No abstract

namely, the order-disorder conflict. Order, represented by a minimum of the free energy in physical systems, is related to the Darwinian principle of survival of the fittest; disorder, or entropy maximization, is driven by temperature in physical systems and genetic mutations in biological systems.The Penna model for biological aging 2 is based entirely on Darwinian evolution with mutations and is a representation of the Darwinian conflict particularly well suited for computer simulations. It has played a role similar to the Ising model for magnetic systems in the sense that it is a minimal model that retains only the essentials of Darwinian dynamics. Like the Ising model, it uses binary variables to represent genes: zero for ordinary genes and ones for harmful ones. Originally focused on problems of biological aging, application to several different evolutionary problems substantially increased its scope. Our purpose here is to provide an updated review of recent results researchers have obtained with this model. 74Copublished by the IEEE CS and the AIP

We study the plausibility of the handicap principle, using a bit-string model to represent both the genoma and the phenotype of the individuals of a population. We find that the distribution of genoma of population selforganizes due to the natural selection. The phenotype represents some trait of the interaction of individuals with others and with the environment so, it also suffers the pressure of natural selection. The handicap is introduced in sexual selection. At time of reproduction, females compare males according to the phenotype, choosing the one who has a phenotype representing the greatest handicap. Our results show that in this way females are able to see the quality of their possible mates and males have no possibility to cheat due to pressure of natural selection.

A one dimensional non-equilibrium stochastic model is proposed where each site of the lattice is occupied by a particle, which may be of type A or B. The time evolution of the model occurs through three processes: autocatalytic generation of A and B particles and spontaneous conversion A → B. The two-parameter phase diagram of the model is obtained in one-and two-site mean field approximations, as well as through numerical simulations and exact solution of finite systems extrapolated to the thermodynamic limit. A continuous line of transitions between an active and an absorbing phase is found. This critical line starts at a point where the model is equivalent to the contact process and ends at a point which corresponds to the voter model, where two absorbing states coexist. Thus, the critical line ends at a point where the transition is discontinuous. Estimates of critical exponents are obtained through the simulations and finite-size-scaling extrapolations, and the crossover between universality classes as the voter model transition is approached is studied.

Using a bit string model, we show that asexual reproduction for diploids is more efficient than for haploids: it improves genetic material producing new individuals with less deleterious mutations. We also see that in a system where competition is present, diploids dominate, even though we consider some dominant loci.