Ecological Systems and Devices Annotation << Back NONINTERPRETED BEHAVIOR OF POPULATION DYNAMICS MODELS AND BOUNDARIES OF PARAMETRIC INTERVALS A.Yu. Perevaryukha Discrete models continue to be a widely used tool in mathematical biology. Complex functional iterations are especially popular in models of commercial ichthyology and in applied entomology to describe the dynamics of nonoverlapping generations in salmonid fi sh species or pest butterflies. Opportunities for implementing nonlinear effects in discrete iterative models are redundant. Sharp changes in the behavior of the trajectory occur with a small change in the impact parameter and they are often connected in a cascade with each other. It is difficult to separate one effect from another that is not needed in this model, since all models obey fundamental theorems. In this case, the behavior of the model will lose its essential explainability. The article discusses the delineation of parametric ranges using the example of two well known population models in ichthyology with the opposite interpretation of behavior. Interval delimitation is proposed for the admissible range of values of the model parameters with appearance of a cascade of bifurcations. Keywords: methods for modeling nonlinear effects; substantiation of biological models; interpretation of bifurcations; interval expansion; parametric ranges; adequacy of model properties with control; Allee effect. DOI: 10.25791/esip.06.2021.1232 Pp. 15-23.