ИСТИНА

During the last decades, the traditional, morphology-based evolutionary biology has been challenged. Molecular systematics and phylogenetics were considered as “advanced” fields compared to the “old-fashioned” comparative morphology and the search for homology,links between different structures and organizations, and evolutionary interpretations. Even synapomorphy-based Hennigian thinking was abandoned because of the advent of computer-based phylogenetic studies. From morphological or molecular data sets, mathematical and statistical approaches may produce thousands of different tree hypotheses, depending on minor modifications of the primary data set, methods of calculation and setting of parameters. Still, selecting organisms for study, molecular systematics depends on traditional systematic hierarchy. Relationships inferred from molecular markers, however, often violate all taxonomic and biological knowledge that accumulated during centuries. Any organism is an extremely complicated dynamic morphological and molecular network and never existed only as a reproducible (mature) stage alone but always only as an ontogenetic (life) cycle of various degrees of complication. Under this approach evolution is not an endless stream of various characters changing in any directions but instead in every geological epoch operated only within a particular organism organized in a particular species which are always existed only as a more or less closed functional cycle. Strictly speaking, beyond such cycle of functioning within complex networks, life does not exist. It may therefore sound somewhat paradoxically, but despite on all modern progress in the field of phylogenetics, a general theory of the organisms’ shape change is still lacking.Without such a theory, phylogenetics will always remain as a formal science of the formal genealogical investigations either based on the morphological characters selected from already constructed taxonomic hierarchy or on the nucleotide sequences. If we aim to build real reconstructions of past states of any biological structures and processes, i.e. evolutionary history (phylogeny) in strict sense, we need to search for actually existing and directly observable processes which are underlying the change of shapes of living organisms. Ontogeny and its shifts are the only real processes of this kind and we cannot skip it in our considerations. The links between evolution, ontogeny, systematics and phylogenetics are prima facie obvious, but similarly greatly underestimated currently, though the field of the “Evo-devo” is growing continuously. As a synthesis (or more exactly, re-synthesis) of still in considerable degree developed, independent major biological fields, i.e. ontogeny, evolution and taxonomy, the new conception of ontogenetic systematics is therefore suggested and illustrated by various examples from different animal phyla and especially including nudibranch molluscs. Dorid nudibranchs are one of the best animal groups to illustrate problems of the current cladistic paradigm and the potential productivity of the ontogenetic approach. Numerous data of traditional systematics and our novel morphological and ontogenetic data have been employed in order to construct a reliable model of the ancestral dorid ontogenetic cycle. None of the ontogenetic cycles disappeared completely in evolution without leaving traces in the descendant ontogenesis. Without knowledge about such traces, e.g. gill slits in the terrestrial mammals’ embryos, tadpole larvae in apparently “primitive” sessile ascidians or larval shell in completely shell-less adult nudibranchs, phylogenetics would have become a science without true history. However, Ernst Haeckel’s prophetic suggestion to name such traces as recapitulations and the importance of heterochrony for animal evolution is still greatly underestimated in modern science.