Summary

The evolutionary theory is usualy regarded as making a claim to the deterministic prediction answering the questions: what will occur under the given environmental influences, how this will occur and when? This claim seems to be far from reality when we are taking into account the complexity of the relationships between the organisms and their environment, as well as the probability of the evolutionary process itself. However, as for as selective vector exerts an effect if (and only if) the adaptation of the organisms progresses, it is possible to make use of the extrapolation. Even provided that we are ignorant in some environmental parameters, as well as in some peculiarities of the organization (and ontogenesis) influencing the direction of evolution, yet there is a possibility to distinguish among them the most effective agencies providing the basis for the prediction of the direction and even the rates of evolution. Remind that such a prediction presents the essantial body of the artificial selection. This prediction fits the study of the phenotypes and their reactions, rather then the study of the genotvpic variability. This viewpoint is based on the impossibility to estimate the selective advantage even for the Mendelian allele, not to mention the polygenic characters.

Furthermore, the impossibility of determination of selective coefficients, as well as the relative adaptive value and (or) fitness, is due to the fact that the stability of morphogenesis is higher then that of genotypes.

Nevertheless, the prediction of the direction of evolution is of great practical importance. Remind for example phenomena of the "antropogenic evolution" - the adaptations of pests to the pesticides, resulting in the accumulation of these substances at the higer trophic levels in the ecosystems; or arising of the antibiotic - dependent pathogenic myco - and microflora in people, domestic animals and cultured plants; or synantrophisation of wild animal and plant species e. t. c. The consequences of the evolutionary processes of this kind have to be predicted first of all due to their harmful environmental impact which require the significant investments to mitigate them.

This book is concerned with the analysis of causes that allow for the direction of micro - and macroevolution as well as for the correlation between the evolution of organism and evolution of ecosystems.

The direction of microevolution is guided by two main agencies: variability and environmental conditions. The common idea, that it is selection that determines the direction of evolution is not to be fairly true. In fact, the direction of the selection is to be derived from the variability and environmental impact, the last being brought about through the stress of the struggle for life. The pheno- typical variability, more exactly its genotypical component, which affords both the material and gidance of evolution, is extremely diverse. In every given generation the evolution is concerned with only those part of genofond, which are manifested of the phenotipic level of the individuals without making the selection to act against them. The ways of expression of variability, as well as their changes in the process of evolution, depend on the lot of parameters determining the fate of the evolving characters...

There occurs the continuous range of shifts between the stable genotypically determined phenotypic characters and the phenotypical characters with the wide reaction norm. Characters of these two opposite types imply fairly different mechanisms of the evolution. The evolution of the strictly determined characters is based on the elimination of the unfavorable inheritable deviations (i. е., deviations which does not fit the direction of the environmental changes), as well on the combinations of those deviations which fit the direction of the selection. The evolution of characters with wide reaction norm is based on the formation of geno- copies of favourable phenotypes, i. e. phenotypic adaptation procedes the genotypic one. In the last case the genotypic variability cannot be considered as guiding factor of evolution. The plastic phenotypical characters arise when the population falls under the non - specific environmental deterioration which stimulates the selection favouring the wider reaction norm. When falling under new environmental conditions, or under the unusual extent of the environmental pressure, the individuals with the widest reaction norm will posesses of the best chances to survive. In general, the essential body of progressive evolution in plants and animals may be attributed to the increase of the flexibility in the phenotypic reactions. The essential proportions of ontogenetic and morphophysiological reactions, being designated by the uncertain term "adaptive modifications", as well as tne essential part of physiological and behavioral reactions are characterized by more or less prominent flexibility. In other words, the main part of characters which seem to determine the level of adaptation posess the wide reaction norm. When we are considering the correspondence between the organism and its environment, processes of this kind display more prominent evolutionary trend than processes based on the stable genetically determined characters.

