scholarly journals Signals and Spite in Fluctuating Populations

2019 ◽  
Vol 2 (1) ◽  
pp. 137-146
Author(s):  
Rory Smead ◽  
Patrick Forber

AbstractSpite (in the biological or evolutionary sense) is behavior that harms others at a cost to the actor. The presence of spite in human and animal populations presents an evolutionary puzzle. Recent work has suggested small populations and pre-play signaling can have a significant effect on the evolution of spite. Here, we use computational methods to explore these factors in fluctuating populations that may go extinct. We find that the presence of spite can make a population significantly more likely to go extinct, but that this does not preclude the possibility of spite reliably evolving. Additionally, we find that the stochastic effects of small fluctuating populations allow for the evolution and predominance of signal-mediated conditional spite across a wide range of conditions. These results suggest that directed harm, even if costly, can play a significant early role in the evolution of social behaviors and this provides a possible origin for punishment.

2020 ◽  
Vol 55 (S3) ◽  
pp. 14-45

Although ion channels are crucial in many physiological processes and constitute an important class of drug targets, much is still unclear about their function and possible malfunctions that lead to diseases. In recent years, computational methods have evolved into important and invaluable approaches for studying ion channels and their functions. This is mainly due to their demanding mechanism of action where a static picture of an ion channel structure is often insufficient to fully understand the underlying mechanism. Therefore, the use of computational methods is as important as chemical-biological based experimental methods for a better understanding of ion channels. This review provides an overview on a variety of computational methods and software specific to the field of ion-channels. Artificial intelligence (or more precisely machine learning) approaches are applied for the sequence-based prediction of ion channel family, or topology of the transmembrane region. In case sufficient data on ion channel modulators is available, these methods can also be applied for quantitative structureactivity relationship (QSAR) analysis. Molecular dynamics (MD) simulations combined with computational molecular design methods such as docking can be used for analysing the function of ion channels including ion conductance, different conformational states, binding sites and ligand interactions, and the influence of mutations on their function. In the absence of a three-dimensional protein structure, homology modelling can be applied to create a model of your ion channel structure of interest. Besides highlighting a wide range of successful applications, we will also provide a basic introduction to the most important computational methods and discuss best practices to get a rough idea of possible applications and risks.


Author(s):  
Daniel Butt

This chapter examines the limitations of both command-and-control and market-based legal mechanisms in the pursuit of environmental justice. If the environment is to be protected to at least a minimally acceptable degree, approaches that focus on the coercive force of the state must be complemented by the development of an “ecological ethos,” whereby groups and individuals are motivated to act with non-self-interested concern for the environment. The need for this ethos means that the state is dependent on the cooperation of a wide range of non-state actors. Recent work on environmental governance emphasizes the delegation of aspects of governing to such actors and supports efforts to increase popular participation in governmental processes. The chapter therefore advocates a governance approach that seeks to rectify some of the limitations of state-led environmental law, while encouraging popular participation in a way that can encourage the development of an ecological ethos among the citizenry.


1992 ◽  
Vol 19 (2) ◽  
pp. 160-164 ◽  
Author(s):  
Richard E. Hoare

The varying reasons are outlined for needing to control the movements or otherwise manage a wide range of African animal wildlife species by means of fencing. In all cases there is an underlying conflict of interest between people and animals — principally the larger mammals. Fencing is seen as the most powerful tool in this process of land-use division, and high expectations of fences are held by people who are adversely affected by wildlife activities and similarly by many conservationists. To date the main determinants in the siting and construction of fences have been political pressure or the availability of funds; wildlife fencing is perhaps the only factor having a substantial influence on ecosystems and animal populations that has remained virtually devoid of any serious input of ecological knowledge, of systematic investigation, or of environmental legislation.The wild species requiring management are many and varied in individual size, group size, and dispersal patterns; they also exhibit an array of special behaviours when confronted with a barrier. This means that any barrier will come under very variable levels and types of challenge, and that the effects of it on the biology of both target and non-target species must be carefully considered.Research on the behaviour of animals at fences has been limited, being mostly confined to domestic species or non-African wildlife. Certainly, very little systematic investigation has been carried out to determine whether fences have achieved their objectives or been economically justified, and to what extent they have caused environmental side-effects on the population dynamics of animals or the disturbance of plant communities.Current evidence suggests that electric or power fences are an increasingly efficient way of managing wild mammals and that fencing programmes should become more deflecting than encircling. Fences create ‘hard edges’ between dissimilar forms of land-use and cause long-term inflexibility that limits planning and forecloses options. As the pressure for land becomes more and more acute, the control of wildlife with the help of fences needs to develop into a specialized field of its own, based on sounder ecological, sociological, and economic, principles than hitherto, within the expanding scope of adaptive wildlife management.


