Zhurnal obshchei biologii最新文献

Investigations were carried out at two stations of Ornithological Unit, IBPN FEB RAS, located in Nizhnekolymsk District, Yakutia, starting from May 15-20 in 1984, 1985, 1987, 1988, and 1990; at the northern coast of Pukhovoy Bay, Southern Island of Novaya Zemlya starting from June 1 in 1994; at Cape Beliy Nos, the Yugorsky Peninsula, starting from June 1 in 1995-1997. Classic associations are detected in interspecies flocks of sandpipers between the following species: the Pacific golden plover and the curlew sandpiper, the pectoral sandpiper and the long-billed dowitcher, the pectoral sandpiper and the dunlin, the grey plover and the dunlin. However, total amount of birds that form associations is not large. In species of group "A" (the grey plover, the Pacific golden plover, the pectoral sandpiper), no difference has been observed in migratory birds behavior within inter- or conspecific flocks. Species of group "B" (the dunlin, the curlew sandpiper, the long-billed dowitcher), on the contrary, change their behavior sharply depending on whether they belong to an association or not. Species of group "A" do not get any advantages when forming an association. Unlike them, species of group "B" profit from associating: a part of time spent in foraging substantially increases; more time is spent on rest and less time is spent on reconnaissance and vigilance (readiness for actions); safety of birds is enhanced. On the other hand, in species of group "B" there are also disadvantages related with associating: i.e., interspecies competition for food; foraging in suboptimal habitats which, in turn, may lead to notable increase of time spent by birds in foraging. An assumption is put forward that in species of group "B" advantages and limitations of associating cancel each other to a certain extent, and this explains rather small number of birds forming associations.

Although many recently published original papers and reviews deal with plant matter decomposition rates and their controls, we are still very short in understanding of these processes in boreal and high latiude plant communities, especially in permafrost areas of our planet. First and foremost, this is holds true for winter period. Here, we present the results of 2-year field observations in south taiga and south shrub tundra ecosystems in European Russia. We pioneered in simultaneous application of two independent methods: classic mass loss estimation by litter-bag technique, and direct measurement of CO2 emission (respiration) of the same litter bags with different types of dead plant matter. Such an approach let us to reconstruct intra-seasonal dynamics of decomposition rates of the main tundra litter fractions with high temporal resolution, to estimate the partial role of different seasons and defragmentation in the process of plant matter decomposition, and to determine its factors under different temporal scale.

Contemporary state of the competitive intransitivity hypothesis is considered. Intransitive competition among species occurs when, for example, species A outcompetes species B, B outcompetes C, and C out-competes A (sometimes written as A > B > C > A). In the first part of the article, a summary of the studies of competitive intransitivity is given. Examples of really existing intransitive loops are discussed, as well as simulation models that provide a theoretical explanation for these processes. Pro hac vice, sufficient potential diversity of community, species interactions carried out in relatively stable limited space that can be reclaimed, and a penalty for the acquisition of competitive ability are prerequisite. In the second part, the hypothesis of competitive intransitivity is compared with neutral theory and niche theory. The results are believed to make some generalizations possible which could stimulate deeper understanding of the species coexistence phenomenon.

During the summer season of 2010, abundance and productivity of picocyanobacteria in Gorky and Cheboksary Reservoirs have being examined. It is found out that in the eutrophic reservoirs of the Middle Volga abundance and biomass of picocyanobacteria, averaged over the water column, varied within the range of (34-322) x 10(3) cells/ml and 38-455 mg/m3 respectively. In more productive Cheboksary Reservoir, the contribution of picocyanobacteria in total biomass and production of phytoplankton (4.7 ± 0.7 and 8.3 ± 1.3% respectively) was lower than in less productive Gorky Reservoir (10.6 ± 2.1 and 19.2 ± 3.0% respectively). In both reservoirs, high level of picocyanobacteria infection by viruses was detected. The frequency of visible infected cells and virus-induced mortality of picocyanobacteria in Cheboksary Reservoir were substantially higher (3.2 ± 0.4% of total abundance and 21.8 ± 2.9% of daily production) than in Gorky Reservoir (1.7 ± 0.2% of total abundance and 11.0 ± 1.7% of daily production). The results obtained indicate that in eutrophic reservoirs during summer bloom of large cyanobacteria their abundance is regulated to a great extent by viruses.