The evolutionary environment is, first of all, the ecological niche, occupide by the population of the certain species in the certain biogeocoenosis. Therefore, the communities canalize the evolution of their populations. This is manifested in the most prominent way when we are considering the coadaptive complexes - the groups of species with the most tight ecological linkages in limits of biogeocoenosis At the same time, the community as a whole changes in coherence with the evolution of its populations. In fact, although the community delimits the direction of evolution of these population, these limitations are not strict: the adaptation to the conditions of a given ecosystem may not contradict to the adaptation of the other populations of the same species which belong to other ecosystems. Contradictions of this kind seem to lead to the intraspecific differentiation and. finally, to the formation of species thus leading to the evolution of the ecosystems itself. The control of the composition of the population by the community may be brought about in two opposite ways: in the pres'ervence of the existing adaptations (the stabilizing selection), and in the formation of the new ones (the directional selection). As far as every sertain population, being controlled by the ecosystem (as regulator) at the same time appears to be a part of a regulatory system for other populations of the same community, the evolution of ecosystems is based on the coadaptive evolution of their components. The species, being considered as a system of interconnected populations, is included into several communities which may be fairly different in their composition. The adaptation of a given population in frames of one or another ecosystem (dependent on its everybiontness) effects all the other populations of the same species. As a result, the otheres species of the given ecosystem have to adapt to the changes which occur in the former species and thus constitute a part of the regulatory system of their evolution. For example the specialization of the species is hindered by the fact that they are involved into different communities. At the same time, as far as every species is adapted to the certain environmental range of conditions, the communities of the species (in spite of the fact that their structure is reproducible under given abiotic conditions) are always formed from the existing species, which replace one another, the course of this replacement being dependent on the biotopic peculiarities and the succession stage. Each population of the ecosystem develops under the influence of the complexion of environmental conditions. The adaptive requirements of this complex are full of contradictions thus preventing the complete adaptation to them. This is equivalent to the maintaining of the selection favouring the existing trends of adaptation These selective vectors are differently directed to counterbalance each other This leads to the stabilization of the population which looses the capacity to be subject to any directional change. In spite of the environmental fluctuations, this provides a basis for the stabilizing selection, especialy for its canalising subform.

Fluctuations in the ecosystem result in the alteration of the relative strength of different selective vectors. In the restricted environmental conditions the strengthening of a given vector automatically leads to the strengthening of some other selective vector in the opposite direction. Provided that we are considering a character with a wide reaction norm, this stimulates the selection favouring its farther expansion. Provided that we are considering characters possesing the strick genetic determination, this lead to selection, favoring heterosigous genotypes (Dobzhansky 1970), i. e. the increasing of the genetic variability.

The directional selection arises from the disbalance of the actualy existing selective vectors or as a result of the appearence of the new one caused by the change of the environmental conditions. The adaptation of the pests to pesticides is an example. Thus, the counterbalance of the selective requirements which arises at the ecosystemal level of life organization leads to the evolutionary stability of populations. At the same time, this makes them evolutionary flexible, this flexibility being itself an adaptation to the fluctuating environmental conditions.

The consideration of the directionality of evolution at the level of macroevolution, when we are taking into account the change on the scale of the object (from population to individual), as well as the change on the scale of the time (the "geological" time), alters the notion of the agencies which determine the direction of phylogenesis. The individual variability is out of account. The individual organization, instead of offering a mechanism for the rapid directional adaptations arising from the phenotypic flexibility, imposes constraints on the number of potentially possible ways of evolution. The flexibility of characters is determined not by the expansion of their reaction norm, but rather by the exetnt of their polyfunctionality. The ways of the phylogenetic change of characters in relation to their function are extremly variable. Coordination provide a mechanism which delimits the responce to the selection favouring any of the functions of the given functional system. This is a reason why the possibility of changes in the direction of phylogenesis is restricted by the coordinations within the organism (or by the degree of heterobatmia giving the mesure of the lack of coordination).

In the sophisticated complexion of coordinations the secondary changes occuring in the several coordinated units may become the primary one with respect to some other chains of coordinations thus leading to alterations directed frome the center to the periphery of these chains. This is the reason why the coordinations lead not only to the limitation of the number oof potentialy possible ways of phylogenesis. When changing the organization, they switch a reaction of the organism to the environmental changes thus leading to the increase of their evolutionary plasticity. Another way to avoid the lost of the evolutionary flexibility concerned with the increase in the degree of coordination between the parts of an organism is offered by means of recombination and (or) transposition of the functional blocks (Ugolev 1985). The evolution on the level of recombination of functional blocks seemed to play an important role in the progress of the organization. Finally, the coordinations themselves may be ruptured or rebuilded in the course of the progressive evolution resulting in the release of some components of the coordination chains along with the fixation of other components thus leading to the change of their potencies to the further rearrangements.

