Adaptive Divergence

Eco-evolutionary Dynamics ◽

10.23943/princeton/9780691145433.003.0004 ◽

2016 ◽

Author(s):

Andrew P. Hendry

Keyword(s):

Sexual Selection ◽

Empirical Data ◽

Convergent Evolution ◽

Adaptive Landscape ◽

Adaptive Divergence ◽

Single Population ◽

Adaptive Landscapes ◽

Different Populations ◽

Key Questions

This chapter analyzes how the adaptive landscape concept can be extended from a single population in a single environment to multiple populations in multiple environments. Specifically, different environments produce different fitness peaks and divergent selection then drives different populations toward those different peaks. The chapter outlines methods for inferring adaptive divergence with respect to both phenotypes and fitness. It then turns to a review of empirical data informing several key questions about adaptive divergence in nature, including how prevalent and strong it is, how many peaks adaptive landscapes have, how predictable it is (parallel and convergent evolution), and what the role of sexual selection is in modifying adaptive divergence.

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Peak shifts and extinction under sex-specific selection

10.1101/2021.02.18.431780 ◽

2021 ◽

Author(s):

Stephen P. De Lisle

Keyword(s):

Sexual Selection ◽

Sexual Dimorphism ◽

Peak Shift ◽

Adaptive Landscape ◽

Population Estimates ◽

Sexual Antagonism ◽

Adaptive Landscapes ◽

Quantitative Genetic ◽

Complex Adaptive ◽

The Face

AbstractA well-known property of sexual selection combined with a cross sex genetic correlation (rmf), is that it can facilitate a peak shift on the adaptive landscape. How do these diversifying effects of sexual selection +rmf balance with the constraints imposed by such sexual antagonism, to affect macroevolution of sexual dimorphism? Here, I extend existing quantitative genetic models of evolution on complex adaptive landscapes. Beyond recovering classical predictions for the conditions promoting a peak shift, I show that when rmf is moderate to strong, relatively weak sexual selection is required to induce a peak shift in males only. Increasing the strength of sexual leads to a sexually-concordant peak shift, suggesting that macroevolutionary rates of sexual dimorphism may be largely decoupled from the strength of within-population sexual selection. Accounting explicitly for demography further reveals that sex-specific peak shifts may be more likely to be successful than concordant shifts in the face of extinction, especially when natural selection is strong. An overarching conclusion is that macroevolutionary patterns of sexual dimorphism are unlikely to be readily explained by within-population estimates of selection or constraint alone.

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Peak shifts and extinction under sex-specific selection

Biology Letters ◽

10.1098/rsbl.2021.0278 ◽

2021 ◽

Vol 17 (10) ◽

Author(s):

Stephen P. De Lisle

Keyword(s):

Sexual Selection ◽

Sexual Dimorphism ◽

Peak Shift ◽

Adaptive Landscape ◽

Population Estimates ◽

Sexual Antagonism ◽

Adaptive Landscapes ◽

Quantitative Genetic ◽

Complex Adaptive ◽

The Face

A well-known property of sexual selection combined with a cross-sex genetic correlation ( r mf ) is that it can facilitate a peak shift on the adaptive landscape. How do these diversifying effects of sexual selection + r mf balance with the constraints imposed by such sexual antagonism, to affect the macroevolution of sexual dimorphism? Here, I extend existing quantitative genetic models of evolution on complex adaptive landscapes. Beyond recovering classical predictions for the conditions promoting a peak shift, I show that when r mf is moderate to strong, relatively weak sexual selection is required to induce a peak shift in males only. Increasing the strength of sexual selection leads to a sexually concordant peak shift, suggesting that macroevolutionary rates of sexual dimorphism may be largely decoupled from the strength of within-population sexual selection. Accounting explicitly for demography further reveals that sex-specific peak shifts may be more likely to be successful than concordant shifts in the face of extinction, especially when natural selection is strong. An overarching conclusion is that macroevolutionary patterns of sexual dimorphism are unlikely to be readily explained by within-population estimates of selection or constraint alone.

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The Role of Vitamin D as a Biomarker in Alzheimer’s Disease

Brain Sciences ◽

10.3390/brainsci11030334 ◽

2021 ◽

Vol 11 (3) ◽

pp. 334

Author(s):

Giulia Bivona ◽

Bruna Lo Sasso ◽

Caterina Maria Gambino ◽

Rosaria Vincenza Giglio ◽

Concetta Scazzone ◽

...

