ON THE PROBLEM OF VARIABILITY IN REPRODUCTIVE PARAMETERS OF ANIMAL POPULATIONS UNDER TOXIC POLLUTION OF THE ENVIRONMENT

Variability in parameters of reproduction was studied in local populat ions of hole-nesting birds and small mammals inhabiting territories wi th different levels of industrial pollution. The increased stability o f test parameters at some stages of embryogenesis in mammals and of eg g formation and chick growth in birds was revealed. The mechanisms det ermining the level of variation of reproductive parameters are discuss ed. These are: (1) the reaction of heterogeneous population structure, which results in an increased variation at early stages of toxic infl uence; and (2) elimination of defective individuals, which reduces var iation under conditions of high environmental pressures.