集合种群空间混沌的模拟研究以及Allee效应、拥挤效应与捕食效应对空间模式的影响

集合种群的空间模式研究是当今生态学的核心问题之一。本研究利用常微分动力系统以及基于网格模型的元胞自动机模型对Allee效应、拥挤效应以及捕食作用集合种群的空间分布模式做了全面的模拟研究。Allee效应描述当种群水平低于某一阈值时会发生由生殖成功几率下降造成的种群负增长率,而拥挤效应是指当种群密度过高时引起的个体性为异常从而达到调节种群增长率的作用。文章组建了3个空间确定性模型：局部作用模型(CIM)、距离敏感模型(DSM)和集合种群捕食模型(MMP)。局部作用模型显示在一维生境中空斑块形成金字塔状,二维模型显示出明显的动态拟周期性以及由空间混沌所形成的异质性。距离敏感模型可导致由迁移个体中密度制约强度决定的集合种群大小复杂动态与种群密度的双峰分布。这些结果说明动态行为的复杂性,不仅可用于表征研究物种的特性,而且可以表明该物种的续存能力与灭绝风险。集合种群捕食模型是概率转换空间模型,利用该模型得出了依赖于模型参数和生境尺度的白组织种群概率空间分布模式。模拟的结果表明,系统的内在机制和这种白组织模式导致捕食者形成集团型不明显的“捕食小组”或“杀手小组”,并具有较高扩散力．但却包括侵占率低、灭绝率高的特点。而使猎物种群形成高集团性、高侵占率、低灭绝率、低扩散力的种群集团。这种特点又使捕食者种群在生境中处于中心地带,而使猎物种群形成在捕食者和生境边缘间的环状分布。这些结果还说明了尺度对于生态学的研究是至关重要的,不同的尺度将产生不同的系统模式。     

Demidov-Elagin-Fanchenko effect

It is shown how the plateau that has been revealed earlier in the nonlinear dependence of the experimentally studied electrical conductivity of a turbulent plasma on the electric field strength can be understood by taking into account the turbulent Joule heating of the plasma electrons. A new, experimentally possible physical pattern of the penetration of a quasistatic vortex electric field into a turbulent plasma is revealed that is attributed to the time dependence of the anomalous turbulent conductivity or, more generally, to the temporally nonlocal relationship between the current density and the electric field strength due to turbulent heating.     

Pyramid effect

The effect of a model pyramid of Egyptian type on plants, aqueous solutions, and solids was studied. It was found that a presowing holding of dry barley seeds in the pyramid stimulated the growth of this plant. On the contrary, "pyramid" water, when used in sowing, suppressed the early growth of plants. The pH of the water held in a pyramid changed compared to the norm. A threefold increase in the rate of decomposition of hydrogen peroxide was observed when an aqueous H2O2 solution was held in a pyramid. It was also found that the masses of both biological objects (seeds) and inorganic solids (quartz) changed in the intrapyramidal space.     

Root effect hemoglobins

The Root effect describes an extreme pH sensitivity expressed in the hemoglobins of certain fish, in which it plays a unique physiological role. This review describes our general understanding of the effect of protons on the oxygen binding properties of hemoglobin and the particular properties which characterize Root effect proteins. The development of our understanding of the molecular origins of this effect is outlined and the role played by our ever expanding knowledge of protein structure is highlighted. The present state of our knowledge is detailed.     

Radiation-induced bystander effect

Data concerning induction mechanisms, the objects and methods of investigation of a non-target radiobiological phenomenon bystander effect, its role in radiation-induced genomic instability and oncogenesis are summarized.     

The Root effect

Considering the presently available data it is clear that the Root effect represents an exaggerated alkaline Bohr effect which occurs in the absence of a normal acid Bohr effect and is associated with a loss of oxygen binding capacity at low pH. Undoubtedly at the molecular level the presence of a Ser residue at position F9(94) beta in these haemoglobin is of primary importance. No Root effect haemoglobin has yet been identified which lacks this substitution. On the other hand however many haemoglobins are known which possess this Ser residue and at the same time lack a Root effect. Other factors arising from interactions at other sites in the haemoglobin molecule are obviously sufficient to negate the otherwise stabilizing effect of this critical Ser residue. The loss of cooperativity of Root effect systems as the pH is lowered is readily explained as due to stabilization of the low affinity T state to such a degree that the switch to the high affinity R state is suppressed even in the fully liganded molecule. The observation of Hill coefficients of less than unity requires that within the T state chain heterogeneity exists such that the alpha and beta chain haems demonstrate significantly different affinities for ligand. The physiological role of Root effect haemoglobins is demonstrably not inevitably linked to the swim bladder but more probably arose from the need to oxygenate the poorly vascularized retina of many fishes.(ABSTRACT TRUNCATED AT 250 WORDS)     

The mother-in-law effect

Individuals often derive considerable evolutionary benefit from manipulating others. In the majority of cases, manipulation involves direct interactions between individuals. In the dung beetle, Onthophagus taurus, females mated with large males provide more resources to their offspring. Here, we demonstrate, however, that this may result in manipulation that extends across generations: the care that a mother provides to a developing son influences the parental effort of his mate (the mother's daughter-in-law (DIL)). Maternal care associated with constructing heavier brood masses has previously been shown substantially to influence offspring size, male mating success and female survival and fecundity in this species. The mother-in-law effect that we document here is, however, the ability to produce large sons from relatively lighter brood masses. Our results demonstrate not only that females are able to manipulate the parental effort of DILs that they do not directly encounter, but that provisioning relatively lighter brood masses may have evolutionary benefits that trade off against the considerable benefits of producing heavy brood masses.     

