V. V. Kotin - Ph.D. (Phys.-Math.), Assistant Professor, Department «Medical and technical information technology» (BMT-2), Bauman Moscow State Technical University

The open system of two interacting populations (main population and subpopulation) is analyzed. Influence of environment is described by introduction of the population flows which intensities are considered as control parameters. Densities of the main population and subpopulation depend on intensities of migratory flows. It is shown that phase-parametric charts illustrate main population equilibrium densities dependence on subpopulation migratory flow with fixed values of main population outflow power. At zero outflow of the density of the main population dependence of equilibrium density of the main population on the power of a migratory flow of subpopulation is smooth. The density of the main population at increase in inflow of subpopulation smoothly falls down to zero. It is shown that for proposed model fold catastrophe is typical. With increase in power of subpopulation migratory flows the interval of steady stationary density of the main population decreases. The upper and low limits of stability interval thus decrease. If the power of migratory flow oversteps the critical limit, the main population is suppressed completely. System reaction on migratory flow growth has catastrophic character.