Аннотация:Traditional classification of multicellular organisms rests on the analysis of whole amount of morphological, anatomical, cytological, biochemical, molecular, etc. characters mostly of modern organisms. That allows to classify suitably the known objects and in some cases to formulate certain conclusions on the phylogenetic relationship and evolution of groups within particular taxon. However, the conditions of historical similarities and differences between organisms can be diverse. The nowadays data support the great role the convergences and parallelisms play, in spite of ancestor inheritances, in the process of organism evolution. It is evident that the interaction between the genotype and phenotype is the complex multidimensional (non-linear) web of processes including pleiotropy, self-organisation, mechanical interactions and environmental regulative signals contributing to the final organism morphology. At that, the spectrum of real forms has its limitations based not exceptionally upon the presence of exact genes and proteins but is the result of all epigenetic interactions between molecules, cells, tissues and environment realised in the organism development.
In such a case, the morphogenetic approach looks promising for solving the systematic and phylogenetic problems. This approach rests on unrevaling the mystery of form transformation based on the knowledge of possible (allowable) for this group morphogenetic processes, not on discovering of the genetic relations or classification of great number of forms. As an example we analysed the diversity of spatial organisation of shoots in thecate hydroids (Cnidaria, Hydroidomedusa, Leptomedusae). The main tendencies and constraints of evolutionary complexity increase in thecate hydroids colonies are uncovered.
The work was supported by Russian Foundation for Basic Research Grants ## 04-04-48842-а, 05-04-48662-а and 07-04-00736-а.