scholarly journals Frequency-dependent fitness induces multistability in coevolutionary dynamics

2012 ◽  
Vol 9 (77) ◽  
pp. 3387-3396 ◽  
Author(s):  
Hinrich Arnoldt ◽  
Marc Timme ◽  
Stefan Grosskinsky
Keyword(s):  
Frequency Dependence ◽  
Evolutionary Dynamics ◽  
Metastable States ◽  
Theoretical Research ◽  
Nonlinear Frequency ◽  
Frequency Dependent ◽  
Switching Dynamics ◽  
Game Theoretic ◽  
System Properties ◽  
The Impact

Evolution is simultaneously driven by a number of processes such as mutation, competition and random sampling. Understanding which of these processes is dominating the collective evolutionary dynamics in dependence on system properties is a fundamental aim of theoretical research. Recent works quantitatively studied coevolutionary dynamics of competing species with a focus on linearly frequency-dependent interactions, derived from a game-theoretic viewpoint. However, several aspects of evolutionary dynamics, e.g. limited resources, may induce effectively nonlinear frequency dependencies. Here we study the impact of nonlinear frequency dependence on evolutionary dynamics in a model class that covers linear frequency dependence as a special case. We focus on the simplest non-trivial setting of two genotypes and analyse the co-action of nonlinear frequency dependence with asymmetric mutation rates. We find that their co-action may induce novel metastable states as well as stochastic switching dynamics between them. Our results reveal how the different mechanisms of mutation, selection and genetic drift contribute to the dynamics and the emergence of metastable states, suggesting that multistability is a generic feature in systems with frequency-dependent fitness.

scholarly journals Adaptation, Clonal Interference, and Frequency-Dependent Interactions in a Long-Term Evolution Experiment with Escherichia coli

2015 ◽  
Author(s):  
Rohan Maddamsetti ◽  
Richard E. Lenski ◽  
Jeffrey E. Barrick
Keyword(s):  
Escherichia Coli ◽  
Frequency Dependence ◽  
Evolutionary Dynamics ◽  
Selective Sweeps ◽  
Clonal Interference ◽  
Beneficial Mutations ◽  
Frequency Dependent ◽  
Evolution Experiment ◽  
History Of

Twelve replicate populations of Escherichia coli have been evolving in the laboratory for more than 25 years and 60,000 generations. We analyzed bacteria from whole-population samples frozen every 500 generations through 20,000 generations for one well-studied population, called Ara???1. By tracking 42 known mutations in these samples, we reconstructed the history of this population???s genotypic evolution over this period. The evolutionary dynamics of Ara???1 show strong evidence of selective sweeps as well as clonal interference between competing lineages bearing different beneficial mutations. In some cases, sets of several mutations approached fixation simultaneously, often conveying no information about their order of origination; we present several possible explanations for the existence of these mutational cohorts. Against a backdrop of rapid selective sweeps both earlier and later, we found that two clades coexisted for over 6000 generations before one drove the other extinct. In that time, at least nine mutations arose in the clade that prevailed. We found evidence that the clades evolved a frequency-dependent interaction, which prevented the competitive exclusion of either clade, but which eventually collapsed as beneficial mutations accumulated in the clade that prevailed. Clonal interference and frequency dependence can occur even in the simplest microbial populations. Furthermore, frequency dependence may generate dynamics that extend the period of coexistence that would otherwise be sustained by clonal interference alone.

Frequency dependence of CO2 elimination and respiratory resistance in monkeys

1985 ◽  
Vol 58 (2) ◽  
pp. 653-657 ◽  
Author(s):  
J. W. Watson ◽  
A. C. Jackson
Keyword(s):  
Frequency Dependence ◽  
Nonlinear Frequency ◽  
Frequency Dependent ◽  
Dependent Behavior ◽  
Frequency Independent ◽  
Respiratory System Resistance ◽  
The Relationship ◽  
High Frequency Oscillatory ◽  
Large Frequency ◽  
Co2 Elimination

In dogs, respiratory system resistance (Rrs) is frequency independent, and during high-frequency oscillatory ventilation (HFO) the relationship between CO2 elimination (VCO2) and frequency is linear. In contrast, we found in rabbits a large frequency-dependent decrease in Rrs with increasing frequency along with a nonlinear relationship between frequency and VCO2 (J. Appl. Physiol. 57: 354–359, 1984). We proposed that frequency dependent mechanical properties of the lung account for inter-species differences in the frequency dependence of gas exchange during HFO. In the current study we tested this hypothesis further by measuring VCO2 and Rrs as a function of frequency in a species of monkey (Macaca radiata). In these monkeys, Rrs decreased minimally between 4 and 8 Hz and in general increased at higher frequencies, whereas VCO2 was linearly related to frequency. This is further evidence supporting the hypothesis that nonlinear frequency-VCO2 behavior during HFO is related to frequency-dependent behavior in Rrs.

