EN
It was proved many times that the selection leaded in the direction of one trait can also influence on other. One of the most frequently selected trait is body weight which is easy to measure. In this experiment, mice from three lines were used. Two of them were divergently selected on body weight at the postnatal day 21 (light and heavy lines) for over 135 generations. The third line were the control line without any selection. The animals were observed in the social testing apparatus which is used for perform two behavioral tests: sociability and preference for social novelty tests. The results show that selection on body weight influenced the social behavior of laboratory mice. Individuals from the heavy line (both sexes) showed minor modifications of the natural behavior in the sociability test (P<0.05). Additionally results of females from the heavy line demonstrated some disorders in social novelty test (P<0.05).