Competitive Coexistence Research Articles

Temporal Distribution Patterns of Cryptic Brachionus calyciflorus (Rotifera) Species in Relation to Biogeographical Gradient Associated with Latitude.

Sympatric distribution and temporal overlap of cryptic zooplankton species pose a challenge to the framework of the niche differentiation theory and the mechanisms allowing competitor coexistence. We applied the methods of phylogenetic analysis, DNA taxonomy, and statistical analysis to study the temporal distribution patterns of the cryptic B. calyciflorus species, an excellent model, in three lakes, and to explore the putative mechanisms for their seasonal succession and temporal overlap. The results showed that in the warm-temperate Lake Yunlong, B. fernandoi and B. calyciflorus s.s. underwent a seasonal succession, which was largely attributed to their differential adaptation to water temperature. In the subtropical Lake Jinghu, B. fernandoi, B. calyciflorus s.s., and B. dorcas exhibited both seasonal succession and temporal overlap. Seasonal successions were largely attributed to their differential adaptation to temperature, and temporal overlap resulted from their differential responses to algal food concentration. In the tropical Lake Jinniu, B. calyciflorus s.s. persisted throughout the year and overlapped with B. dorcas for 5 months. The temporal overlap resulted from their differential responses to copepod predation. These results indicated that the temporal distribution pattern of the cryptic B. calyciforus species and the mechanism that allows competitor coexistence vary with different climate zones.

Distributed algorithm for nonsmooth multi-coalition games and its application in electricity markets

In this paper, we study distributed nonsmooth multi-coalition games (MCGs), where the players are subject to local convex set constraints and coupled inequality constraints. Different from existing distributed MCGs, our problem involves nonsmooth payoff functions and constraints, relaxes the requirement for communication networks, and only relies on the strict monotonicity of pseudo-gradients. Due to the nonsmoothness of payoff functions and constraints, the weaker communication networks as well as the coexistence of cooperation and competition among players, existing generalized Nash equilibrium (GNE) seeking algorithms cannot solve the problem. Also, they pose obstacles to the algorithm design and analysis, mainly because of the non-global Lipschitz continuity of subgradients and the unconnectedness of subnetworks. To seek the variational GNE (vGNE) of the nonsmooth MCGs, we design a distributed subgradient-based algorithm. We prove that the algorithm converges to the exact vGNE of the nonsmooth MCGs from any initial states. Finally, our result is applied to the electricity market games (EMGs) of smart grids.

미중경쟁과 동북아 지역질서 시나리오

How will the US-China competition reshape the regional order in Northeast Asia? This study analyzes scenarios of US-China competition, focusing on military and economic variables, and examines their implications for regional order. Economic interdependence and military deterrence are means of US-China competition. The balance of military deterrence will be the foremost factor defining the economic relationship between the US and China and neighboring countries. Under the condition of maintaining a deterrent balance, (1) if interdependence continues, competitive interdependence will be formed, but (2) the US or Chinese camp system can be structured along with decoupling. On the other hand, if the deterrent balance collapses, (3) conflictual readjustment of mutual dependence is inevitable, but (4) with decoupling, a Chinese sphere of influence may be formed. The scenario of the end state of the US-China competition provides two implications for Korea's national strategy as a middle country. A security strategy that contributes to the deterrence balance between the US and China is a key task for maintaining an uncomfortable peace. And in order to manage an interdependent system where competition and cooperation coexist, it is necessary to seek the role of a cooperation with in-between powers.

Coexistence in two-species competition with delayed maturation

Inter- and intraspecific competition is most important during the immature life stage for many species of interest, such as multiple coexisting mosquito species that act as vectors of diseases. Mortality caused by competition that occurs during maturation is explicitly modelled in some alternative formulations of the Lotka–Volterra competition model. We generalise this approach by using a distributed delay for maturation time. The kernel of the distributed delay is represented by a truncated Erlang distribution. The shape and rate of the distribution, as well as the position of the truncation, are found to determine the solution at equilibrium. The resulting system of delay differential equations is transformed into a system of ordinary differential equations using the linear chain approximation. Numerical solutions are provided to demonstrate cases where competitive exclusion and coexistence occur. Stability conditions are determined using the nullclines method and local stability analysis. The introduction of a distributed delay promotes coexistence and survival of the species compared to the limiting case of a discrete delay, potentially affecting management of relevant pests and threatened species.

