[Requirements imposed on model objects in microevolutionary investigations].

Extrapolation of results of investigations of a model object is justified only within the limits of a set of objects that have essential properties in common with the modal object. Which properties are essential depends on the aim of a study. Similarity of objects emerged in the process of their independent evolution does not prove similarity of ways and mechanisms of their evolution. If the objects differ in their essential properties then extrapolation of results of investigation of an object on another one is risky because it may lead to wrong decisions and, moreover, to the loss of interest to alternative hypotheses. Positions formulated above are considered with the reference to species flocks of fishes, large African Barbus in particular.