scholarly journals Analysis of statistical correlations between properties of adaptive walks in fitness landscapes

2020 ◽  
Vol 7 (1) ◽  
pp. 192118
Author(s):  
Sandro M. Reia ◽  
Paulo R. A. Campos
Keyword(s):  
Experimental Evolution ◽  
Fitness Landscape ◽  
Shortest Paths ◽  
Fitness Landscapes ◽  
The Other ◽  
Attraction Basin ◽  
Statistical Correlations ◽  
Adaptive Walks ◽  
Nk Landscapes ◽  
The Relationship

The fitness landscape metaphor has been central in our way of thinking about adaptation. In this scenario, adaptive walks are idealized dynamics that mimic the uphill movement of an evolving population towards a fitness peak of the landscape. Recent works in experimental evolution have demonstrated that the constraints imposed by epistasis are responsible for reducing the number of accessible mutational pathways towards fitness peaks. Here, we exhaustively analyse the statistical properties of adaptive walks for two empirical fitness landscapes and theoretical NK landscapes. Some general conclusions can be drawn from our simulation study. Regardless of the dynamics, we observe that the shortest paths are more regularly used. Although the accessibility of a given fitness peak is reasonably correlated to the number of monotonic pathways towards it, the two quantities are not exactly proportional. A negative correlation between predictability and mean path divergence is established, and so the decrease of the number of effective mutational pathways ensures the convergence of the attraction basin of fitness peaks. On the other hand, other features are not conserved among fitness landscapes, such as the relationship between accessibility and predictability.

scholarly journals Adaptive walks on high-dimensional fitness landscapes and seascapes with distance-dependent statistics

2018 ◽  
Author(s):  
Atish Agarwala ◽  
Daniel S. Fisher
Keyword(s):  
Evolutionary Dynamics ◽  
Fitness Landscape ◽  
Broad Class ◽  
Fitness Landscapes ◽  
High Dimensional ◽  
General Function ◽  
Long Distance ◽  
Future Evolution ◽  
Adaptive Mutations ◽  
Adaptive Walks

AbstractThe dynamics of evolution is intimately shaped by epistasis — interactions between genetic elements which cause the fitness-effect of combinations of mutations to be non-additive. Analyzing evolutionary dynamics that involves large numbers of epistatic mutations is intrinsically difficult. A crucial feature is that the fitness landscape in the vicinity of the current genome depends on the evolutionary history. A key step is thus developing models that enable study of the effects of past evolution on future evolution. In this work, we introduce a broad class of high-dimensional random fitness landscapes for which the correlations between fitnesses of genomes are a general function of genetic distance. Their Gaussian character allows for tractable computational as well as analytic understanding. We study the properties of these landscapes focusing on the simplest evolutionary process: random adaptive (uphill) walks. Conventional measures of “ruggedness” are shown to not much affect such adaptive walks. Instead, the long-distance statistics of epistasis cause all properties to be highly conditional on past evolution, determining the statistics of the local landscape (the distribution of fitness-effects of available mutations and combinations of these), as well as the global geometry of evolutionary trajectories. In order to further explore the effects of conditioning on past evolution, we model the effects of slowly changing environments. At long times, such fitness “seascapes” cause a statistical steady state with highly intermittent evolutionary dynamics: populations undergo bursts of rapid adaptation, interspersed with periods in which adaptive mutations are rare and the population waits for more new directions to be opened up by changes in the environment. Finally, we discuss prospects for studying more complex evolutionary dynamics and on broader classes of high-dimensional landscapes and seascapes.

scholarly journals The fitness landscape of the codon space across environments

2018 ◽  
Author(s):  
Inès Fragata ◽  
Sebastian Matuszewski ◽  
Mark A. Schmitz ◽  
Thomas Bataillon ◽  
Jeffrey D. Jensen ◽  
...  
Keyword(s):  
Amino Acid ◽  
Evolutionary Dynamics ◽  
Fitness Landscape ◽  
Fitness Landscapes ◽  
Synonymous Mutations ◽  
Landscape Studies ◽  
Fitness Effects ◽  
Bayesian Monte Carlo ◽  
The Relationship