Only in the relatively rare cases the coordinations do impose constraints which prevent a given evolutionary trend, in spite of the existence of the corresponding selective vector. This happens when the rupture in the coordination chains leads to the lost of fitness. But in the more usual situation, the preservance of the existing direction of the evolution in spite of environmental fluctuations and decrease of evolutionary flexibility is due to specialization which, at the level of the organism, is expressed in the drop of polyfunctionality of the organs, which are immediately connected with the adaptation to the environment. This tendency to conserve the existing trend should be considered as the most prominent manifestation of the directional nature of the evolution.

The constraints imposed on the direction of phylogenesis by the organization which is inherent to the individuals of a given taxon are to be realized in the concrete environmental conditions, i. e. inside the adaptive zone of this taxon. The limits of the adaptive zone usually become more rigid in the process of the phylogenesis. This is due to the splitting of the ancestral adaptive zone into the daughter ones in the process of the divergence of this taxon or due to the formation of the coadaptive complexes. In both cases this leads to the strengthening of the competition at the boundaries between the daughter subzones in the process of their coherent evolution. Another reason for the process of their coherent evolution. Another reason for the fixation of bondaries between adaptive zones is the loss of heterobatmia in the course of the phylogenesis of the taxon. The interdependence between the organization of taxa inhabiting the neighboring zones produces the parallelisms which are very attractive for the investigators of phylodenesis.

There is a range of paleontological and neontological evidence of the in- same adaptive zone. This puts the problem of polyphyly and monophyly as a dependent introduction of the similar and hardly distinguishable forms into the taxonomical problem, not the evolutionary one.

The organizational prerequisits (preadaptations) which allow for the expansion into the new adaptive zones arise frome the early and rapid specialization which has ocured in the abberant adaptive zones, aspecially in the asonal associations. The evolutionary flexibility of these forms which have specialized in a marginal zones is coincident with their heterobatmia. Expansion to the new adaptive zone may be realized either by the shift from the ancestral taxon zone lo the new one, or by its widening, i. e. involving of the supplementary environment, the lost corresponding to the aromorphic evolution. The complication of the environmental conditions leads to the complication and the progress of the organization. The formation of aromorphosis is a rather slow process. The rates of this process are limited by the formation of the coordination between characters which provide the adaptation both in the previous and in the newly acquired parts of the adaptive zone, and characters which provide the adaptation only to the one of these parts.

The expansion to the new adaptive zone leads to the adaptive radiation of the engaged taxon, with the range of a fan sweep corresponding to the acquired area. Adaptive radiation leads to the splitting of the adaptive zone into subzones and thereby to the substitution of the aromorphosis by the allomorphosis. In the course of this process some taxa are displaced to the abberant (marginal) adaptive zones, the adaptation to which initiating the new aromorphosis.

Allomorphic evolution according with the zone change or with the adaptation to the zone which has been already occupied may take place for an unlimited time period. However, the continued divergence leads to the further splitting of the adaptive zone and thereby, to the specialization of at least a part of the taxa occupying it. In this case, specialization arises from the loss of the heterobatmia. Therefore, if the retarded specialization is accompanied by the decrease in the degree of polyfunctionality of the organs along with the "decreas of heterobatmia, this may result in the extinction of such a taxon. However, if the environment remains unchanged, these particular taxa (highly adapted in the specific environmental conditions) tend to persist. On the contrary, the early specialization may give rise to the new aromorphosis. This means that in the course of phylogenesis the number of potential directions for the evolution of the taxon will increase. While the aromorphosis is always succeeded by the allomorphosis, the allomorphosis in not necessary succeeded by specialization. Specialization, appears to be extremely diverse in itself, leading to the three types of effects: to the new aromorphosis, persistance, or extinction. This evolutionary rule points out that the directional, sometimes strictly canalized process of evolution, is nevertheless undetermined, being neither teleological, nor final.