Keyword(s):

Vitamin D ◽

Risk Factor ◽

Cognitive Decline ◽

Immune Cell ◽

Response To Treatment ◽

Cellular Processes ◽

Vitamin D Levels ◽

The Brain ◽

Key Questions

Vitamin D and cognition is a popular association, which led to a remarkable body of literature data in the past 50 years. The brain can synthesize, catabolize, and receive Vitamin D, which has been proved to regulate many cellular processes in neurons and microglia. Vitamin D helps synaptic plasticity and neurotransmission in dopaminergic neural circuits and exerts anti-inflammatory and neuroprotective activities within the brain by reducing the synthesis of pro-inflammatory cytokines and the oxidative stress load. Further, Vitamin D action in the brain has been related to the clearance of amyloid plaques, which represent a feature of Alzheimer Disease (AD), by the immune cell. Based on these considerations, many studies have investigated the role of circulating Vitamin D levels in patients affected by a cognitive decline to assess Vitamin D’s eventual role as a biomarker or a risk factor in AD. An association between low Vitamin D levels and the onset and progression of AD has been reported, and some interventional studies to evaluate the role of Vitamin D in preventing AD onset have been performed. However, many pitfalls affected the studies available, including substantial discrepancies in the methods used and the lack of standardized data. Despite many studies, it remains unclear whether Vitamin D can have a role in cognitive decline and AD. This narrative review aims to answer two key questions: whether Vitamin D can be used as a reliable tool for diagnosing, predicting prognosis and response to treatment in AD patients, and whether it is a modifiable risk factor for preventing AD onset.

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Transnational Lived Citizenship – The Case of the Eritrean Diaspora

Africa Spectrum ◽

10.1177/00020397211005472 ◽

2021 ◽

Vol 56 (1) ◽

pp. 3-18

Author(s):

Tanja R. Müller ◽

Milena Belloni

Keyword(s):

The State ◽

Special Focus ◽

Diaspora Studies ◽

Historical Events ◽

Everyday Practices ◽

Key Questions

This special focus section analyses state–diaspora relationships with a focus on the case of Eritrea, a paradigmatic example, as we show in this introduction, to elaborate on the following key questions: What determines loyalty between diaspora and the state? How can we understand the dynamics of co-optation, loyalty, and resistance that characterise many diaspora–state relationships? What is the role of historical events and memory in building alliances as well as divides among different generations and different groups in the diaspora? How do diaspora citizens interpret and enact their citizenship in everyday practices of engagement? By engaging with both citizenship and diaspora studies, this introduction shows the significance of analysing these questions through the lens of “transnational lived citizenship.” This concept enables a look at the intersections between formal aspects of citizenship as well as the emotional and practical aspects related to feelings of belonging, transnational attitudes, and circulation of material cultures.

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Maximum fluid concentrations of materials released from platelets at a surface

AJP Heart and Circulatory Physiology ◽

10.1152/ajpheart.1983.244.1.h109 ◽

1983 ◽

Vol 244 (1) ◽

pp. H109-H114 ◽

Cited By ~ 3

Author(s):

G. A. Adams ◽

I. A. Feuerstein

Keyword(s):

Platelet Aggregation ◽

Empirical Data ◽

Maximum Amount ◽

Inhibit Platelet Aggregation ◽

Fluid Concentration ◽

Diffusion And Convection ◽

Platelet Accumulation ◽

Von Willebrand ◽

Willebrand Factor

We examine the estimation of local concentrations of materials that are released from the dense and alpha-granules of platelets during accumulation of platelets upon collagen-coated glass. Platelet/red blood cell suspensions were perfused through a 1.3-mm-ID tube. Empirical data were used in a calculation procedure, based on diffusion and convection, designed to yield an upper bound on the interfacial fluid concentration (IFC) for each substance considered. The necessary empirical data are the rate of platelet accumulation and the maximum amount of material in the platelet capable of secretion. It was found that the IFC is dependent on the shear rate at the surface (G) and is proportional to G0.27. This means that an eightfold increase in flow rate would increase the IFCs approximately twofold. Serotonin, pyrophosphate, adenosine 5'-monophosphate (AMP), and adenosine 5'-triphosphate (ATP) were found not to be present in sufficient quantities to produce IFCs that could influence platelet aggregation if used alone at the IFC. A second set of materials, fibrinogen, fibronectin von Willebrand factor, and calcium, had IFCs less than their concentrations normally found in plasma. A third category, containing adenosine 5'-diphosphate (ADP) alone, had an IFC close to those known to affect platelet aggregation. The role of metabolites of arachidonic acid, which may promote or inhibit platelet aggregation, awaits further description.

