stress impact on developmental stability of laboratory rat Rattus norvegicus. [In: Developmental homeostasis in natural populations of mammals: phenetic approach. V. M. Zakharov and A. V. Yablokov, eds]. Acta Theriologica, Suppl. 4: 27-32. Developmental stability of the progeny of pregnant female rats Rattus norvegicus Berkenhout, 1769 kept under different conditions was studied. In two experimental groups, females were exposed to social stress by keeping them in crowded cages at different stages of pregnancy, from the 1st to the 15th and from the 16th to the 21th days, respectively. In the control group, pregnant females were kept under normal conditions. Fluctuating asymmetry of 20 skull characters (number of foramina for small blood vessels and nerves) was used as a measure of developmental stability. Variance of the difference in foramen number between the left and right sides of the skull (1—r) as well as mean number of asymmetrical traits per individual revealed an increase of fluctuating asymmetry in both experimental groups compared with the control group. These results imply the deterioration of developmental stability under impact of social stress.

Rattus norvegicus. [In: Developmental homeostasis in natural populations of mammals: phenetic approach. V. M. Zakharov and A. V. Yablokov, eds], Acta Theriologica, Suppl. 4: 67-72. Developmental stability analysis was conducted for three strains of laboratory rat Rattus norvegicus Berkenhout, 1769 and their hybrids. Developmental stability was estimated by fluctuating asymmetry of 20 characters of skull morphology. A decrease was revealed in fluctuating asymmetry for the inbred strains and for the hybrids of genetically different strains. There were not any differences in fluctuating asymmetry between the homo- and heterozygotes for the separate locus. This support the hypo thesis of the dependence of developmental stability on general genetic coadaptation.