Zhurnal obshchei biologii最新文献

Higher plants show a wide range of leaf lifespan (LL) variability. LL is calculated as a sum of functional LL(f) (corresponding to the time of active photosynthesis and CO2 accumulation in the leaf) and nonfunctional LL(n) (the time of photosynthetic activity absence). For evergreen species of boreal zones, LL(n) corresponds to the period of winter rest. Photosynthetic potential of leaf (PPL), interpreted as the maximum possible amount of CO2 that can be fixed during its life, can be estimated on the basis of maximum photosynthesis rate (P(a)) dynamics during LL(f); the maximum (P(a max)) being achieved in mature leaf. Photosynthetic potential depends on LL(f) more strongly than on P(a max). The PPL/LL(f) ratio is indicative of the rate of PPL realization over leaf lifespan. As LL(f) shows strong positive correlation with LL, the latter parameter can also characterize the rate of PPL realization. Long LL(f) in evergreen species provides higher PPL, which is advantageous by comparison with deciduous ones. In evergreen species, the PPL itself is realized slower than in deciduous ones. The increase in LL(f) and LL is accompanied by the increase in leaf constructional cost (LCC(a)) as well as the decrease in photosynthesis rate. At that, photosynthesis rate per unit of dry weight (P(m)) decreases much faster than that per unit of leaf area (P(a)). Apparently, when considering dry leaf weight, the apoplast share seems to be much higher in long-living leaves of evergreen species than in short-living leaves of deciduous species. The leaf payback (LP) may be stabilized by unidirectional shifts in PPL and LCC(a). Species with short/long LL(f) and high/low PPL realization rate are typical for early/late succession stages and for habitats with the environmental conditions favorable/adverse for photosynthesis and growth. If the conditions for photosynthesis and growth are favorable, high PPL realization rate provides advantage in competition. The PPL realization rate is coupled with the rate of leaf senescence.

L.G. Ramensky (1884-1953) was an outstanding Soviet geobotanist of the first part of XX century. Considered is his theoretical legacy and its contribution to modern vegetation science. L.G. Ramensky formulated the principle of vegetation continuum based on which the modern paradigm of vegetation science has been put into shape. The scientist made a contribution to the development of such important theoretical conceptions as types of plant strategy, coenosis and coenobiosis (coexistence of species), patterns of interannual variability in plant communities, ecological successions. The unique ecological scales were established by L.G. Ramensky that characterize the distribution of 1400 species over the gradients of soil moistening, richness, and salinization as well as moistening variability, pastoral digression, and alluvial intensity. He came out against mechanistic notions by V.N. Sukachev on a biogeocoenosis structure. The scientist did not offer his own method of plant communities classification but his well-reasoned criticism of dominant classification played a great role in adoption of floristical classification principles (Braun-Blanquet approach) by phytocenology in our country.

Some physiological parameters that determine quality of male sperm (its concentration, spermatozoa morphology) and testicle size vary in integrity, i.e. the bigger are testicles the higher is sperm quality. Therefore, the estimate of testicles relative mass is often used as a characteristic of sperm competitive ability when comparing phylogenetically close mammal species. In house mice belonging to the superspecies complex Mus musculus s.l., testicles relative mass is greater in exoanthropic species than in synanthropic ones. It is shown in our study that this pattern is apparent also at the intraspecies level since testicles mass index, sperm concentration, and percentage of morphologically normal spermatozoa in subspecies Mus musculus wagneri, which is facultatively synanthropic, are higher compared with synanthropic subspecies M m. musculus. An analysis of sexual behavior of the three forms (namely, exoanthropic species M. spicilegus and two subspecies mentioned above) indicates that in M. spicilegus both sexual behavior efficiency and ejaculation rate during coupling were higher as compared with other two subspecies. Based on the analysis of life pattern, reproduction systems, and group spatial-ethological structure, the hypotheses are formulated that explain the maintenance of selection directed to increase of sperm competitive ability in exoanthropic house mice species.

