Review and assessment of the significance of scientific works by I.V. Zmitrovich, devoted to the processes of biological development and eukaryote megataxonomy

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Introduction

A multitude of investigations into flora and fauna, carried out in Russia and internationally, are dedicated to elucidating the biological development of living organisms, both animals and plants. Systematics, in the prevailing view, represents both the fundamental basis and the crowning achievement of biology [1]. Systematists, who synthesize the competencies of ecomorphologists and evolutionary biologists, assume a critical role as theoretical biologists, interpreting the planet’s biodiversity in its genesis and progression.

The study of I.V. Zmitrovich’s bibliographic corpus has revealed that his research was significantly concerned with key theoretical biological concepts such as morphogenesis, adaptogenesis, and the megasystematics of eukaryotes. In particular, I.V. Zmitrovich’s principal area of interest was focused on fungi – chlorophyll-devoid osmoheterotrophic organisms with rigid chitinous cell walls and open systems of growth, which exhibit a resemblance to plants, leading to their prolonged classification within this kingdom. Nevertheless, his investigation of trends in the development of multicellularity and the modular theory extended his research scope to include the evolution of the vegetative body in plant organisms, particularly in higher plants characterized by various cell types and tissue differentiation (for instance, connective tissue and mechanical tissue) [2]; the structure of higher plants exhibits organization into distinct organs, including roots, stems, leaves, and flowers [3].

Eukaryotes – a heterogeneous assemblage of organisms encompassing a broad spectrum of plant lineages, gastrulated animals, and fungi – are characterized by the possession of a structurally defined nucleus and, in the predominant majority of aerobes, mitochondria of α-proteobacterial origin. Photosynthetic eukaryotes harbor plastids derived from endosymbiosis with cyanobacteria or from secondary endosymbiotic events with other eukaryotes containing cyaneae-derived plastids [4].

Demonstrating a remarkable heterogeneity in both structure and function, eukaryotes constitute a propitious field for the advancement of biology’s theoretical constructs. The genesis and evolutionary trajectory of cellular organelles, the emergence of multicellularity (including its polyphyletic origins and distinctive traits in different taxa) and multicellular aberrations (such as cancer biology), the particularities of histoarchitecture within diverse lineages, and evolutionary morphology are all issues examined by specialists who engage with the interdisciplinary field of eukaryotic evolutionary biology.

Within the scientific corpus, authors articulate a range of, and occasionally discordant, definitions associated with the processes of morphogenesis in broad taxonomic groups [5–7].

It is our considered opinion that we should explicate the ensuing definitions, concepts, and nomenclature, which, in our estimation, most accurately capture the scientific paradigms for the study of biological developmental processes in eukaryotes and which have been implemented throughout this article’s development.

Morphogenesis refers to the processes that are genetically determined but carried out through epigenetic interdependencies of cells and their complexes [8]. Thus, morphogenesis represents a dynamically changing process and is one of the three fundamental aspects of developmental biology [9].

Adaptogenesis refers to the set of processes involving the emergence, development, and transformation of morphophysiological changes that provide adaptations during evolution, aimed at ensuring the survival and reproduction of organisms in changing environmental conditions [10, 11].

Ecotypic differentiation is the establishment and reproduction of ecotypes, i. e., groups of organisms whose constitutional features most fully correspond to the ecological regime of the habitat they occupy. Ecotypes can vary in scale, ranging from an individual adapted to a local habitat to clines occupying a wide distribution [12, 13].

The problem of rank delineation in systematics remains a subject of debate and unresolved conclusions, even in light of progress within molecular taxonomy and cladistics. Our research includes the collaborative development of methods for rank harmonization in the classification of eukaryotes, with the goal of creating a system that offers the maximum predictive capabilities currently possible.

It is our considered view that this article should appropriately acknowledge Dr. I.V. Zmitrovich, a Doctor of Biological Sciences and a Leading Research Fellow at the V.L. Komarov Botanical Institute of the Russian Academy of Sciences, who reached the age of 50 on June 1, 2023, and whose professional and personal life, as demonstrated through our analysis of his scientific output, are inextricably intertwined.

