increased during stressful conditions, increasing the possibility that fitness-enhancing mutations arise. Here we present data showing that the histone-like protein, HU, has a role in the molecular pathway by which adaptive Lac(+) mutants arise in E. coli strain FC40. Adaptive Lac(+) ...

When mutation rates are low, natural selection remains effective, and increasing the mutation rate can give rise to an increase in adaptation rate. When mutation rates are high to begin with, however, increasing the mutation rate may have a detrimental effect because of the overwhelming presence of deleterious mutations. Indeed, if mutation rates are high enough: (i) adaptive evolution may be n...

The average convergence rate (ACR) measures how fast the approximation error of an evolutionary algorithm converges to zero per generation. It is defined as geometric reduction over consecutive generations. This paper makes a theoretical analysis ACR in continuous optimization. obtained results are summarized follows. According limit property, classified into two categories: (1) linear whose in...

Adaptive mutation to Lac(+) in Escherichia coli strain FC40 depends on recombination functions and is enhanced by the expression of conjugal functions. To test the hypothesis that the conjugal function that is important for adaptive mutation is the production of a single-strand nick at the conjugal origin, we supplied an exogenous nicking enzyme, the gene II protein (gIIp) of bacteriophage f1, ...