Vol 52, No 14 (2018)

Comparative genomics helps to link characteristics of the genome and evolutionary trajectories by revealing the genomic correlates of morphological complexity and differences in the body plans of multicellular animals. Comparison of the organization of Hox clusters and expression of Hox genes with organismal morphology allows the emergence of macroevolutionary innovations as changes in morphogenesis and body plan of Bilateria, depending on the pattern of Hox code to be traced. We examine a correlation node that includes various types of organization of clustered (initially) Hox genes, early embryogenesis type, cellular developmental resources, thereby determining alternative evolutionary trajectories of various Bilateria taxa. Biological diversity inevitably manifests itself at all levels of organization and all stages of the evolution of the animal world, and therefore the reduction of the evolutionary strategies of Bilateria, and, moreover, all Metazoa, to a few simplified versions is impossible.

Architectonics is the study of the division of the animal body into modular structures that are to some extent autonomous in their ontogeny and phylogeny. Thereby it allows key points in the ontogeny of many fossil taxa to be identified. Studying the symmetry of the mutual arrangement of the modular structures of the organism and its evolution, together with the analysis of architectonics, promorphology helps to clarify the evolution of ontogeny in real geological time and thereby brings together paleontology and developmental biology. The application of this approach to echinoderms enables the presence of a torsion process in the ontogeny of all Pelmatozoa and Soluta (among Carpozoa), and the absence of this process in Stylophora, to be demonstrated. The analysis of architectonics and promorphology of Paleozoic tetracorals (Rugosa) revealed the correlation of the oral-aboral and dorsal-ventral axes of their larvae with the oral-aboral and directive axes of the polyp developing from them. This shows that the bilateral symmetry of Anthozoa and possibly of all Cnidaria preceded their radial symmetry.

In previous papers, the author has shown that the polyhedral structures of fullerene type are widespread in the living and mineral worlds. They are most clearly manifested in the capsids of icosahedral viruses, the geometry of which has been well studied. This article demonstrates that the nomenclature, classification, and potential transformations of these polyhedral structures can be succinctly described by means of matrix algebra.

Bothrophyllum conicum displays three known types of regeneration. The damaged zone is rebuilt during epimorphosis, as observed in cases of healing. Compensatory regeneration, typical for many groups of corals, is expressed in the restoration of the diameter of corallites and the typical arrangement of septa after reduction of diameter and “rejuvenation” of the arrangement of septa. Morphallaxis is the most morphogenetically complex process, in which the development of one or several buds on the maternal corallite from the residues of tissues of a damaged corallite is possible. The reorganization of the damaged tissue during morphallaxis is similar to asexual reproduction in the arrangement of newly formed septa, which are positioned like buds relative to the skeletal elements of the maternal corallite. If the maternal corallite dies, forming multiple buds, the space between the buds continues to develop and grow, forming a kind of connective tissue around the bud corallites, with a large number of skeletal elements. Probably, this tissue of the maternal organism between the buds is a source of material for the newly formed buds, similar to the coenosarc in colonial corals. The location of the plane of symmetry passing through the main and opposite septum of the buds usually coincides with the direction of the most pronounced septum of the maternal corallite that underlies the bud. Sometimes, with no dominant septa at the base of the buds, the plane of symmetry is perpendicular to the maternal septa.

The diversity of the brachiopod order Spiriferida at the Devonian–Carboniferous boundary possibly formed due to the changes in the sedimentation that took place during this period and influenced the composition and hardness of the seafloor substrates and bottom-water hydrodynamics in the marine basins. These characteristics are considered among the main factors, both stimulating and restricting, that determined the composition and ethological trophic type of the main spiriferide taxa at this stage.

The history of Paleozoic ammonoids can be subdivided into two large intervals: Devonian and Carboniferous–Permian. There were two major evolutionary pathways: changes in the external shell morphology and changes in the suture, a character observed only in cephalopods. Almost all major shell types and ornamentation appeared at early stages of the evolution of the subclass Ammonoidea (archaic diversity). The suture in ancient taxa in this group was represented by virtually all known types, except for the complexly dissected suture lines of the “Mesozoic type” that appeared only at the end of the Paleozoic. During the time of the subclass’s existence, Devonian morphotypes recurrently appeared in different orders. The senile diversity was associated with the diversification of exotic taxa at the end of the Ammonoidea evolution.

The frequencies of five abnormal variants of juveniles in populations of the moor frog Rana arvalis in urbanization gradient are analyzed based on 39-year-long monitoring. The data on the limits of occurrences of this deviations in natural conditions are obtained. An increase in the frequency of features under study with the growth of concentration of certain ions, general mineralization, and pH is recorded. Notwithstanding fragmentation of environment and insulation of continuous geographical range, parallelism of the trends in morphological changes in particular isolates is shown. At the same time, the distribution of relatively rare anomalies can be limited by the presence of natural physical barriers.

The specifics of modular organisms led to a diversity of life cycles, and various forms of embryonization have significantly increased it. The reduction of one or two generations contributed to a significant transformation of the cycles and organization of bionts. The main modes of evolution of the life cycles of modular organisms, coupled with the processes of embryonization of ontogeny, are considered and their role in different systematic groups is estimated.