The corpus of works in which I.V. Zmitrovich has been involved is considerable, with particular emphasis on those publications that engage with theoretical biology, encompassing the theory of morphogenesis, megasystematics, issues of adaptogenesis and speciation, and cancer biology. Within the register of the mycological systematist community, his surname is denoted in the abbreviated form of Zmitr. [14].

Numerous colleagues – both Russian (V.I. Vasilevich, N.N. Tzvelev, S.P. Arefiev, G.P. Yakovlev) and foreign ones – highly valued I.V. Zmitrovich as a rare representative of theoretical biology among cryptogamic botanists. He corresponded with E. Parmasto, S.P. Wasser [15], A.G. Savostyanov, Z. Pouzar, J. Boidin, T. Cavalier-Smith [16, 17], and E. Nevo. From 2004 to 2011, at the invitation of S.P. Wasser, he visited Israel multiple times as a mycologist expert for a project on cryptogamic flora.

The flux of scholarly output in the domain of theoretical biology has undergone considerable intensification during the preceding decade, which does not invariably enable current investigators to efficiently and thoroughly examine and implement the advancements made by scientific collectives and individual researchers.

Consequently, this review aims to explore and introduce our readership to the extensive body of scientific work by I.V. Zmitrovich focusing on the processes of morphogenesis and adaptogenesis in eukaryotic organisms, thereby making a modest contribution to enhancing the utilization of scientific and technical information among researchers.

Discussion

Morphogenesis

I.V. Zmitrovich is the author of several remarkable works devoted to the study of forms, structures and adaptations of plant organisms in a discourse that can be conventionally designated as “plant form philosophy”.

Systematization of morphological phenomena. I.V. Zmitrovich was the first to propose an “marrowbone” differentiation of morphological phenomena, identifying such categories as planimorph, tectomorph and stylomorph. These three categories help to clearly distinguish between the types of convergent formations.

Planimorphs are superficial convergent formations in organisms with fundamentally different body plan.

Tectomorphs are characterized by homogeneity of morphogenetic modules, indicating convergent phenomena that arise due to common morphogenetic mechanisms.

Stylomorphs, like planimorphs, characterize a superficial similarity, imposed, however, on a certain “tectomorphological basis”. In this aspect, the stylomorph concept correlates well with the concept of ecotype, but is not tied to intraspecific polymorphism (as stylomorphs can be interpted ecotypes, species, genera, and even morphotypes characterizing taxa of a higher rank).

Patterns of morphogenesis. The Earth’s gravitational field, which encompasses all living and nonliving things, determines a number of “amazing analogies”. In plant organisms, this is expressed in the tendency toward a spiral-conical arrangement of axial structures, which leads to the formation of a stable superstructure filled to the maximum with morphogenetic modules, especially noticeable in terrestrial forms.

The general pattern of growth, consisting in the regular filling of space and mutual repulsion of new structures, leads to dichotomization, observed both in plants and in budding animals and crystals. This purely geometric pattern becomes an important tool for the analysis of planimorphogenesis.

In autotrophic plants, the main factor of polarization, differentiation of the vegetative body and “scattering” of competing shoot systems is sunlight, while in fungi the “scattering” of competing mycelia occurs within the nutrient medium. In general, the phenomenon of “scattering” of self-repeating structures can be formalized as “blowing” of the “Pythagorean tree” by a “stochastic wind”.

Tectomorphic analysis, proposed by I.V. Zmitrovich, allows us to clearly identify morphogenetic material, which is not “plasticine from which the environment can mold anything”, but determines the limits of morphogenesis. This is often ignored in the context of the abstract concept of “ecomorphs”. For example, despite obvious parallelisms in the world of algae, the colonization of land was possible only for green algae with phragmoplast, which emphasizes the importance of the structural features of the morphogenetic material.

Stylomorph is a very indicative object for ecomorphology, allowing to analyze the transformation of tectomorph under the influence of individual ecological factors and their series.