AbstractFitness landscapes map the relationship between genotypes and fitness. However, most fitness landscape studies ignore the genetic architecture imposed by the codon table and thereby neglect the potential role of synonymous mutations. To quantify the fitness effects of synonymous mutations and their potential impact on adaptation on a fitness landscape, we use a new software based on Bayesian Monte Carlo Markov Chain methods and reestimate selection coefficients of all possible codon mutations across 9 amino-acid positions in Saccharomyces cerevisiae Hsp90 across 6 environments. We quantify the distribution of fitness effects of synonymous mutations and show that it is dominated by many mutations of small or no effect and few mutations of larger effect. We then compare the shape of the codon fitness landscape across amino-acid positions and environments, and quantify how the consideration of synonymous fitness effects changes the evolutionary dynamics on these fitness landscapes. Together these results highlight a possible role of synonymous mutations in adaptation and indicate the potential mis-inference when they are neglected in fitness landscape studies.

New Evolutionary Theory Via Simulation

2021 ◽  
pp. 75-96
Author(s):  
Gino Cattani ◽  
Mariano Mastrogiorgio
Keyword(s):  
Technological Innovation ◽  
Evolutionary Theory ◽  
Fitness Landscape ◽  
Simulation Modelling ◽  
Fitness Landscapes ◽  
Number Of Components ◽  
Nk Model ◽  
Technological Adaptation ◽  
Nk Landscapes ◽  
History Friendly Models

Simulation modelling is very common in evolutionary approaches to economics, strategy, and technological innovation. A well-established simulation framework is the NK model of fitness landscapes, which is particularly useful for modelling the processes of technological adaptation, whose difficulty is reflected into how a fitness landscape behaves as a function of the number of components and internal interdependencies of a technology. However, classical NK models become problematic when modelling different types of processes, such as technological exaptation, unless a broader family of NK models is considered. After reviewing the classical NK model, this chapter explores the potential of ‘generalized’ NK landscapes, followed by a review of other important simulation frameworks in evolutionary theory, such as holey landscapes, quantum-like approaches, and history-friendly models.

The Relationship Between Suicidal Thinking and Dating Violence in a Sample of Adolescent Abortion Patients

Crisis ◽  
2011 ◽  
Vol 32 (5) ◽  
pp. 246-253 ◽  
Author(s):  
Gretchen E. Ely ◽  
William R. Nugent ◽  
Julie Cerel ◽  
Mholi Vimbba
Keyword(s):  
Unintended Pregnancy ◽  
Dating Violence ◽  
Young Women ◽  
Psychosocial Problems ◽  
The Other ◽  
Assessment Scale ◽  
Adolescent Dating Violence ◽  
Adolescent Relationships ◽  
Suicidal Thinking ◽  
The Relationship

Background: The relationship between suicidal thinking and adolescent dating violence has not been previously explored in a sample of adolescent abortion patients. Aims: This paper highlights a study where the relationship between dating violence and severity of suicidal thinking was examined in a sample of 120 young women ages 14–21 seeking to terminate an unintended pregnancy. Methods: The Multidimensional Adolescent Assessment Scale and the Conflict in Adolescent Relationships Scale was used to gather information about psychosocial problems and dating violence so that the relationship between the two problems could be examined, while controlling for the other psychosocial problems. Results: The results suggest that dating violence was related to severity of suicidal thinking, and that the magnitude of this relationship was moderated by the severity of problems with aggression. Conclusions: Specifically, as the severity of participant’s general problems with aggression increased, the magnitude of the relationship between dating violence and severity of suicidal thinking increased. Limitations of the study and implications for practice are discussed.

Emotional Impact Feedback Changes How We Remember Negative Autobiographical Experiences

2010 ◽  
Vol 57 (5) ◽  
pp. 354-359 ◽  
Author(s):  
Melanie K. T. Takarangi ◽  
Deryn Strange
Keyword(s):  
Well Being ◽  
The Other ◽  
Personal Perspective ◽  
Emotional Impact ◽  
Potential Mechanism ◽  
Negative Experiences ◽  
Negative Memory ◽  
The Relationship ◽  
Negative Memories ◽  
Over Time

When people are told that their negative memories are worse than other people’s, do they later remember those events differently? We asked participants to recall a recent negative memory then, 24 h later, we gave some participants feedback about the emotional impact of their event – stating it was more or less negative compared to other people’s experiences. One week later, participants recalled the event again. We predicted that if feedback affected how participants remembered their negative experiences, their ratings of the memory’s characteristics should change over time. That is, when participants are told that their negative event is extremely negative, their memories should be more vivid, recollected strongly, and remembered from a personal perspective, compared to participants in the other conditions. Our results provide support for this hypothesis. We suggest that external feedback might be a potential mechanism in the relationship between negative memories and psychological well-being.