Numerical study of the impact of directed migration of non-indigenous species on invasion scenarios

A mathematical model of competition under conditions of biological invasion, written in the form of a system of nonlinear parabolic equations, is considered. The competition of two closely related species — resident and invader — is studied. The dynamics of populations in a heterogeneous area is determined by local interaction and diffusion. For the invader population, interspecific taxis and directed migration caused by heterogeneity of living conditions are taken into account. In computational experiments, sets of migration parameters corresponding to various invasion scenarios are determined. An analysis of the influence of initial distributions on competitive exclusion and coexistence of species is given.

Political Cold and Economic Hot in Sino-Japanese Diplomatic Relations Since the New Century

Japan is Chinas important neighbor and the only developed country among its neighbors. The relations with Japan are Chinas important external relations. Since the normalization of diplomatic relations between China and Japan in 1972, the two countries have benefited from extensive exchanges and cooperation. In the 21st century, with the changes in the international environment and the reversal of the overall strength comparison between the two countries, the two countries have entered a new period of coexistence of competition and cooperation, and intensified strategic game, showing a situation of cold politics and hot economy. For China, it is an important task in the new century to seek advantages and avoid disadvantages in dealing with its diplomacy with Japan under the background of cold politics and hot economy, so as to ensure the sound and stable relations between the two countries.

Spatial heterogeneity facilitates coexistence between striped hyaenas and sympatric carnivores

AbstractAimInterspecific competition plays a key role in shaping carnivore communities. Top‐down effects can impact the coexistence of superordinate and subordinate competitors and prey across a shared landscape. Limited resources, their abundance and diminishing habitats can all exacerbate interspecific competition. Sometimes, behavioural mechanisms or adaptations are critical for subordinate carnivores to coexist with larger species. Here, we investigated the distribution pattern of the striped hyaena (Hyaena hyaena) population with respect to habitat features, sympatric carnivores and their prey species across a large landscape.LocationWestern and Eastern Ghats, India.TaxonStriped hyaena.MethodsWe collected presence–absence data for hyaenas, tigers, leopards, dholes and their prey using camera‐trapping and indirect sign surveys. Using a random forest algorithm, we modelled the local distribution of hyaenas as a function of important ecological variables, including climate, domestic prey abundance and the predicted probabilities of occurrence of other large carnivores and their prey.ResultsWe found that striped hyaenas were confined to relatively small, discrete areas compared to the three other predators, likely a mechanism for achieving coexistence in the landscape. Our empirical results suggested that hyaenas tend to avoid high occurrence probability areas of their co‐predators at a landscape level but foothold opportunities such as, arid climatic conditions, and prey abundance primarily determined spatial incumbency. Coexistence in an area with low to medium relative abundance of co‐predators offsets the interplay between carcass acquisition and risk associated. The coexistence of species was favoured by altitudinal heterogeneity probably providing denning refugia and also by their preference towards suboptimal thorn forests that sustain a low density of co‐predators.Main ConclusionsOur study showed a desisting impact of large predators on the distribution of the striped hyaena population. Furthermore, we suggest preventing habitat alteration in suboptimal habitats of large carnivores to facilitate coexistence in a shared landscape.

Effects of multiple cations and sintering temperature on microstructure and dielectric properties in Na1/2Ln1/2Cu3Ti4O12 (Ln = Sm and Eu) ceramic materials