scholarly journals The Impact of the Frequency Dependence of Soil Electrical Parameters on Lightning Overvoltages Developed in a 138 kV Transmission Line

2020 ◽  
Author(s):  
Felipe De Vasconcellos ◽  
Fernando Moreira ◽  
Rafael Alípio
Keyword(s):  
Transmission Line ◽  
Frequency Dependence ◽  
Soil Parameters ◽  
Construction Time ◽  
Frequency Dependent ◽  
Percentage Decrease ◽  
Conservative Estimation ◽  
Line Construction ◽  
The Impact ◽  
Length Reduction

This study evaluates the overvoltages developed due to direct lightning strokes to a 138-kV transmission line tower top comparing constant and frequency-dependent soil parameters. ATP(Alternative Transients Program) was used to simulate the phenomena. The inclusion of the frequency-dependent soil parameters causes a percentage decrease of the overvoltage peaks when compared with constant soil parameters of around 15% to 33% for first strokes considering values of soil resistivity of 500 Ω.m and 2.500 Ω.m. It was also studied the counterpoise cables length reduction in order to maintain equivalent overvoltage levels to those of simulations with constant parameters. This reduction ranged from 25 to 55%, which could contribute to economic gains as well as operational efficiency in the grounding systems and transmission line construction time. Therefore, disregarding the frequency dependence of the soil parameters in simulations may lead to an overly conservative estimation of the lightning performance of the transmission line.

scholarly journals Transient Analysis of Multiphase Transmission Lines Located above Frequency-Dependent Soils

Energies ◽  
2021 ◽  
Vol 14 (17) ◽  
pp. 5252
Author(s):  
Tainá Fernanda Garbelim Pascoalato ◽  
Anderson Ricardo Justo de Araújo ◽  
Pablo Torrez Caballero ◽  
Jaimis Sajid Leon Colqui ◽  
Sérgio Kurokawa
Keyword(s):  
Power Systems ◽  
Frequency Dependence ◽  
Transmission Lines ◽  
Transient Analysis ◽  
Transient Responses ◽  
Frequency Dependent ◽  
Lightning Strikes ◽  
Significant Difference ◽  
Soil Conductivity ◽  
The Impact

This paper evaluates the influence of frequency-dependent soil conductivity and permittivity in the transient responses of single- and double-circuit transmission lines including the ground wires subjected to lightning strikes. We use Nakagawa’s approach to compute the ground-return impedance and admittance matrices where the frequency-dependent soil is modeled using Alípio and Visacro’s model. We compare some elements of these matrices with those calculated by Carson’s approach which assumes the frequency constant. Results show that a significant difference can be obtained in high resistive soils for these elements in impedance and admittance matrices. Then, we compute the transient responses for single- and double-circuit lines with ground wires located above soils of 500, 1000, 5000, and 10,000 Ω·m considering the frequency constant and frequency-dependent parameters generated for two lightning strikes (subsequent stroke and Gaussian pulse). We demonstrate that the inclusion of frequency dependence of soil results in an expressive reduction of approximately 26.15% and 42.75% in the generated voltage peaks in single- and double-circuit lines located above a high-resistive soil. These results show the impact of the frequency-dependent soils that must be considered for a precise transient analysis in power systems.

The impact of the new media on public relations in the public administration in Kurdistan Region

2019 ◽  
Vol 7 (1) ◽  
pp. 268-288
Author(s):  
Dlan Ismail Mawlud ◽  
Hoshyar Mozafar Ali
Keyword(s):  
Information Technology ◽  
New Media ◽  
Public Relations ◽  
Public Administration ◽  
Management System ◽  
Theoretical Research ◽  
Kurdistan Region ◽  
The Public ◽  
Government Institutions ◽  
The Impact

The development of technology, information technology and various means of communication have a significant impact on public relations activity; especially in government institutions. Many government institutions have invested these means in their management system, in order to facilitate the goals of the institution, and ultimately the interaction between the internal and external public. In this theoretical research, I tried to explain the impact of the new media on public relations in the public administration, based on the views of specialists. The aim of the research is to know the use of the new media of public relations and how in the system of public administration, as well as, Explaining the role it plays in public relations activities of government institutions. Add to this, analyzing the way of how new media and public relations participate in the birth of e-government. In the results, it is clear that the new media has facilitated public relations between the public and other institutions, as it strengthened relations between them

scholarly journals Improving Drought Tolerance in Mungbean (Vigna radiata L. Wilczek): Morpho-Physiological, Biochemical and Molecular Perspectives

