Ecologo-morphological changes of testacean shells in soil assemblages are considered. When assessing the level and evolutional significance of these changes (aramorphoses and idioadaptations), special importance is attached to the two-chamber structure of the shells and its buffer function. Different ways and principles of shell complication in aquatic and soil species are shown. In aquatic species, an additional chamber is located outside the main shell volume, in soil ones, inside. Ecomorphs of hydro- and geobionts are characterized. The latter demonstrate acrostome, plagiostome, and cryptostome plans of morphology according to symmetry type, form and size of shells, as well as the pseudostom structure and location. The most progressive bilateral symmetry in soil dwelling forms is related to both the irregular distribution of food sources and active movement ("crawling") of protozoans over soil particles. The role of preadaptations as morphological structures, beneficial in the course of soil colonization by fressh-water testaceans, is emphasized. While the main part of soil testaceans is represented by specific ecomorphs, certain species use an alternative adaptive strategy. They are morphologically simple eurybionts with high modification reserve and possibilities to adaptive radiation.
The altitudinal distribution of
Chernova N.M., Avilkina A.T.
A response of different collembolan speices to an increase of the population density was studied in laboratory cultures. The behavior of
The analysis of wing venation, tracheation, and folding patterns in selected representatives of over 120 beetle families revealed that all venation and folding patterns were based on a common structural plant. Despite being easily recognizable among wings of other pterygotes, this plan is derivable from the common, very primitive one. It is shared by all the endopterigotes and is especially close to the plan, characteristic of some megalopterans. Folding of the wing at rest is hypothesized to be one of the main determinatives in the evolution of the coleopteran wing venation. An original idea on how folding patterns evolved and affected some venation particulars in the beetle wing is put forth. The main stages of this process are briefly described, each corresponding to the origin of a particular structural plan of wing. Both the adelphagan (Adephaga + Myxophaga) and polyphagan plans, including corresponding folding types, seem to be derivable from those of Archostemata.
Possible pathways of historical development of Pulmonata shells, excretory apparatus and reproductive tract are considered. Actual materials and morphofunctional analysis show that the reduction of shell is a widespread process among historically young and morphologically progressive gastropods in general, and pulmonates in particular. Evolution of the reproductive system is also expressed to a greater extent in a reduction of various accessory organs. The reduction may be progressive (in chain of generations) as well as instantaneous, i.e. mutagenous. The general trend of the evolution in terrestrial pulmonates may be represented by the following order of phenomena: initial simplicity - morphological complication - physiological improvement - secondary morphological simplification at a higher developmental level.
The composition and structure of animal population in arable soils under winter wheat was studied in five soil types at the boundaries between the forest-steppe and steppe zones. The structure of the animal population in agrocenoses is shown to be determined by edaphic factros related to both the history of soil development and its recent biodynamics. The taxonomic composition of the macrofauna in different soil types on ecotones is formed on the basis of the zonal elements, partly retained in field agrocenoses. They serve as indicators for historical conditions of soil formation. In arable soils, the characteristic features of the structure of animal populations within their geographical ranges are preserved. In parcels of soils, isolated from their main areas, the characteristic structure of their animal population is destroyed and becomes similar to that in ambient soil types. Edaphic factors play a leading role in supporting the diversity of soil animal population in lands of agricultural use, even in perennial one-crop systems.
Two main variants of sociotomy (binary division and budding) in ants are related to the formation of new socia thorugh the destruction of definite initial social structures. The third variant of ant-hill sociotomy is fragmentation through the division of a family into its constituent columns. Each column preserves its own organization and integrity. The fragmentation is associated with a weakening of relationships between columns under the influence of interior and external factros. At the myrmecological reserve "Verkhnyaya Klyaz'ma" (Moscow oblast, Russia), the fate of 155 fragmented
Field hygropreferences are characterized for more than 70 collembolan species on the basis of the data on their abundance in coniferous forests located along the gradient of habitat humidity. The mesophilous, hygrophilous, and xeroresistant groups of collembolans were ditinguished. The mesophilous group includes about half of the species studied, hygrophilous and xeroresistant species represent the other half in equal shares. The most of hemi- and euedaphic species are mainly mesophilous, whereas the surface-dwelling ones are represented in all groups of field hygropreferences. Hygrophilous, especially neustonic sprintails are the most stenotopic. Xeroresistant species often show bimodal distribution with peaks of their abudance both in dry and wet habitats. Field hygropreferences of mesophilous species, expecially of xeroresistant ones, can vary from year to year. In the forests of Eastern Europe, the changes in biotope preferences of collembolans are consistent with zonal changes of habitats. In broad-leaved-coniferous forests, the number of species, which prefer wet sphagnum biotopes, is nearly two times as high as in the northern taiga. The changes in biotopic preferences are mainly characteristic of mesophilous species.