2018 ◽  
Vol 16 (2) ◽  
pp. 144-163 ◽  
Author(s):  
John Harding ◽  
Cecilie Brandt-Olsen

Combining graph-based parametric design with metaheuristic solvers has to date focused solely on performance-based criteria and solving clearly defined objectives. In this article, we outline a new method for combining a parametric modelling environment with an interactive Cluster-Orientated Genetic Algorithm. In addition to performance criteria, evolutionary design exploration can be guided through choice alone, with user motivation that cannot be easily defined. As well as numeric parameters forming a genotype, the evolution of whole parametric definitions is discussed through the use of genetic programming. Visualisation techniques that enable mixing small populations for interactive evolution with large populations for performance-based optimisation are discussed, with examples from both academia and industry showing a wide range of applications.


Author(s):  
Keith J. Topping

Both peer tutoring and cooperative learning are types of peer assisted learning; they involve people from similar social groupings who are not professional teachers helping each other to learn and learning themselves by teaching. Peer tutoring usually involves pairs of students, one in the role of tutor and the other as tutee, with the more able or experienced member helping the other to learn material which is new to the tutor but not to the tutee. By contrast, cooperative learning is usually done in small groups of perhaps four students, often of mixed ability. The group works toward a consensus on a problem. Because it is easier to dominate or hide in a group, roles are often assigned to each group member. Earlier perspectives tended to use the theories of Piaget and Vygotsky, perhaps with some consideration of Bandura and Dewey. Chi, King, and Graesser have been prominent in more recent work. However, a theoretical perspective is offered that integrates these elements with more practical issues. In general, both peer tutoring and cooperative learning “work”— in a wide range of curricular subjects and with a wide range of ages. Given the appropriate form of organization, cognitive gains ensue for both helpers and those who are helped. This is not the main research issue, which is exploring how and why these practices work, in order to improve effectiveness. There are several meta-analyses (a statistical procedure for combining data from multiple studies) which are relevant, and beyond this, key individual papers of specific importance are highlighted. Over the years, we have become wiser about some of the key issues. In peer tutoring, same-ability tutoring has appeared in recent years, sometimes reciprocal, and we need to know under what conditions it works. Cooperative learning has issues regarding the most effective roles for group members and how these integrate with student ability and personality. There has also been much recent work in online peer tutoring which raises different issues. The existing literature is well-developed since these are not new methods. Future research should include more tightly defined studies focusing on more minor variables of context and organization. Many teachers will say they use both peer tutoring and cooperative learning, but very often they overestimate how often anything like good practice takes place. Simply putting students together and hoping for the best will not do, although it might have mild effects. Teachers using these methods need to be clear about what organizational parameters are vital in their context with their type of peer assisted learning. These features then need to be maximized in practice and an eye must be kept on implementation fidelity throughout. Education administrators need to organize professional development for teachers which is thorough, including initial instruction and practice followed up by support and monitoring in the classroom.


2019 ◽  
Vol 375 (1792) ◽  
pp. 20190164 ◽  
Author(s):  
Lei Zhao ◽  
Yuqing Hou ◽  
Nathan A. McNeill ◽  
George B. Witman

Nearly all motile cilia and flagella (terms here used interchangeably) have a ‘9+2’ axoneme containing nine outer doublet microtubules and two central microtubules. The central pair of microtubules plus associated projections, termed the central apparatus (CA), is involved in the control of flagellar motility and is essential for the normal movement of ‘9+2’ cilia. Research using the green alga Chlamydomonas reinhardtii , an important model system for studying cilia, has provided most of our knowledge of the protein composition of the CA, and recent work using this organism has expanded the number of known and candidate CA proteins nearly threefold. Here we take advantage of this enhanced proteome to examine the genomes of a wide range of eukaryotic organisms, representing all of the major phylogenetic groups, to identify predicted orthologues of the C. reinhardtii CA proteins and explore how widely the proteins are conserved and whether there are patterns to this conservation. We also discuss in detail two contrasting groups of CA proteins—the ASH-domain proteins, which are broadly conserved, and the PAS proteins, which are restricted primarily to the volvocalean algae. This article is part of the Theo Murphy meeting issue ‘Unity and diversity of cilia in locomotion and transport’.