Na1/2Eu1/2Cu3Ti4O12 and Na1/2Sm1/2Cu3Ti4O12 dielectric ceramics were synthesized at different sintering temperatures (950, 975 and 1000 °C) by a solid-state reaction method. Phase structure, cation valence state, and dielectric properties of all sintered ceramics were systematically investigated. When the preparation temperature was changed, the Cu+ ion concentration of (Na+, Eu3+) co-doped ceramics changed faster than that of (Na+, Sm3+) co-doped ceramics. Abnormally high dielectric constants of ~ 3.17 × 104 and ~ 1.06 × 104 (at 10 Hz and 303 K) were achieved in Na1/2Sm1/2Cu3Ti4O12 and Na1/2Eu1/2Cu3Ti4O12 ceramics prepared at 950 °C, respectively. However, Na1/2Sm1/2Cu3Ti4O12 and Na1/2Eu1/2Cu3Ti4O12 prepared in high sintering temperature (1000 °C) exhibited a good frequency stability of dielectric permittivity. It was demonstrated that an increasing number of charge carriers induced by the increase of sintering temperature could lead to a competitive coexistence of two polarization mechanisms (surface barrier layer capacitor and internal barrier layer capacitor), further changing the dielectric properties of CaCu3Ti4O12-based ceramics.

The Spatial Pattern Evolution of Rural Settlements and Multi-Scenario Simulations since the Initiation of the Reform and Opening up Policy in China

Since the inception of China’s reform and opening-up policy, the rapidly advancing process of urbanization and the primacy accorded to urban development policies have imparted increasingly profound ramifications on rural domains. Nonetheless, antecedent research has predominantly fixated on urban sprawl, overlooking the spatial metamorphosis of rural settlements and the prospective developmental trajectories within the policy paradigm. Consequently, this inquiry endeavors to scrutinize the evolution of the spatial configuration of rural settlements in She County from the advent of reform and opening-up (1980–2020) utilizing remote sensing data. In tandem, through scenario delineation and the utilization of the CLUE-S model, it aspires to prognosticate the evolving trends in the spatial arrangements of rural settlements in She County by 2035. The empirical findings divulge that (1) The temporal progression of rural settlement spatial configurations in She County over the preceding four decades can be delineated into two discernible phases. From 1980 to 2000, alterations in the number, extent, and spatial morphological attributes of rural settlements remained circumscribed. While the count of rural settlements registered a diminution (by 3), the aggregate extent experienced a marginal augmentation (by 8.45%), concomitant with a gradual gravitation towards regular boundaries, manifesting a stochastic distribution throughout the investigation expanse. Conversely, from 2000 to 2020, the quantity and extent of rural settlements in She County underwent a precipitous augmentation (92 and 36.37%, respectively), characterized by irregular peripheries. (2) The CLUE-S model achieved an overall precision of 0.929, underscoring its applicability in emulating fluctuations in rural settlements. (3) Within the new-type urbanization scenario, the cumulative expanse of rural settlements witnessed a decline of 35.36% compared to the natural development scenario, marked by substantial conversions into grassland and urban land usage. Furthermore, orchestrated planning and directive measures have propelled the consolidation of rural settlements in She County, engendering a more equitable and standardized layout. Under the aegis of the ecological conservation scenario, the total rural settlement area recorded a 0.38% reduction vis-à-vis the natural development scenario, primarily entailing competitive coexistence with arable land, grassland, and urban land usage in spatial terms.

New insight into removal of tetracycline by a two-dimensional graphene-like carbon adsorbent prepared using one-step pyrolysis of spent bleaching earth: Adsorption behaviors, mechanisms and cost analysis

Two-dimensional (2-D) graphene materials have high adsorption capacity for tetracycline because of great specific surface areas and abundant oxygen containing functional groups. Yet their application remains limited because of high costs and complex production processes. Here, a simple strategy for preparing 2-D graphene-like materials is proposed; spent bleaching earth (SBE), a by-product of bleaching edible oil, was initially used to prepare the 2-D material. Residual oils and minerals in SBE comprised the carbon sources and templates required for the 2-D material. The properties of SBE were utilized to synthesize mineral carbon material (SBE@C). This 2-D material (0.34-nm thickness) was investigated by checking the distribution of carbon in the SBE@C interlayer, using electron energy loss spectroscopy (EELS) in a scanning transmission electron microscope. The SBE@C’s resulting 2-D graphene-like structure had an extraordinary uptake capacity for both tetracycline (96.48 mg/g) and sulfamethoxazole (94.24 mg/g). Further, the adsorbent featured excellent stability vis-à-vis the competitive cationic coexistence, an extensive range of pH conditions, and multiple recycled uses (3 times), and its high-performance tetracycline adsorption from a real aquatic environment was also evidenced. Spectroscopic and microscopic studies showed that multiple adsorption mechanisms are involved, namely surface complexation, ion exchange, H-bond interaction, and Π-Π stacking.