Three-stage evolution of plant form. I.V. Zmitrovich developed the concept of three-stage evolution of plant form [18]. In megaevolution of plant form I.V. Zmitrovich proposes to distinguish three key stages of organization, which he calls “protophytes”, “cladophytes” and “telophytes”.

1. Protophytes – at this level, primitive self-similar structures are formed, which are characterized by elementary (unicellular) organization. The “alienated product” deposited outside (cell wall) predetermines the main line of plant evolution – the formation of linear (and derivative) cellular aggregates.
2. Cladophytes are the next level, where aggregation and integration of structures is observed, providing greater stability and functionality. Cladomes are morphogenetic material for the formation of multifilamentous, pseudoparenchymatous and parenchymatous plant tissue architecture.
3. Telophytes are the third level, where the process of integration and differentiation is completed. The telome (cormus) is a mosaic of “multicladomes”, which at a new level repeats the behavior of “vegetal” structures (growth, morphological differentiation, plant type of spatial expansion of shoot systems).

One of the key patterns of plant structure is the regular filling of space with self-similar structures of various dimensions:

cells → cell colonies → cladomes and their derivatives.

Telomes are the higher form of plant evolution, where maximum integration and diversity of functions occur.

All three levels are characterized by open growth, which differs significantly from the closed growth observed in gastrulated animals. Open growth ensures constant expansion and formation of new structures that enhance the interaction of the organism with the environment. Regulation of the formation of plant organisms varies from non-centralized, where individualization becomes rather problematic, up to quasi-centralized one.

At all levels of evolution, a common trend is observed: increased integration of modules and their irreversible differentiation, which leads to an increase in “ecomorphological subjectivity”.

I.V. Zmitrovich in his works offers an integrative approach to the study of plant forms, arguing that the analysis must be built in accordance with a three-stage scheme. A clear distinction between the main spheres of morphological phenomena (planimorphs, tectomorphs and stylomorphs) allows for a deeper understanding of the patterns of evolutionary development and adaptation of plants [18, 19].

“Insolation niche”. Morphogenesis of polypores. I.V. Zmitrovich also has a special theory of morphogenesis of the fruiting body of polyporalean tinder fungi (“insolation niche hypothesis”), which he outlined in his doctoral thesis [20]. It explains well various deviations in the development of fruiting bodies of tinder fungi. This hypothesis helps to understand how various external factors can influence the development and morphology of fungi.

According to I.V. Zmitrovich, “insolation niche” is an area above the substrate, which temperature and humidity conditions promote apical growth of the fruiting body node and its transition to radial growth at the boundary of the optimum zone.

1. At the beginning of the process of development of the fruiting body, the conditions of the insolation niche provide an ideal balance of temperature and relative humidity for the apical growth of the rudiment of the basidiome.
2. As the relative humidity level changes and the negative impact of ultraviolet radiation increases, the surface hyphae begin to stop their active growth. This leads to the formation of protective structures that protect the developing hyphae and their spores from unfavorable conditions.
3. Under the protection of these structures, unsclerified hyphae keep their activity to building of spore-protecting structures. This process serves as an indicator that the aerial mycelium is moving into a “pessimum zone”.
4. Peripheral hyphae that retain the ability to grow continue to form the basidiome, creating additional cycles of overbuilding. However, their growth occurs in a direction approximately perpendicular to the original growth direction.

The insolation niche hypothesis demonstrates unique aspects of fungal development and also opens up new horizons for research in the field of biomorphology and ecomorphology of these organisms [20] (Fig. 1).

 

Fig. 1. Schematic representation of the development of the basidioma (A) and hymenophore (B) of Microporus xanthopus and interpretation of morphogenesis in light of the concept of an insolation niche [20]

Рис. 1. Схематическое изображение развития базидиомы (A) и гименофора (B) Microporus xanthopus и интерпретация морфогенеза в свете представлений об инсоляционной нише [20]

 

At the same time, according to I.V. Zmitrovich, the ideas about the influence of the state of the substrate and insolation on the morphogenesis of the basidiomes of polypores are complementary (Fig. 2).

