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In the evolution literature, sympatric speciation is the origin of two, or more, species from a single local population. Many models have been developed to study the role of ecological competition and sexual selection in sympatric speciation.

In this paper we propose a methodology for systematically deriving efficient computational models to study speciation in populations evolving with overlapping generations. As a particular case, we consider sympatric speciation by sexual selection and we follow an individual based approach: a population is represented as a set of individuals that can mate and survive according to given probabilities.

We use our methodology to construct four different models for sympatric speciation, based on male traits and female preferences. These models differ in the genotypical representation of the individuals. Results of simulations in the different models are shown and discussed.

The study of the models show that sympatric speciation by sexual selection is unlikely, also with a favorable distribution of genotypes in the initial population.

In this study, a new technique is presented for choosing mate chromosomes during sexual selection in a genetic algorithm. The population is divided into groups of males and females. During the sexual selection, the female chromosome is selected by the tournament selection while the male chromosome is selected based on the hamming distance from the selected female chromosome, fitness value or active genes. Computational experiments are conducted on the proposed technique and the results are compared with some selection mechanisms commonly used for solving multidimensional 0/1 knapsack problems published in the literature.

Physically, information carriers are encountered in two occurrences, either in native form as physical structures, or in arbitrarily coded, symbolic form such as signal systems or sequences of signs. The symbolic form may rigorously be associated with the existence of life. In contrast, structural information may be present in various physical processes or structures independent of life. The self-organised emergence of symbolic information from structural information may be called ritualisation. A century ago, Julian Huxley had introduced this term in behavioural biology. Subsequently, this evolutionary key process of the emergence of animal and social communication was studied in depth by Konrad Lorenz, Günter Tembrock and other ethologists. Ritualisation exhibits typical features of kinetic phase transitions of the 2^nd kind. From a more general viewpoint, the origin of life, the appearance of human languages and the emergence of human social categories such as money can also be understood as ritualisation transitions. Occurring at some stage of evolutionary history, these transitions have in common that after the crossover, arbitrary symbols are issued and recognised by information-processing devices, by transmitters and receivers in the sense of Shannon’s information theory. In this paper, general properties of the ritualisation transition and the related code symmetry are described. These properties are demonstrated by tutorial examples of very different such transitions in natural, social and technical evolution, reviewed from the perspective of the emergence of symbolic information and its structural historicity.