Particle size-dependent structural and magnetic properties of Pr0.6-xBixSr0.4MnO3 (x = 0.10 and 0.25)

Nanoparticles of Pr0.6-xBixSr0.4MnO3 (x = 0.10 and 0.25) have been prepared using the swift and cost-effective top-down approach in a high-energy planetary ball mill without any chemical processing and environmental impacts resulting due to pollutants arising from nanoparticle synthesis. The work investigates the role of particle size reduction on the structural and magnetic properties. An increase in milling time from 0 to 240 min results in the drastic reduction of particle size which drops significantly in the initial phase of ball milling i.e., 0–60 min while the microstrain and dislocation densities show nearly monotonic increase. Interestingly the magnetism and size reduction demonstrate a clear one to one correspondence. In both compositions, the paramagnetic (PM) to ferromagnetic (FM) transition, TC decreases and the magnetic transitions broaden both as function Bi and size reduction. The Curie–Weiss analysis of the inverse magnetic susceptibility ({chi }^{-1}) shows a deviation from linearity indicating the presence of the short-range FM interactions above TC which has been understood as Griffith’s phase like singularity. The size reduction can effectively reduce TC, enabling a significant control over tuning of transition temperature and net magnetization. The field dependent magnetization for x = 0.10 demonstrate dominant FM state whereas for x = 0.25, metamagnetic magnetization highlights competitive coexistence of FM and antiferromagnetic (AFM) interactions in the system. With ball milling, the net magnetization decreases, and the metamagnetic behaviour is suppressed. The M–H loops of ball milled nanoparticles are highly unsaturated indicating the enhanced surface disorder in the nanoparticles which can be understood using the core–shell structure.

Quantized pinning bipartite synchronization of fractional-order coupled reaction–diffusion neural networks with time-varying delays

Neural synchronization not only has a significant theoretical role for understanding brain function, but also is important for artificial neural network development. In this paper, a novel and more general directed signed network model, consisting of a set of fractional reaction–diffusion delay neural networks, is articulated. Moreover, we also consider the coexistence of cooperation and competition as a coupling scheme among neurons, which is a mechanism found in biological neural interactions. By designing a new quantized pinning controller based on depth-first algorithm and logarithmic quantization, the sufficient conditions for the bipartite synchronization of the addressed network are given by using Lyapunov method, inequality technique and Green’s formula. In addition, using M-matrix theory, the more applicable bipartite synchronization criteria in the form of low-dimensional linear matrix inequality and the form of network coupling strength threshold are given respectively. This work enriches and improves the previous works. At last, simulation experiments are offered to verify the correctness of our theoretical results.

N, N-bis (2-hydroxyethyl) malonamide based amidoxime functionalized polymer immobilized in biomembranes for highly selective adsorption of uranium(VI)

Amidoxime compounds have been widely used in metal separation and recovery because of their excellent chelating properties to metal ions, especially to uranium (VI). In this study, N, N-bis (2-hydroxyethyl) malonamide was obtained from ethanolamine and dimethyl malonate, and used to prepare a two-dimensional network polymer, then the obtained polymer was immobilized in an environmentally friendly chitosan biomembrane, which enhanced its stability and hydrophobicity, meanwhile the amidoxime functionalization was achieved by oximation reaction of bromoacetonitrile, the application of the material further extends to uranium (VI) separation in solutions. Due to the synergistic action of amide group and amidoxime group, poly (ethanolamine-malonamide) based amidoxime biomembranes (PEA-AOM) showed extraordinary adsorption effect on uranium (VI), among which the saturation adsorption capacity of PEA-AOM-2 was 748.64 mg/g. PEA-AOM-2 also had good reusability (following five cycles of adsorption-desorption, the recovery rate maintained at 88%) and selectivity for uranium (VI), showing satisfactory results in competitive ion coexistence system and simulated seawater experiments. This study demonstrated that PEA-AOM-2 provided a new option for uranium (VI) separation in complex environment and low-concentration uranium background.

