APPEARANCE, FIXATION AND STABILIZATION OF ENVIRONMENTALLY-INDUCED PHENOTYPIC CHANGES AS A MICROEVOLUTIONARY EVENT

Certain phenotypic changes originally induced by direct environmental effects (which can be modelled experimentally) and later reflected by corresponding changes in the genotype (revealed by differences in the reaction of individuals from different populations under the same envi ronmental conditions) highlight one of the main trends in microevoluti onary processes. During that process, a decrease of initially increase d levels of stochastic variation marks the stabilisation of developmen t in a new environment as a change in optimal developmental conditions . Concordance of interpopulation phenotypic differences with experimen tally established dependence on developmental conditions and climatic conditions within habitats signifies the role of environment (by repla cing the modification response within the limits of the reaction norm with a corresponding change in the reaction norm). Disturbances of thi s concordance suggest that some traits of microphylogenesis are playin g a role.