Agronomy ◽  
2021 ◽  
Vol 11 (8) ◽  
pp. 1534
Author(s):  
Chandra Mohan Singh ◽  
Poornima Singh ◽  
Chandrakant Tiwari ◽  
Shalini Purwar ◽  
Mukul Kumar ◽  
...  
Keyword(s):  
Drought Stress ◽  
Drought Tolerance ◽  
Crop Production ◽  
Mitigation Strategies ◽  
Theoretical Research ◽  
Whole Genome Sequence ◽  
Complex Nature ◽  
Drought Tolerant ◽  
Breeding Programmes ◽  
The Impact

Drought stress is considered a severe threat to crop production. It adversely affects the morpho-physiological, biochemical and molecular functions of the plants, especially in short duration crops like mungbean. In the past few decades, significant progress has been made towards enhancing climate resilience in legumes through classical and next-generation breeding coupled with omics approaches. Various defence mechanisms have been reported as key players in crop adaptation to drought stress. Many researchers have identified potential donors, QTLs/genes and candidate genes associated to drought tolerance-related traits. However, cloning and exploitation of these loci/gene(s) in breeding programmes are still limited. To bridge the gap between theoretical research and practical breeding, we need to reveal the omics-assisted genetic variations associated with drought tolerance in mungbean to tackle this stress. Furthermore, the use of wild relatives in breeding programmes for drought tolerance is also limited and needs to be focused. Even after six years of decoding the whole genome sequence of mungbean, the genome-wide characterization and expression of various gene families and transcriptional factors are still lacking. Due to the complex nature of drought tolerance, it also requires integrating high throughput multi-omics approaches to increase breeding efficiency and genomic selection for rapid genetic gains to develop drought-tolerant mungbean cultivars. This review highlights the impact of drought stress on mungbean and mitigation strategies for breeding high-yielding drought-tolerant mungbean varieties through classical and modern omics technologies.

Augmenting Employees’ Efforts in Innovation

2021 ◽  
pp. 097674792198917
Author(s):  
Nikita Jain
Keyword(s):  
Theoretic Model ◽  
Wrongful Discharge ◽  
Equilibrium Level ◽  
Game Theoretic ◽  
Game Theoretic Model ◽  
The Impact

Strong labour laws play a major role in motivating innovation among employees. It has been found in the literature that stringency of labour laws is positively linked with employees’ efforts in innovation, in particular, wrongful discharge laws (WDL). However, employees may also bring nuisance suits against employers. Usually, the result of these suits is that both parties settle with each other. Thus, even if employees are justly dismissed, they may be able to bring nuisance suits against employers and gain a settlement amount. This article investigates how the possibility of nuisance suits affects the impact of WDL on employees’ efforts in innovation. In this respect, a game-theoretic model is developed in the article to find the equilibrium level of employees’ efforts in the presence of nuisance suits, where there is a possibility of employees getting discharged from the firm. I find that if nuisance suits are a possibility, the stringency of WDL has no impact on employees’ efforts if defence cost of the firm is low; but for higher defence costs, WDL affects employees’ efforts. The efforts exerted by an employee are found to be weakly increasing in the defence costs of the firm.

scholarly journals The importance of species interactions in eco-evolutionary community dynamics under climate change

2021 ◽  
Vol 12 (1) ◽  
Author(s):  
Anna Åkesson ◽  
Alva Curtsdotter ◽  
Anna Eklöf ◽  
Bo Ebenman ◽  
Jon Norberg ◽  
...  
Keyword(s):  
Climate Change ◽  
Species Interactions ◽  
Community Dynamics ◽  
Evolutionary Dynamics ◽  
Negative Impact ◽  
Trophic Levels ◽  
Temperature Dependent ◽  
Modeling Framework ◽  
Impact Of Climate Change ◽  
The Impact

AbstractEco-evolutionary dynamics are essential in shaping the biological response of communities to ongoing climate change. Here we develop a spatially explicit eco-evolutionary framework which features more detailed species interactions, integrating evolution and dispersal. We include species interactions within and between trophic levels, and additionally, we incorporate the feature that species’ interspecific competition might change due to increasing temperatures and affect the impact of climate change on ecological communities. Our modeling framework captures previously reported ecological responses to climate change, and also reveals two key results. First, interactions between trophic levels as well as temperature-dependent competition within a trophic level mitigate the negative impact of climate change on biodiversity, emphasizing the importance of understanding biotic interactions in shaping climate change impact. Second, our trait-based perspective reveals a strong positive relationship between the within-community variation in preferred temperatures and the capacity to respond to climate change. Temperature-dependent competition consistently results both in higher trait variation and more responsive communities to altered climatic conditions. Our study demonstrates the importance of species interactions in an eco-evolutionary setting, further expanding our knowledge of the interplay between ecological and evolutionary processes.

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