Sensors ◽  
2019 ◽  
Vol 19 (16) ◽  
pp. 3531 ◽  
Author(s):  
Lorenzo Manoni ◽  
Claudio Turchetti ◽  
Laura Falaschetti ◽  
Paolo Crippa

Wearable devices offer a convenient means to monitor biosignals in real time at relatively low cost, and provide continuous monitoring without causing any discomfort. Among signals that contain critical information about human body status, electromyography (EMG) signal is particular useful in monitoring muscle functionality and activity during sport, fitness, or daily life. In particular surface electromyography (sEMG) has proven to be a suitable technique in several health monitoring applications, thanks to its non-invasiveness and ease to use. However, recording EMG signals from multiple channels yields a large amount of data that increases the power consumption of wireless transmission thus reducing the sensor lifetime. Compressed sensing (CS) is a promising data acquisition solution that takes advantage of the signal sparseness in a particular basis to significantly reduce the number of samples needed to reconstruct the signal. As a large variety of algorithms have been developed in recent years with this technique, it is of paramount importance to assess their performance in order to meet the stringent energy constraints imposed in the design of low-power wireless body area networks (WBANs) for sEMG monitoring. The aim of this paper is to present a comprehensive comparative study of computational methods for CS reconstruction of EMG signals, giving some useful guidelines in the design of efficient low-power WBANs. For this purpose, four of the most common reconstruction algorithms used in practical applications have been deeply analyzed and compared both in terms of accuracy and speed, and the sparseness of the signal has been estimated in three different bases. A wide range of experiments are performed on real-world EMG biosignals coming from two different datasets, giving rise to two different independent case studies.


1995 ◽  
Vol 22 (1) ◽  
pp. 89 ◽  
Author(s):  
S. Boutin

Fluctuating populations of small mammals provide an excellent opportunity to study the functional and numerical responses of predators because of the wide range in prey density that occurs. I reinterpret data from six studies that have examined the role of predation in the population dynamics of voles in California, southern Sweden and western Finland, of snowshoe hares in northern Canada, and of house mice and rabbits in Australia. Most studies have measured functional responses by relying on changes in diet as reflected by scat or stomach contents. These methods are probably biased toward showing predator satiation. Contrary to previous conclusions I find that there is little evidence for non-linear (Type 111) functional-response curves or predator satiation at high prey densities. Recent studies indicate that the functional and numerical responses of predators can be rapid and strong enough to initiate cyclic declines, dampen fluctuations, or even cause stable numbers. The exception to this appears to be the irruptions of mice and rabbits in Australia. I propose a general explanation for the role of predation whereby the effect of predation is largely dependent on the entire prey community. When potentially cyclic prey are a small component of the overall prey biomass, generalist predators are able to prevent fluctuations by strong functional or numerical responses. As the prey community becomes dominated by a few species that fluctuate, limit cycles predominate. Limit cycles turn into irruptive population dynamics when seasonal prey reproduction is eliminated because of extended periods of vegetation growth (vegetation flushes following drought). In the future we must test assumptions underlying the way we study predation by telemetric monitoring of prey mortality and by experimentally manipulating predation.


2017 ◽  
Vol 284 (1868) ◽  
pp. 20171666 ◽  
Author(s):  
Ian S. Pearse ◽  
Jalene M. LaMontagne ◽  
Walter D. Koenig

Mast seeding, or masting, is the highly variable and spatially synchronous production of seeds by a population of plants. The production of variable seed crops is typically correlated with weather, so it is of considerable interest whether global climate change has altered the variability of masting or the size of masting events. We compiled 1086 datasets of plant seed production spanning 1900–2014 and from around the world, and then analysed whether the coefficient of variation (CV) in seed set, a measure of masting, increased over time. Over this 115-year period, seed set became more variable for plants as a whole and for the particularly well-studied taxa of conifers and oaks. The increase in CV corresponded with a decrease in the long-term mean of seed set of plant species. Seed set CV increased to a greater degree in plant taxa with a tendency towards masting. Seed set is becoming more variable among years, especially for plant taxa whose masting events are known to affect animal populations. Such subtle change in reproduction can have wide-ranging effects on ecosystems because seed crops provide critical resources for a wide range of taxa and have cascading effects throughout food webs.


1999 ◽  
Vol 73 (3) ◽  
pp. 251-261 ◽  
Author(s):  
B. K. EPPERSON ◽  
Z. HUANG ◽  
T.-Q. LI

Various spatial autocorrelation statistics have been widely used both in theoretical population genetics and to study the spatial distribution of diploid genotypes in many plant and animal populations. However, previous simulation studies have considered only diallelic loci. In this paper, we use a large number of space–time simulations to characterize for the first time the parametric and statistical values of Moran's I-statistics for converted individual genotypes as well as for join- count statistics. A wide range of levels of dispersal and numbers of alleles and allele frequencies are modelled and the results reveal the different general effects of each of these factors on these statistics. We also examine the range of appropriate sampling designs and sizes for which predicted values can be interpolated for specific sampling schemes for any given population genetic field survey. Numbers of alleles and allele frequencies each affect some statistics but not others. The results indicate generally low standard deviations. The results also develop precise and efficient methods of estimating gene dispersal, based on the various autocorrelation measures of standing spatial patterns of genetic variation within populations. The results also extend these methods to loci with multiple alleles, typical of those studied through modern molecular methods.


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