A brief historical survey of using testaceans in paleoecological studeis of lake-bog ecosystems is presented. Using the example of three peat columns from sphagnum bogs of Canada and Russia, the regularities of changes in the species composition and population structure of testacean communities (indicator species, dominant forms, ecological groups) in the Holocene are revealed.
Sharova I. Kh., Filippov B. Yu.
The development of widespread species of ground beetles (Carabidae) in the northern taiga was studied. The differences of life cycles between these carabid species in the northern taiga and in the zone of mixed forests were found. In the northern taiga, the vernal and atutumn peaks of the animal acitivty shift to summer periods. Adaptations of speceis with vernal reproduction type tothe environmental conditions of the North are expressed in the accelerated development due to the reduction of the reproductive period and synchronization of developing preimaginal stages of ontogenesis. The species with autumn type of reproduction tend to the biennial cycle. In thid case, the terms of reproduction are reduced and shift to summer periods. The adaptations described allow ground bettles with broad ranges to exist in conditions of the North and predominate by number in forest ecosystems.
Stebaev I.V., Kolpakov V.E.
The morpho-adaptive characteristics (ecomorphs, life forms) should be used in soil zoology for characterization of the structure of soil animal populations. A generalized system of ecomorphs in main types of insect larvae (apodous, oligopodous, and polypodous) is proposed that is constructred along gradients of two environmental characteristics - depth of soil profile and size of soil pores populated by invertebrates. The classification suggested was applied for zoological indication of soils in fluvial plains and altitudinal mountain belts along a gradient of increasing the climate continentality in Central Asia.
The morphological adaptations of terrestrial pulmonates (shell reduction, formation of shell streamline shape, and development of aperture armature as a conchological mechanism of shell management) to the locomotion in the lower layers of leaf litter are described. These adaptations are supposed to be accompanied by the formation of evolutionary cycles with a positive feedback development. The cycle includes the following positions: (1) effect of environmental factors on an organism; (2) initiation of adaptive response; (3) origination of evolutionary constrains as side results of the adaptive response, canalizing subsequent changes; (4) development of specialization. Elements of chance in macroevolutionary processes appear to be due to the selection of adaptive responses. The origination of a system with a positive feedback results in the formation of macroevolutionary trends.
Alfimov A.V., Berman D.I., Sher A.V.
July and January temperatures for certain periods of the Late Pleistocene were reconstructed by Mutual Climatic Range (MCR) analysis based on 18 modern steppe and tundra species of insects, recorded in various combinations in fossil faunas of the Kolyma Lowland. Two fossil assemblages come from the sediments dated about 45000 and 35000 years ago (Karginian Interstadial), two more - from sediments of the Sartanian Glaciation stage (16000-17000 and 13000-14000 years respectively). The reconstructed summer air temperatures appear higher than modern by 1.0^.5°C in Karginian times (12.0-15.5°C) and by 1.0-2.5° in the Sartanian (12.0-13.6°C). The reconstructed range of January air temperatures is shifted towards higher values as compared to the modern; it is shown, that the MCR method reconstructs winter temperatures less adequately than summer ones. At July average temperature of about 13-14°C (that now corresponds to sparse taiga forest), joint occurrence of steppe and tundra insect species on the Arctic lowlands in the Late Pleistocene was possible only under extremely continental climate. That climate must have provided sharper temperature gradients between soil and air than today, and high contrast in thermal and moisture conditions between different units of mesoand micro-scale topography. The results confirm that during the Pleistocene, peculiar conditions of climate and landscape may have existed (usually named tundra-steppe) that supported non-analogue plant and animal communities. Our results also allow us to define boundary air temperature conditions under which those communities could exist. Communities of tundra-steppe type evolved in glacier-free continental areas of northeastern Asia as early as in the beginning of the Pleistocene.
Mordkovich V.G., Andrievskii V.S., Berezina О.G., Marchenko I.I.
In soils of the northern taiga (63°N), 50 species of collembolans, 60 species of oribatids. and 30 species of gamasid mites were recorded. The ecological ordination of local microarthropod communities with respect to a standard set of habitats was performed. Five types of spatial distribution patterns applicable to a number of ecological groups of microarthropods were recognized. The soil types considered were distinguished according to abundance levels, species richness, taxonomic composition, and proportion of ecological groups. Soils with marginal features are characterized by the absence of the dominant ecological group, obligatory for native soil types. On sandy opencasts, appearing along building roads, microarthropods are pioneer communities. The restoration of ecosystems of the opencasts follows a scheme of afforestation. After 20 yeras, the microarthropod population in the opencasts does not differ from that in the intact forest soils, whereas to this time the vegetation is not restored.