Haematocrit: Relationships with Blood Lipids, Blood Pressure and other Cardiovascular Risk Factors

1994 ◽  
Vol 72 (01) ◽  
pp. 058-064 ◽  
Author(s):  
Goya Wannamethee ◽  
A Gerald Shaper
Keyword(s):  
Physical Activity ◽  
Risk Factors ◽  
Blood Pressure ◽  
Body Mass Index ◽  
Cardiovascular Risk ◽  
Cardiovascular Risk Factors ◽  
Alcohol Intake ◽  
Blood Lipids ◽  
The Other ◽  
The Relationship

SummaryThe relationship between haematocrit and cardiovascular risk factors, particularly blood pressure and blood lipids, has been examined in detail in a large prospective study of 7735 middle-aged men drawn from general practices in 24 British towns. The analyses are restricted to the 5494 men free of any evidence of ischaemic heart disease at screening.Smoking, body mass index, physical activity, alcohol intake and lung function (FEV1) were factors strongly associated with haematocrit levels independent of each other. Age showed a significant but small independent association with haematocrit. Non-manual workers had slightly higher haematocrit levels than manual workers; this difference increased considerably and became significant after adjustment for the other risk factors. Diabetics showed significantly lower levels of haematocrit than non-diabetics. In the univariate analysis, haematocrit was significantly associated with total serum protein (r = 0*18), cholesterol (r = 0.16), triglyceride (r = 0.15), diastolic blood pressure (r = 0.17) and heart rate (r = 0.14); all at p <0.0001. A weaker but significant association was seen with systolic blood pressure (r = 0.09, p <0.001). These relationships remained significant even after adjustment for age, smoking, body mass index, physical activity, alcohol intake, lung function, presence of diabetes, social class and for each of the other biological variables; the relationship with systolic blood pressure was considerably weakened. No association was seen with blood glucose and HDL-cholesterol. This study has shown significant associations between several lifestyle characteristics and the haematocrit and supports the findings of a significant relationship between the haematocrit and blood lipids and blood pressure. It emphasises the role of the haematocrit in assessing the risk of ischaemic heart disease and stroke in individuals, and the need to take haematocrit levels into account in determining the importance of other cardiovascular risk factors.

Structuralism as a Pamphlet (On the Book by E. Reinert “How Rich CountriesGot Rich... And Why Poor Countries Stay Poor”. 2nd ed.)

2014 ◽  
pp. 147-153
Author(s):  
P. Orekhovsky
Keyword(s):  
Economic Theory ◽  
Economic Development ◽  
Structural Analysis ◽  
Increasing Returns ◽  
The Other ◽  
Static Theory ◽  
Poor Countries ◽  
Historical School ◽  
Socio Economic Development ◽  
The Relationship

The review outlines the connection between E. Reinert’s book and the tradition of structural analysis. The latter allows for the heterogeneity of industries and sectors of the economy, as well as for the effects of increasing and decreasing returns. Unlike the static theory of international trade inherited from the Ricardian analysis of comparative advantage, this approach helps identify the relationship between trade, production, income and population growth. Reinert rehabilitates the “other canon” of economic theory associated with the mercantilist tradition, F. Liszt and the German historical school, as well as a reconside ration of A. Marshall’s analysis of increasing returns. Empirical illustrations given in the book reveal clear parallels with the path of Russian socio-economic development in the last twenty years.