 

Fig. 2. The main factors influencing the morphogenesis of basidiomes of polyporaceous fungi and epiphenomena of their interaction: 1 – hydrothermal regime, 2 – evaporation intensity, 3 – microclimate, “insolation niche”, 4 – daily fluctuations, 5 – daily heating of the substrate. Morphogenetic effects: I – initiation of primordia, II – energy of expansion of aerial mycelium, III – hygrotropism (+/–), IV – phototropism (+/–), V – histogenesis [20]

Рис. 2. Основные факторы, влияющие на морфогенез базидиом полипоровых грибов и эпифеномены их взаимодействия: 1 – гидротермический режим, 2 – интенсивность испарения, 3 – микроклимат, «инсоляционная ниша», 4 – суточные колебания, 5 – дневное прогревание субстрата. Морфогенетические эффекты: I – инициация примордиев, II – энергия экспансии воздушного мицелия, III – гигротропизмы (+/–), IV – фототропизм (+/–), V – гистогенез [20]

 

Monograph by I.V. Zmitrovich “Epimorphology and tectomorphology of higher fungi”. In his monograph “Epimorphology and tectomorphology of higher fungi” [19], I.V. Zmitrovich summarizes his ideas over morphogenesis realm. In addition, the work presents a narrative covering and analyzing the scientific contribution of outstanding phytomorphologists of the 20th century, such as E. Corner, M. Chadefaud, M. Locquin and H. Clemençon. This work not only recapitulates their achievements, but also dives into the depth of the generalization of the problems of morphogenesis that were developed by these researchers.

1. Corner is a famous phytomorphologist and mycologist of the 20th century, who is the author of the Сlavaria-hypothesis of the evolution of the fruiting bodies of basidiomycetes, a critic of the “new morphology”, and an original morphologist of palms. His works were distinguished by their lapidary nature, and their schemes were fundamentally inflexible. Corner’s commitment to the doctrine prevails over his openness to the new, and in this sense his legacy is useful rather for its negative experience.
2. Chadefaud is a cryptogamist-encyclopedist, who enriched general morphology with ideas about cladomes – aggregates of filaments in which the leading axis with accessory axes (pleuridia) stands out. Initially developed on the material of red algae-florideae, the concept of the cladome was later extended by him to fungi, lichens, brown algae, as well as to the structure of cormophytes.
3. Locquin is a mycologist-encyclopedist, morphologist, philosopher, who made a variety of contributions to morphology, known for his elaborated sporoderm classification.
4. Clemençon is a leader in descriptive morphology and plectology of fungi; he is the author of the concept of blemas, the types of development of various agaricoid basidiomes are described him in detail. He is especially famous for his fundamental work “Cytology and plectology of Hymenomycetes”.

In the Zmitrovich’s narrative, an invisible thread is traced that connects these four scientists, who generally did not intersect in their scientific activities. This allows him to create a new contextual field for discussing current problems of morphology and morphogenesis and to talk about a synthesis that opens up new horizons for further research in the field of ecology, taxonomy and biomorphology [19].

Adaptogenesis

Adaptogenesis is a complex and multifaceted process that includes the integration of cellular and population adaptations as well as morphological changes that occur as a result of these processes. The works by F.Z. Meerson and N.N. Iordansky, on which I.V. Zmitrovich relies, represent an important basis for studying adaptive mechanisms and their influence on evolutionary changes [21, 22]. Figure 3 in this context can serve as a clear illustration of Zmitrovich’s concept.