Understanding mechanisms that underlie species' distribution and abundance is one of the key problems in population ecology. Inorder to tackle this problem, it is important to assess the relative strength of the effects of food and predator (consumer) on a focal population. In this study we have analysed advantages and disadvantages of the basic methods that are used to quantify the relative strength of the two types of effects. These methods can be divided into two groups. In the first group we put the search for examples that are consistent with a proposed hypothesis, assessment of correlations of abundance on adjacent trophic levels and biomanipulations. Common for these methods is that they assume the existence of only one type of effects--either bottom-up or top-down. Methods of the second group assume simultaneous presence of both types of effects and are aimed at quantifying their relative strength. In this group we put factorial design experiments and population-dynamics approach (analysis of population growth, death and birth rates). It is shown that due to the constraints of each of the methods of the second group none of them can be considered universal. However, their joint application can be a promising approach to the assessment of the mechanisms that drive population abundance variability both in experimental and field studies.

The present approach to the use of subspecies category in zoological systematics is an integrative one. It counts as obligatory to confirm the validity of subspecies, defined by morphological data, with genetic criteria. This allows marking out those subspecies that really exist as separate monophyletic population groups. As a result, the system would be cleared of many 'phantom' taxa established in course of non-critical use of the subspecies concept. However, detailed analyses of intra-species variability by methods of molecular taxonomy in many cases reveal a quite complicated divergence pattern which cannot be adequately described in terms of the classic scheme of 'species and its subspecies'. Keeping in mind the irregularity of intra-species divergence rate when dealing with molecular and morphological traits, it is proposed to use an extended system of subspecies taxa when describing 'extra complicated' situations. In addition to a 'subspecies' such categories as 'allospecies', 'morphotype', 'morphospecies' may be used for which operational definitions are suggested. As an example, the micro-systematics of the great pond snails (the complex Lymnaea stagnalis s. lato) from Palaearctic region is examined. The provisional system of this group, developed by the author, is based on morphological and phylogeographical data. Applying the series of subspecies categories of different level allows reflecting with maximal completeness the intra-species variability of great pond snails and, to some extent, the process of their genetic divergence and geographic range forming. The second part of the article deals with modern approaches to subspecies category usage in zoological systematics as well as the problems of so called micro-systematics, i.e., systematics operating at the lowest level of categories such as ones of subspecies and infra-subspecies rank (Mayr, 1982).

The refined Markov model of cyclic zoogenic successions caused by beaver (Castor fiber L.) life activity represents a discrete chain of the following six states: flooded forest, swamped forest, pond, grassy swamp, shrubby swamp, and wet forest, which correspond to certain stages of succession. Those stages are defined, and a conceptual scheme of probable transitions between them for one time step is constructed from the knowledge of beaver behaviour in small river floodplains of "Bryanskii Les" Reserve. We calibrated the corresponding matrix of transition probabilities according to the optimization principle: minimizing differences between the model outcome and reality; the model generates a distribution of relative areas corresponding to the stages of succession, that has to be compared to those gained from case studies in the Reserve during 2002-2006. The time step is chosen to equal 2 years, and the first-step data in the sum of differences are given various weights, w (between 0 and 1). The value of w = 0.2 is selected due to its optimality and for some additional reasons. By the formulae of finite homogeneous Markov chain theory, we obtained the main results of the calibrated model, namely, a steady-state distribution of stage areas, indexes of cyclicity, and the mean durations (M(j)) of succession stages. The results of calibration give an objective quantitative nature to the expert knowledge of the course of succession and get a proper interpretation. The 2010 data, which are not involved in the calibration procedure, enabled assessing the quality of prediction by the homogeneous model in short-term (from the 2006 situation): the error of model area distribution relative to the distribution observed in 2010 falls into the range of 9-17%, the best prognosis being given by the least optimal matrices (rejected values of w). This indicates a formally heterogeneous nature of succession processes in time. Thus, the refined version of the homogeneous Markov chain has not eliminated all the contradictions between the model results and expert knowledge, which suggests a further model development towards a "logically inhomogeneous" version or/and refusal to postulate the Markov property in the conceptual scheme of succession.