A multidimensional interpretation of Marxist globalization theory based on decentralized internet

Abstract To achieve a multidimensional interpretation of Marxist globalization theory, this paper provides a fecundation network facility based on a decentralized internet, thus overcoming various drawbacks of the network where traditional spatial services are located. In the Marxist theory of globalization, the rise from concrete rigor to abstract rigor is an important dialectical transformation of materialist epistemology. It is implied that Marx, based on the principle of mathematical expression of intuition and detail, refined, and deepened the paradigm itself through mathematical tools and mathematical methods, and used mathematical ideas to condense the theory of political economy, making the property of precision reflected in the logic of the paradigm. The 3PL model is established and the basic principles are accurately understood and grasped from mathematical logic according to the labor theory of value, surplus value theory and reproduction theory in Marxism, which provides an important generative logic for constructing a mathematical paradigm of Marxist political economy. The results of the study show that the output efficiency and benefits of fully cooperative networks (L = 0.92, Q = 281.5), after a long period of competition makes the output of the network less efficient, which in turn makes the network as a whole obtain lower returns (L = 0.73, Q = 96.18). In a competitive coexistence network structure, although there are competitive relationships at the core firm level, the network is not greatly affected by this (L = 0.83, Q = 202.92) instead, it will break the monopoly alliance and enliven the local economy. By constructing a rigorous and sophisticated mathematical and theoretical model, the theory of political economy can be made more abstract and scientific, and the analytical and explanatory power of the theory of political economy can be improved.

Competitive interactions and coexistence of sympatric flagship carnivores in Asia.

Understanding the competition and coexistence of flagship carnivores is key to creating strategies for their conservation in the face of global carnivore declines. Although studies exploring the dynamics and competition between tigers (Panthera tigris) and leopards (P. pardus) span decades, there is a lack of understanding regarding the factors that influence their coexistence mechanisms on a broad scale, as well as the drivers determining their exploitative and interference competition. We gathered a comprehensive list of research papers among which 36 papers explored the interspecific interactions between tigers and leopards and tested the influence of biotic and abiotic factors on the coexistence mechanisms along three dimensions using multiple response variables regression models; we also tested the influence of ecological drivers determining the exploitative or interference competition between tigers and leopards. Elevation and ungulate density were the most important predictors in regulating the coexistence mechanisms. Tigers and leopards exhibited more positive relations/higher overlaps as elevation increased in the spatial niche. In addition, they showed a higher dietary overlap in the prey-rich regions. We determined that interference competition between tigers and leopards was less frequently observed in habitats with dense tree cover and homogeneous vegetation structures. Meanwhile, studies with multiple metrics would promote the detection of interference competition. Our study provides new insight into the competitive interactions and coexistence mechanisms of tigers and leopards on a broad scale. Policy-makers and managers should pay more attention to the factors of elevation, prey abundance, and habitat structures for the conservation of tigers and leopards.

Interspecific competition shapes the structural stability of mutualistic networks

Mutualistic networks, such as plant–pollinator networks, have attracted increasing attention in the ecological literature in the last decades, not only because of their fascinating natural history, but also because mutualistic interactions have been shown to play a key role in the maintenance of biodiversity. Although inter-specific competition has long been known to be a crucial driver of species coexistence as well, there is a lack of theory investigating the interplay between the structures of competitive and mutualistic networks when jointly considered. Here, we develop an analytical framework to study the structural stability — the range of conditions under which all species coexist stably, i.e. where the community is both feasible and stable — of ecological communities in which both mutualistic interactions between plants and pollinators and competitive interactions among plants and among pollinators are present. Using the structure of 50 real networks for mutualistic interactions, combined with analytical and numerical analyses, we show that the structure of the competitive network radically alters the necessary conditions for species coexistence in these communities. Our mathematical framework also allows to accurately characterize the structural stability of these systems. Moreover, we introduce a new metric that accurately links the network structures of competitive and mutualistic interactions to species coexistence. Our results highlight the joint role of the structures of different interaction types to understand the stability of ecological communities and facilitate the analysis of similar natural and artificial systems in which mutualism and competition coexist.