一年生植物群落内取样效应和互补效应的分离

利用人工建植的1年生植物群落对物种多样性．生产力关系及其潜在作用机理——取样效应和互补效应进行了研究。结果表明,不同多样性水平内群落生产力变化幅度较大,不同的物种组合对生产力水平也有较大的影响。植物种多样性与群落生产力之间呈二次函数关系。计算表明,所有混播群落均程度不同地存在多样性净效应,但不同多样性水平间及同一多样性水平内,净效应变化较大。物种多样性与生产力净效应间亦呈二次函数关系。多样性净效应与群落生产力水平呈显著正相关关系。多样性净效应的两个组成部分——取样效应和互补效应对多样性的变化有不同的反应：互补效应与物种多样性间呈单峰格局关系;而取样效应与多样性间呈显著的正相关关系。取样效应和互补效应均随着群落生产力的提高而显著增强。结果还表明,除物种多样性外,物种的组成（或物种的特性）对群落生产力、多样性净效应及其分解成分——取样效应和互补效应均有显著影响。据此,可以认为在短期多样性实验中,取样效应和互补效应均对多样性．生产力正相互关系产生作用,但取样效应的强度要大于互补效应。     

Microwave effect on diffusion: a possible mechanism for non-thermal effect

Abstract

In this study, we assume that microwave radiation affects hydrogen bonding between dipolar water molecules and through that diffusion in water at constant temperature. The experimental study was performed on the setup of two identical reservoirs filled with pure water and 0.9% NaCl solution and connected by a thin tube. Alterations of NaCl concentration in the reservoir initially filled with pure water were measured using the resistance of the solution as an indicator. The applied 450?MHz continuous-wave microwave field had the maximal specific absorption rate of 0.4?W/kg on the connecting tube. The standard deviation of water temperature in the setup was 0.02?°C during an experiment. Our experimental data demonstrated that microwave exposure makes faster the process of diffusion in water. The time required for reduction of initial resistance of the solution by 10% was 1.7 times shorter with microwave. This result is consistent with the proposed mechanism of low-level microwave effect: microwave radiation, rotating dipolar water molecules, causes high-frequency alterations of hydrogen bonds between water molecules, thereby affects its viscosity and makes faster diffusion.     

The effect of melanin on the bystander effect in human keratinocytes

The influence of melanin on radiation-induced bystander effects has been studied. Melanin is known to be a natural substance with proved radioprotective properties in different organisms and cell lines. It is non-toxic and is effective against acute and chronic irradiation. The lower the radiation dose, the higher the relative impact of melanin protection. In this study influence of melanin on human keratinocytes (HPV-G cells) has been studied using the colony-forming assay. We have shown that bystander donor medium from 0.5 Gy irradiated cells when transferred to unirradiated cells, caused almost the same effect as direct irradiation. Melanin increased the colony-forming ability of bystander recipient cells when it was added into culture medium before irradiation. The effect of melanin added after irradiation was to produce less protection in both the directly irradiated and bystander medium treated groups. The absorption spectrum of the filtered medium is identical to one of the intact culture medium showing that melanin was not present in filtered medium. Thus, it cannot protect recipient cells but reduces the amount of the bystander effect. It is concluded that melanin added before irradiation effectively decreased the radiation dose. The reduction of the impact of the bystander signal on recipient cells when melanin was added to the donor medium after harvest but before filtration, may mean that the bystander signal has a physical component as melanin can absorb all types of physical energy.     

Bubbling and hydra effect in a population system with Allee effect

We present a continuous time predator-prey model and predator’s growth subjected to component Allee effect. The model also includes density dependent mortality of predator. We investigate our model both analytically and numerically, and highlighted the effect of density independent mortality and Allee effect. In our system, we find that a fixed point representing the extinction of predator is always a stable point. When coexistence equilibria exists our system is bistable. We have observed that tristability is possible for our model that includes two stable co-existence fixed point. The most important phenomena which we have observed are hydra effect and cascading effect. Due to component Allee effect in predator the system shows multiple hydra effect. We discuss the phenomenon of bubbling, which indicates increasing and decreasing of amplitudes of cycles. We have presented one-parametric as well as two-parametric bifurcation diagram and also all possible bifurcations that the system could go through.