Dış Göç Romanlarında Temel İzlekler

2020 ◽  
Vol 7 (2) ◽  
pp. 291-317
Author(s):  
Burak Çavuş
Keyword(s):  
The Other ◽  
Guest Worker ◽  
Migration Literature ◽  
Historical Reality ◽  
Literary Process ◽  
The Relationship

Bu çalışmada, 1960-1990 yılları arasında yayınlanan ve Avrupa’ya işçi göçünü konu edinen romanlar izleksel bağlamda incelenmiştir. Romanlardaki temel izlekler çerçevesinde göç süreci irdelenmiş, inceleme, göçmenlerin tanımlanmasında ve adlandırılmasında kullanılan Gastarbeiter (konuk işçi) Auslander (yabancı) kavramları ve Almanlar tarafından Türk kimliğine atfedilen çağrışımlar üzerinden yürütülmüştür. Göçmenlere yönelik politikalarda ve yaklaşımlarda onların nasıl tanımlandığının etkili olduğuna ve yazınsal süreçte de bu politika ve yaklaşımların belirleyici olduğu savından hareket edilmiştir. Bu noktada adlandırmaların, tanımlamaların göç olayı çerçevesinde biz ve öteki ilişkisi üzerindeki etkisine odaklanılmış; toplum ve yazın ilişkisi temelinde incelenen romanlar üzerinden göç ve göçmenlik meselesine dair çıkarımlar yapılmıştır. Bunlar arasında, ayrımcılık, kötü çalışma koşulları, hak ihlalleri, ırkçılık ve ötekileştirme gibi başat sorunların bu eserlerde merkezi konumda olduğu tespit edilmiştir. Böylece çalışmanın amacı olan göç yazınını oluşturan temel izleklere ulaşılmış; sosyolojik ve tarihsel gerçekliğin yazınsal gerçekliğe aktarılmasında etkili olan unsurlar ön plana çıkarılmıştır. ABSTRACT IN ENGLISH Main Patterns in Migration Novels In this study, the novels published between 1960-1990 and dealing with the migration of workers to Europe were examined in a contextual context. The process of immigration has been examined within the framework of the basic lines in the novels, through the concepts of Gastarbeiter (guest worker), Auslander (foreigner) used in the identification and naming of immigrants and connotations attributed to Turkish identity was conducted. The argument is that how they are defined is effective in policies and approaches towards immigrants and that these policies and approaches are determinative in the literary process. At this point, the effect of naming definitions on us and the other relationship within the framework of migration has been focused; there are inferences about the issue of migration and immigration through the novels examined on the basis of the relationship between society and literature. Among these, it has been determined that dominant problems such as discrimination, poor working violations, racism and marginalization are central to these works. Thus, the basic themes that constitute the migration literature, which is the aim of the study have been reached and the factors that are effective in transferring the sociological and historical reality have been brought the fore.

“I’ve got you under my skin”: borderline states in couple relationships

2020 ◽  
Vol 10 (1) ◽  
pp. 59-71
Author(s):  
Perrine Moran
Keyword(s):  
The Other ◽  
Couple Relationships ◽  
Early Stages ◽  
Popular Songs ◽  
The Relationship

Many couples who come for therapy are struggling with separating from unconscious phantasies and beliefs that enmesh each partner with the other, resulting in states that popular songs powerfully epitomise. While this borderline experience is common and functional in the early stages of being in love its persistence paralyses the development of the relationship. Facing separation from and loss of illusion is a challenge couple therapists are often asked to help with. The argument is illustrated by a case, and by references to some of Cole Porter’s best known songs.

From Container to Claustrum: Projective Identification in Couples

2014 ◽  
Vol 4 (2) ◽  
Author(s):  
Tamara Feldman
Keyword(s):  
Psychological Health ◽  
Projective Identification ◽  
The Self ◽  
The Other ◽  
Intimate Partners ◽  
And Control ◽  
The Relationship ◽  
As If

This paper is a contribution to the growing literature on the role of projective identification in understanding couples' dynamics. Projective identification as a defence is well suited to couples, as intimate partners provide an ideal location to deposit unwanted parts of the self. This paper illustrates how projective identification functions differently depending on the psychological health of the couple. It elucidates how healthier couples use projective identification more as a form of communication, whereas disturbed couples are inclined to employ it to invade and control the other, as captured by Meltzer's concept of "intrusive identification". These different uses of projective identification affect couples' capacities to provide what Bion called "containment". In disturbed couples, partners serve as what Meltzer termed "claustrums" whereby projections are not contained, but imprisoned or entombed in the other. Applying the concept of claustrum helps illuminate common feelings these couples express, such as feeling suffocated, stifled, trapped, held hostage, or feeling as if the relationship is killing them. Finally, this paper presents treatment challenges in working with more disturbed couples.

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