The formalism allowing to describe animals' behavior is based on the model of informational interactions between an animal and its environment. The model may be represented as an assemblage consisting of two blocks. The first block, which corresponds to the perception system, is a probabilistic operator: it selects an object of certain class out of many objects randomly encountered by an animal while it moves around. The selected object keeps its actuality as an input symbol for the second block of the assemblage during one or several cycles of the block operation. The second block, being afinite structural probabilistic automaton, generates output reactions to the input symbol. The structural automaton, which consists of elementary automata, produces a sequence of output reactions in course of interactions with the selected object: After exhaustion of the previous input actuality, the assemblage moves to the next cycle. At that, the probabilistic operator comes back to the receptive state and produces next output. Automaton "inputs" correspond to objects of certain classes, selectively perceived by an animal; "outputs" correspond to a sequence of elementary motor reactions. Based on data on snow tracking of pine marten foraging activity, there have been composed: the assemblage input and output alphabets, a conjugation matrix of input signals and internal states of the first elementary automaton that is contained in the second block structure, and transition probability matrices for the states of the second block elementary automata, which are defined for a class of environmental objects when foraging activity occurs. The proposed formalism makes it possible to convert field data on tracking into the unified form, detect key circumstances of animals' behavioral activity, and analyze this natural phenomenon in detail.

Considered are trends in the development of two basic parts of phytosociology--syntaxonomy (vegetation classification) and vegetation dynamics. At the end of XX century, the consolidation of researches in the field of syntaxonomy has taken place on the base of Braun-Blanquet approach, as well as the development of syntaxonomy due to studies of vegetation in new regions, and adoption of information technologies. In Russia, Braun-Blanquet approach has being implemented only in 1980s, because before that its spread was impeded by political climate in the country. Presently, syntaxonomy of vegetation in Russia includes 80 classes, 169 orders, and 377 alliances, at that considerable part of them are new for the science. In the theory of vegetation dynamics, the paradigm shift has occurred in XX century--from organicism to the concept of continuum. From the beginning of XXI century, the interest in general theory of successions has being receded and, instead, particular patterns of successions of different type have being revealed.

A homogeneous Markov chain of three aggregated states "pond--swamp--wood" is proposed as a model of cyclic zoogenic successions caused by beaver (Castor fiber L.) life activity in a forest biogeocoenosis. To calibrate the chain transition matrix, the data have appeared sufficient that were gained from field studies undertaken in "Bryanskii Les" Reserve in the years of 2002-2008. Major outcomes of the calibrated model ensue from the formulae of finite homogeneous Markov chain theory: the stationary probability distribution of states, thematrix (T) of mean first passage times, and the mean durations (M(j)) of succession stages. The former illustrates the distribution of relative areas under succession stages if the current trends and transition rates of succession are conserved in the long-term--it has appeared close to the observed distribution. Matrix T provides for quantitative characteristics of the cyclic process, specifying the ranges the experts proposed for the duration of stages in the conceptual scheme of succession. The calculated values of M(j) detect potential discrepancies between empirical data, the expert knowledge that summarizes the data, and the postulates accepted in the mathematical model. The calculated M2 value falls outside the expert range, which gives a reason to doubt the validity of expert estimation proposed, the aggregation mode chosen for chain states, or/and the accuracy-of data available, i.e., to draw certain "lessons" from partially successful calibration. Refusal to postulate the time homogeneity or the Markov property of the chain is also discussed among possible ways to improve the model.