 

Fig. 3. Factors, levels and morphofunctional results of adaptogenesis according to I.V. Zmitrovich. Arrows reflect cause-and-effect relationships and mediated blocks, straight lines – the connection of concepts [20]

Рис. 3. Факторы, уровни и морфофункциональные итоги адаптациогенеза по И.В. Змитровичу. Стрелки отражают причинно-следственные связи и опосредованные блоки, прямые линии – связь понятий [20]

 

According to the concept proposed by I.V. Zmitrovich, the key determinants of adaptogenesis are an unstable environment and a set of “selection filters”. At the cell level, selection occurs according to adaptively significant variants of non-coding DNA, which serve as the basis for molecular pre-adaptation. At the level of tissue differentiation, histional differentiation plays an important role. Histion (a term by G.A. Savostyanov) is a kind of “production team” – a set of cells with differentiating functions and the main morphogenetic module at the tissue level of organization. Cell responses realized at this level underlie evolutionary changes in tissue architecture. At the level of the organism, differentiation of constitutional types, ecotypes, is of great adaptive significance. The ecotypic population is the material for speciation. At the supraspecific level, the subjects of adaptogenesis are morphotypes and body plans.

During development of aforementioned problems and, in particular, the cell adaptation, I.V. Zmitrovich came up with an interesting scheme of carcinogenesis as an imbalance of the “adaptive blocks” of the cell, associated with the unpacking of protozoan “survival programs”, associated in turn with the activation of the cytoskeleton (proliferation) and heat shock proteins (blocking of apoptotic pathways) (Fig. 4).

 

Fig. 4. The pattern of imbalance between the main adaptive intentions of multicellulars’ cell (on black background), which leads to carcinogenesis [23]

Рис. 4. Схема баланса основных адаптивных интенций клетки многоклеточных организмов (выделены белым шрифтом на черном фоне), и возникающего дисбаланса, приводящего к канцерогенезу [23]

 

Genecological problems development

I.V. Zmitrovich revived interest in the long-undiscussed problems of genecology, developed at the beginning of the 20th century by Turesson [24]. A modified manifestation of a trait that occurs in specific environmental conditions is defined as an ecophene. This term describes how certain adaptive characteristics can change depending on the influence of environmental factors, such as temperature, humidity or other ecological and physiological conditions [24].

An organism that is clearly associated with a specific environmental situation is called an ecade. An ecade is characterized by a deviation from the norm of individual traits of an organism that does not affect its constitution, which complicates the task of identifying them in the natural environment. In practice, ecades are rarely found in pure form, since they are the result of specific ecological and genetic interactions.

Organisms exposed to a constant complex of environmental factors form certain constitutional types called ecotypes. These ecotypes are in equilibrium with the ecological regime of a specific habitat and are the result of adaptation processes. Ecotypes are characterized by:

• Adaptation to specific conditions: ecotypes become adapted to certain climatic or ecological environments, which allows them to successfully survive and reproduce.
• Genetic diversity: it is important to note that within ecotypes, variability in a number of traits can be preserved, which allows them to remain dynamic and adaptive to changes in the external environment.

E.N. Sinskaya made a significant contribution to the study of ecotypic differentiation, defining an ecotype as a group of populations that have a common origin and are adapted to specific conditions within a certain climatic region. These populations are capable of self-reproduction under conditions of a constant complex of environmental factors and have similar morphobiological traits, but acceptable variability in other characteristics [25, 26].

I.V. Zmitrovich emphasizes that the discussion of ecotypes should be based on an understanding of the molecular mechanisms of adaptatiogenesis. These mechanisms are associated with the choice of cell lines between proliferation, differentiation and apoptosis within the framework of various “cell responses”. He draws an analogy between the concept of isoreagent in Turesson’s terminology, proposing to compare the role of ecotype with how isoreagents influence genetic variability and population adaptation.

Thus, ecotypic differentiation is an important aspect of adaptatiogenesis. It not only reflects the relationship between the morphological and ecological characteristics of organisms, but also opens up new horizons for understanding evolutionary processes. The study of ecotypes and the molecular mechanisms associated with them helps to create a more complete understanding of the adaptive strategy of organisms in a changing environment.

Adaptive changes within the framework of the genetically determined norm of the organism’s reaction can create an illusion that ecotypes are unpromising formations from the point of view of evolution. Such a view ignores the importance of the time factor, which plays a key role in ecotypic differentiation and evolutionary changes within populations. The time aspect has two important sides in the context of adaptations and the formation of ecotypes:

• Constant reproduction of ecotypes in certain habitats can lead to the fact that ecotypes with specific adaptive characteristics will sooner or later displace forms approaching the “average norm”.
• With reproduction of such a situation in generations, an accumulation of genetic changes occurs within the population, including statistically significant “filling” of certain ecotypes with various mutations [27].

