Ecological and Genetic Models in Population Biophysics

Complex causal relationships occur between population dynamics and a change in a population genetic structure. In our study, a simple model was used to show that the evolutionary process of density-independent natural selection depending on the fitnesses determined by a single diallelic locus can lead to a change in population growth parameters, thus changing the dynamic modes in a population. Possible mechanisms and direction of these changes are discussed. The results clearly demonstrate that the evolutionary change in allele frequencies, accompanied by an increase in the average fitness of the population, may result in the occurrence of cyclic, quasiperiodic, and chaotic modes of population dynamics. The effects observed in our models are largely due to the simple combination (superposition) of the two models: natural selection leads to an evolutionary increase in fitness, and density regulation with an increase in reproductive potential leads to bifurcations that provide various fluctuations in population abundance. However, these fluctuations occur (and manifest themselves) in the course of genetic evolution. At the same time, the combination of models leads to the occurrence of new dynamic modes that are not observed in each of the models separately (i.e., fluctuations in gene frequencies associated with the multimodality of the considered systems and the emergence of new stable attractors).