Currently at least two independent systems of magnetoreception are believed to exist in birds, based on different biophysical principles, located in different parts of their bodies, and having different innervation. One magnetoreceptory system is located in the retina and may be based on photo-induced biradical chemical reactions on the basis of cryptochrome. Information from these receptors is processed in a specialized part of visual Wulst, the so-called Cluster N. There are good reasons to believe that this visual magnetoreceptor processes compass magnetic information which is necessary for migratory orientation. The second magnetoreceptory system is probably iron-based (biogenic magnetite), is located somewhere in the upper beak (its exact location and ultrastructure of receptors remain unknown), and is innervated by the ophthalmic branch of trigeminal nerve. It cannot be ruled out that this system participates in spatial representation and helps forming either a kind of map or more primitive signposts, based on regular spatial variation of the geomagnetic field. The magnetic map probably governs navigation of migrating birds across hundreds and thousands of kilometers. Apart from these two systems whose existence may be considered to be convincingly shown (even if their details are not yet fully clear), there are data on the existence of magnetoreceptors based on the vestibular system. It cannot be ruled out that iron-based magnetoreception takes place in lagena (a structure homologous to cochlea of marsupials and eutherians), and the information perceived is processes in vestibular nuclei. The very existence of this magnetoreception system needs verification, and its function remains completely open.

High variability of cells size is used selectively for reproduction of working bees and drones. A decrease in both distance between cells and cells size themselves causes similar effects to body mass and morphometric traits of developing individuals. Adaptation of honey bees to living in shelters has led to their becoming tolerant to hypoxia. Improvement of ethological and physiological mechanisms of thermal regulation is associated with limitation of ecological valence and acquiring of stenothermic features by breed. Optimal thermal conditions for breed are limited by the interval 33-34.5 degrees C. Deviations of temperature by 3-4 degrees C beyond this range have minimum lethal effect at embryonic stage of development and medium effect at the stage of pre-pupa and pupa. Developing at the low bound of the vital range leads to increasing, while developing at the upper bound--to decreasing of body mass, mandibular and hypopharyngeal glands, as well as other organs, which, later, affects the variability of these traits during the adult stage of development. Eliminative and teratogenic efficiency of ecological factors that affect a breed is most often manifested in underdevelopment of wings. However, their size (in case of wing laminas formation). is characterized by relatively low variability and size-dependent asymmetry. Asymmetry variability of wings and other pair organs is expressed through realignment of size excess from right- to left-side one with respect to their increase. Selective elimination by those traits whose emerging probability increases as developmental conditions deviate from the optimal ones promotes restrictions on individual variability. Physiological mechanisms that facilitate adaptability enhancement under conditions of increasing anthropogenic contamination of eivironment and trophic substrates consumed by honey bees, arrear to be toxicants accumulation in rectum and crops' ability to absorb contaminants from nectar in course of its processing to honey.

Relying on own data (267 quantitative samples in total), factors of rheophilous zoobenthos formation in East Fennoscandia have been studied with use of detrended correspondence analysis. In the period from 2005 to 2011, in August, samples were taken from 90 stony rapids belonging to 39 streams. On East Fennoscandia territory, which extends over 1000 kilometers in south-north direction, climatic factor plays an important role in formation of macrozoobenthos in streams. With regard to both species composition and total abundance, the poorest benthic communities are found in tundra rivers in the northern part of the region. In limnetic-riverine systems of south Karelia, on the contrary, rheophilous macrozoobenthos is characterized by great number of species and high biomass. However, the structure of benthic communities is markedly influenced, beside the climate, by flowing lakes and settlements located in the catchment area. Under their influence, the species richness of zoobenthos in streams decreases while the biomass increases. Under the conditions of low trophic status that are indicative of northern water bodies, these sources of additional organic matter and biogenic elements improve feeding conditions for macrozoobenthic organisms which, in its turn, leads to biomass and production growth.