Directional variability of counting features of the axial skeleton of roach Rutilus rutilus (L.) in the conditions of urbanization: formation of urban morphotype

In the Chemoshur pond located on the Izhevsk suburb the roach had statistically significant differences from the roaches of other urban and suburban ponds of the Udmurt Republic in four counting features of the axial skeleton. Such differences are corresponded with the characteristics of "industrial race" of this species. Only in this pond a periodic death of the individuals of roach of one-year age was marked, coin-ciding in time with the spring increase in the level of its chemical pollution as a result of the flow of melt water from the urban area. The juveniles of roach surviving in the spring also had statistically significant differences from the dead individuals of the same age in complex of counting features of the axial skele-ton. Based on the results of visual observations of the living and dying juvenile individuals of roach in the retaining zones of the pond, an assumption was made about the functional mechanisms of selection for survival associated with differences in their locomotor activity in the spring period in conditions of water pollution.