Angiosperm gynoecium consists of elementary units, called carpels. These can be free (apocarpy) or united (coenocarpy, or syncarpy in a wide sense). One of the most complicate problems of evolutionary morphology of angiosperms is distinguishing monomerous and pseudomonomerous gynoecia. The former are assumed to be derived by reduction of carpel number in apocarpous gynoecia, the latter by reduction of gynoecia with united carpels. Pseudomonomerous gynoecia have one fertile carpel and more or less prominent traces of sterile carpel(s). In extreme cases of reduction, pseudomonomerous gynoecia are very similar to monomerous, even though the two types have completely different evolutionary histories. G.B. Kedrov (1969) proposed a new approach to resolving the issue. Using the fact of absence of polymerous free-carpellate gynoecia with inferior ovaries, he suggested that there is a constraint against epigyny in plants with free carpels. Therefore, in taxa with disputable morphological interpretations, the gynoecium should be treated as pseudomonomerous (and not monomerous) if the ovary is inferior. A critical review of the concept of G.B. Kedrov showed that his ideas would suggest re-interpretation of widely accepted views on gynoecium morphology in several key families of basal angiosperms. An alternative view is proposed, that for most important types of epigyny in angiosperms, a "constraint" for a combination of inferior ovary and apocarpy is due to definition of the term "apocarpy" only. There is no biological sense in this "constraint". Existence of two other morphogenetic constraints is proposed: (1) against development of a typical inferior ovary in monomerous gynoecia with conduplicate carpel and (2) against a radial (sectorial) fusion of individual carpels with stamens or perianth members without fusion of these groups into an entire structure. Possible biological nature of these constraints is discussed.

In summer of 2013, field studies of CO2-exchange in tundra ecosystems of Vaygach Island have been conducted using the chamber method. The models are developed that establish relationships between CO2 fluxes and key ecological factors such as temperature, photosynthetic active radiation, leaf mass of vascular plants, and depth of thawing. According to the model estimates, in 2013 vegetation season tundra ecosystems of Vaygach Island have been appearing to be a CO2 source to the atmosphere (31.9 ± 17.1 g C m(-2) season(-1)) with gross primary production equal to 136.6 ± 18.9 g C m(-2) season(-1) and ecosystem respiration of 168.5 ± ± 18.4 g C m(-2) season(-1). Emission of CO2 from the soil surface (soil respiration) has been equal, on the average, to 67.3% of the ecosystem respiration. The reason behind carbon losses by tundra ecosystems seems to be unusually warm and dry weather conditions in 2013 summer. The air temperature during summer months has been twice as high as the climatic norm for 1961-1990. Last decades, researches in the circumpolar Arctic revealed a growing trend to the carbon sink from the atmosphere to tundra ecosystems. This trend can be interrupted by unusually warm weather situations becoming more frequent and of larger scale.

Studying mesenchymal stromal cells (MSC) is a very topical problem. Numerous experiments in vitro promoted understanding of MSC biology to a great extent. However, many aspects of their behavior in vivo still remain unclear. This review deals with MSC localization and functioning in an organism. MSC are present in various tissues, changing their numbers and traits during ontogenesis. Pericytes, or adventitial cells, can be considered as possible equivalents of MSC in vivo. Self-maintenance, proliferation, and differentiation of MSC are controlled by their tissue microenvironment that includes surrounding cells, soluble molecules, and extracellular matrix. At early stages of ontogenesis, MSC, probably, migrate throughout an organism. The migration occur also through a mature organism when tissues happen to be damaged. MSC move pointedly to the damaged parts and render a reparative effect which is due, first of all, to paracrine production of bioactive molecules. Immunomodulatory properties of MSC also play their role in tissues regeneration. An important function of MSC consists in creation of hematopoietic microenvironment. They secrete humoral regulators of hemopoiesis such as cytokines and chemoattractants. In addition, they interact with hemopoietic cells via surface molecules. Possibly, MSC sustain the stable functioning of other tissues as well. Their unique features make them quite attractive for clinical use, although successful introduction of MSC into medical practice requires their further studying.