These changes enhance the adaptive advantages of ecotypes, allowing them to compete more effectively for resources and survive in specific conditions. The ecotypes themselves can become the subject of natural selection, which leads to the fixation of adaptively significant chromatin variants responsible for the regulation of gene expression [28].

An ecotypic population is a system that, due to the heterochronicity of the processes occurring in it, is genetically heterogeneous, but at the same time retains a certain set of features in a dynamic state. It is in this dynamic process that the splitting of isoreagents into ecoelements (constitutional types, genetically fixed to varying degrees) and ecophenes (genetically unfixed constitutional shifts, the carriers of which gradually disappear from specific habitats as ecotypes are fixed and spread, accompanied by genetic restructuring of the corresponding population) occurs [29].

Closely related to the problem of ecotypic differentiation is the issue of the need to develop a system of taxonomic designations for adequate, at a specific stage of knowledge, description and hierarchical organization of intraspecies polymorphism. The category of subspecies most accurately corresponds to geographically isolated macropopulations. The category of variety (varietas) in taxonomic practice is usually used to designate an ecotype, and the category of form (forma) is used to designate an ecophene or an ecada [30]. It should be emphasized that from a morphological point of view, ecotypes may well correspond to traditionally understood species due to the frequently observed break with the abstract average type of the latter. Usually, the “herbarium species” that were initially described on the basis of a single specimen turn out to be ecotypes of polymorphic species. In addition, some regional ecotypes of fungi, widely represented in their characteristic habitats within the range, were initially described as separate species (Fig. 5).

 

Fig. 5. Aspects and concepts of species in taxonomy. Lines reflect the relationship of concepts. The correlation of the concepts “ecospecies/phylospecies” (highlighted by a double frame), increasingly successful in connection with the development of methods of molecular taxonomy and comparative genomics, provides important material for the theory of speciation and adaptogenesis [20]

Рис. 5. Аспекты и концепции вида в систематике. Линии отражают взаимосвязь понятий. Корреляция понятий «эковид/филовид» (выделены двойной рамкой), все более успешная в связи с развитием методов молекулярной систематики и сравнительной геномики, дает важный материал для теории видообразования и адаптациогенеза [20]

 

The status of such taxa was downgraded to intraspecific relatively recently, after it became possible to assess the level of divergence by comparatively studying nucleotide sequences in phylogenetically informative regions of the genome, primarily genes and intergenic spacers of the rRNA-encoding cluster. For fungi, the most informative locus at the species level was empirically determined as the internal transcribed spacers ITS1 and ITS2, located on both sides of the 5.8S gene (which turned out to be very conservative and its nucleotide sequence does not carry any phylogenetically significant information in closely related species and intraspecific lineages). At the same time, in approximately two-thirds of the studied fungi, the intraspecific variability of the ITS1–ITS2 sequences fluctuates within 0–1%, and in approximately three-quarters – within 1–2% [31].

However, as noted by I.V. Zmitrovich, “..It should be noted that the ‘phylogenetic bush’ corresponding to the species units-linneons can be very confusing and isolation barriers are not formed between all series of parallel ecotypes. Sometimes, morphologically sufficiently distinct, but reproductively not isolated ‘cores’ are recognized within the linneons, and sometimes divergence is recorded only by molecular methods. The current consensus of specialists on both such taxa-linneons and on more splitted units using various methods is associated with the awareness that these objects are in a state of reconstruction and the names used are rather ‘pragmatic units’, unions, the correspondence of which to phylo-species has yet to be revealed”.

Eukaryote megasystematics: theoretical bases and approaches

Megasystematics represents a part of biological systematics that studies the largest divisions of the organic world, in particular, eukaryotes. This direction contributed to the formation of a deeper understanding of the classification of eukaryotes using various methods and approaches, which determines its relevance and importance in the biological sciences [32–35].

