[Individual variation in the development of the common toad, Bufo bufo (Anura, Bufonidae): I. Timing of development and anomalies of external structure].

Parameters of development have been analyzed in all offspring (1633 ind.) from the same spawn of one pair of common toads under conditions of laboratory rearing, with natural elimination being reduced to a minimum. The results show that the range of developmental options for the species is much wider than it follows from the standard tables of development. "Background anomalies" (Kovalenko, 2003) in the external structure of developing larvae are described and their probable frequencies under nearly optimal conditions are indicated.

[Individual variation in the development of the common toad, Bufo bufo (Anura, Bufonidae): 2. Diagnostic characters of the axial skeleton].

Analysis of individual variation in diagnostic characters of the axial skeleton has been performed in all offspring (1633 ind.) from the same spawn of one pair of common toads under conditions of laboratory rearing, with natural elimination being reduced to a minimum. More than 50 skeletal anomalies have been recorded. Factual data are presented that characterize deviations from the species norm in the frequency of "background anomalies" (Kovalenko, 2003). Correlations between manifestations of different variants of character states are considered. The problem of norm and anomaly in individual variation is discussed.

[Individual variation in the development of the common toad, Bufo bufo (Anura, Bufonidae): 3. Limitations of individual variation and their causes].

The results of studies on the axial skeleton of the common toad (a model species) have been used to analyze factual limitations of individual variations. The results show that the states of the studied characters do not freely combine with each other but are subject to certain morphogenetic limitations. The causes of most these limitations have been revealed during the study. Classification of the main factors limiting individual variation in the course of development is presented.

[Regularities of morphogenesis of the sacrourothelial joint in Anura].

The regularities in the formation of different types of Anura sacrourothelial joints have been determined. A review of factors that affect the form of this joint is presented. It has been established that the determinant role in the formation of a moveable or immoveable joint is played by the topography and time of the appearance of musces in the sacrourothelial area. The proposed mechanisms explain not only the diversity of structural norms depending on this feature, but also options of individual variability.