“Coopetition” in the presence of team and individual incentives: Evidence from the advice network of a sales organization

Team and individual incentives are ubiquitous in sales, but little is known about their impact on collaboration when they are applied simultaneously. The presence of both types of incentives creates a “coopetitive” environment, where forces of collaboration and competition coexist. We examine how such environments impact the likelihood (Study 1) and the effectiveness (Study 2) of collaboration in the form of advice exchange. Exponential random graph modeling (ERGM) of network data of 540 salespeople reveals that individual incentives promote advice seeking but discourage advice giving, and team incentives stimulate advice giving but reduce advice seeking (Study 1). We also find that the effectiveness of advice depends on advice givers (Study 2). In particular, when advice givers have diverse team incentives, the advice is more effective and the need for additional advice is reduced, but when advice givers have diverse individual incentives, the advice is less effective and additional advice helps.

A Reaction–Diffusion–Advection Chemostat Model in a Flowing Habitat: Mathematical Analysis and Numerical Simulations

This paper is concerned with a reaction–diffusion–advection chemostat model with two species growing and competing for a single-limited resource. By taking the growth rates of the two species as variable parameters, we study the effect of growth rates on the dynamics of this system. It is found that there exist several critical curves, which may classify the dynamics of this system into three scenarios: (1) extinction of both species; (2) competitive exclusion; (3) coexistence. Moreover, we take numerical approaches to further understand the potential behaviors of the above critical curves and observe that the bistable phenomenon can occur, besides competitive exclusion and coexistence. To further study the effect of advection and diffusion on the dynamics of this system, we present the bifurcation diagrams of positive equilibrium solutions of the single species model and the two-species model with the advection rates and the diffusion rates increasing, respectively. These numerical results indicate that advection and diffusion play a key role in determining the dynamics of two species competing in a flow reactor.

On a competition model in stream environments: The effects of seasonal pulses and advection

A diffusion-advection competition model with different pulses has been investigated in order to understand how the impulsive intervention affects the dynamics and alters the competition state of two competitors in open advective environments. The threshold values are introduced as the principal eigenvalues of the periodic problems with pulses and defined by the spectral radius of a time-T map. We have obtained two critical advection curves depending on pulses that determine the stability of the periodic steady states and have computed these numerically. The dynamics of two competitors in open advective environments such as competition exclusion, co-extinction, coexistence and bistability have been classified. By applying different impulsive effects, simulation analysis shows interesting scenarios, and reveals that a tradeoff between two different impulsive interventions and movements can be found in order to improve sustainable ecological development and economic benefits.

Interactions between fitness components across the life cycle constrain competitor coexistence.

Numerous mechanisms can promote competitor coexistence. Yet, these mechanisms are often considered in isolation from one another. Consequently, whether multiple mechanisms shaping coexistence combine to promote or constrain species coexistence remains an open question. Here, we aim to understand how multiple mechanisms interact within and between life stages to determine frequency-dependent population growth, which has a key role stabilizing local competitor coexistence. We conducted field experiments in three lakes manipulating relative frequencies of two Enallagma damselfly species to evaluate demographic contributions of three mechanisms affecting different fitness components across the life cycle: the effect of resource competition on individual growth rate, predation shaping mortality rates, and mating harassment determining fecundity. We then used a demographic model that incorporates carry-over effects between life stages to decompose the relative effect of each fitness component generating frequency-dependent population growth. This decomposition showed that fitness components combined to increase population growth rates for one species when rare, but they combined to decrease population growth rates for the other species when rare, leading to predicted exclusion in most lakes. Because interactions between fitness components within and between life stages vary among populations, these results show that local coexistence is population specific. Moreover, we show that multiple mechanisms do not necessarily increase competitor coexistence, as they can also combine to yield exclusion. Identifying coexistence mechanisms in other systems will require greater focus on determining contributions of different fitness components across the life cycle shaping competitor coexistence in a way that captures the potential for population-level variation.