Historical context and development of megasystematics. The foundations of megasystematics were laid by many scientists, including K.S. Merezhkovsky and E. Chatton, who in the mid-20th century were engaged in the study of phylogenetic and classification constructions using the concepts of kingdoms and phyla [36, 37]. During this period, experimental systems of eukaryotes competed, which sought to create universal references for their classification [38, 39].

The use of a multi-kingdom system of eukaryotes was proposed by R. Whittaker, which was a significant step in understanding the systematics of this level [40].

Methodological approaches of I.V. Zmitrovich. I.V. Zmitrovich joined the discussion of megasystematics at a time when methods of phylogenetic reconstruction had already begun to acquire objective foundations thanks to multilocus and whole-genome comparisons of the primary DNA structure. However, the rank structure of the megatree of life still remained a subject of subjective assessments, largely determined by the logical foundations of the “Linnaean hierarchy”.

The co-ordination of different authors regarding the ranks of taxa is carried out in different ways, depending on:

1. The nature of the taxonomic sample, because the size and composition of the sample can significantly affect the possible results of data interpretation.
2. The flexibility of the authors in using insertional taxonomic categories along with the main ones.

I.V. Zmitrovich identifies a methodologically questionable procedure in cladograms ranking, namely postulating a direct correspondence between the sequence of the main dichotomies of the phylogenetic tree and the main categories of the “Linnaean hierarchy”. This understanding does not take into account the complex processes underlying speciation and the formation of higher taxa. I.V. Zmitrovich is of the opinion that speciation and the formation of higher taxa are a consequence of the elimination of a part of the spectrum of ecotypic polymorphism, which is generally random. He suggests correlating the main categories of the “Linnaean hierarchy” with large phylogenetic radiations that provide a high concentration of nodes within one “zone” of the phylogenetic tree. A terminal radiation better corresponds to a taxon of a lower rank, a basal radiation to a taxon of a higher rank. In the presence of incomplete samples, it is more justified to “approximate” distant nodes to the nearest radiation, instead of formally assigning them equal rank [20, 41].

The first “experimental megasystem” by I.V. Zmitrovich received some resonance in 2003 [42]. The work postulated the antiquity of metamonads and euglenozoans (which has again become mainstream in recent years), the origin of cryptist and haptic plastids as a result of “tertiary endosymbiosis” (which is also not excluded today), and also made the first attempt to lower the rank of some subdivisions of Metazoa.

Conclusion

The list of works in which I.V. Zmitrovich participated is extensive, and a special place in it is occupied by works touching upon issues of theoretical biology (theory of morphogenesis, megasystematics, issues of adaptogenesis and speciation, cancer biology) (see Appendix for a detailed list).

In the course of the study, the importance of using the rank balancing method, effective for the systematics of eukaryotes, was established, which was demonstrated in the studies of I.V. Zmitrovich.

Our collaboration with I.V. Zmitrovich in the field of megasystematics of eukaryotes resulted in a number of publications [43–45]. In a number of them, the problem of rank correlation of higher taxa of eukaryotes is raised and a number of groups in a new rank are formally described.

In our opinion, the materials presented in the review allow us to acquaint our readers with numerous scientific works of I.V. Zmitrovich, and make a modest contribution to the optimization of the work of researchers of the biological development of eukaryotes with scientific and technical information.

About the authors

Vladimir V. Perelygin

Saint Petersburg State Chemical and Pharmaceutical University

Author for correspondence.
Email: vladimir.pereligin@pharminnotech.com

Doctor of Medical Sciences, Professor, Head of the Industrial Ecology Department, Editor-in-Chief, Publishing House Northwestern Institute of Biomedical Problems and Environmental Protection

Russian Federation, Saint Petersburg

Mikhail V. Zharikov

Saint Petersburg State Chemical and Pharmaceutical University

Email: zharikov.mihail@pharminnotech.com

Senior Laboratory Assistant at the Department of Industrial Ecology

Russian Federation, Saint Petersburg

References

Supplementary files