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The Role of Radio Loud Phase of Nuclear Activity in Galaxy Formation and Evolution

Proceedings of the International Astronomical Union ◽

10.1017/s1743921314004487 ◽

2013 ◽

Vol 9 (S304) ◽

pp. 419-420

Author(s):

Gabriel A. Ohanian

Keyword(s):

Galaxy Formation ◽

Subsequent Development ◽

Nuclear Activity ◽

Evolution Of Galaxies ◽

Galaxy Formation And Evolution ◽

Formation And Evolution ◽

Key Questions

AbstractKey questions, which arise when one tries to clear up a problem of formation and evolution of galaxies, is the question of energy: what is the energetic budget of AGN owing to form galaxies and provide its subsequent development? Hence, for understanding the formation and evolution of galaxies, it is important to estimate the energetic budget of AGN which we try to do involving radio loud phase of nuclear activity.

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A nudge in the right direction: the role of food choice architecture in changing populations' diets

Proceedings of The Nutrition Society ◽

10.1017/s0029665120007983 ◽

2021 ◽

pp. 1-12

Author(s):

H. Ensaff

Keyword(s):

Food Choice ◽

Empirical Studies ◽

Food Selection ◽

Theoretical Background ◽

Choice Architecture ◽

Different Populations ◽

The Right ◽

Care Costs

Populations' diets typically fall short of recommendations. The implication of this on ill health and quality of life is well established, as are the subsequent health care costs. An area of growing interest within public health nutrition is food choice architecture; how a food choice is framed and its influence on subsequent food selection. In particular, there is an appeal to manipulating the choice architecture in order to nudge individuals' food choice. This review outlines the current understanding of food choice architecture, theoretical background to nudging and the evidence on the effectiveness of nudge strategies, as well as their design and implementation. Interventions emphasising the role of nudge strategies have investigated changes to the accessibility, availability and presentation of food and the use of prompts. Empirical studies have been conducted in laboratories, online and in real-world food settings, and with different populations. Evidence on the effectiveness of nudge strategies in shifting food choice is encouraging. Underpinning mechanisms, not yet fully explicated, are proposed to relate to salience, social norms and the principle of least effort. Emerging evidence points to areas for development including the effectiveness of choice architecture interventions with different and diverse populations, and the combined effect of multiple nudges. This, alongside further examination of theoretical mechanisms and guidance to engage and inspire across the breadth of food provision, is critical. In this way, the potential of choice architecture to effect meaningful change in populations' diets will be realised.

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Thomas Aquinas and Contemplation

10.1093/oso/9780192895295.001.0001 ◽

2021 ◽

Author(s):

Rik Van Nieuwenhove

Keyword(s):

Holy Spirit ◽

Thomas Aquinas ◽

Central Importance ◽

Marked Contrast ◽

Faith And Reason ◽

Beatific Vision ◽

The Holy Spirit ◽

Theology And Philosophy ◽

Key Questions

Contemplation, according to Thomas Aquinas, is the central goal of our life; yet a scholarly study on this topic has not appeared for over seventy years. This book fills that obvious gap. From an interdisciplinary perspective this study considers the epistemological and metaphysical foundations of the contemplative act; the nature of the active and contemplative lives in light of Aquinas’s Dominican calling; the role of faith, charity, and the gifts of the Holy Spirit in contemplation; and contemplation and the beatific vision. Key questions addressed are: What is contemplation? What is truth? How can we know God? How do faith and reason relate to one another? How does Aquinas envisage the relations between theology and philosophy? What role does charity play in contemplation? Throughout this book the author argues that Aquinas espouses a profoundly intellective notion of contemplation in the strictly speculative sense, which culminates in a non-discursive moment of insight (intuitus simplex). In marked contrast to his contemporaries Aquinas therefore rejects a sapiential or affective brand of theology. He also employs a broader notion of contemplation, which can be enjoyed by all Christians, in which the gifts of the Holy Spirit are of central importance. This book should appeal to all those who are interested in this key aspect of Aquinas’s thought. It provides a lucid account of central aspects of Aquinas’s metaphysics, epistemology, theology, and spirituality. It also offers new insights into the nature of the theological discipline as Aquinas sees it, and how theology relates to philosophy.

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A Study on the Prevalence and Nature of Ragging Practices in Selected Educational Institutions in India

Contemporary Education Dialogue ◽

10.1177/0973184918781213 ◽

2018 ◽

Vol 15 (2) ◽

pp. 187-202

Author(s):

Mohan Rao ◽

Shobna Sonpar ◽

Amit Sen ◽

Shekhar P. Seshadri ◽

Harsh Agarwal ◽

...

Keyword(s):

Empirical Data ◽

Print Media ◽

Institutional Factors ◽

Educational Institutions ◽

Critical Factors ◽

Place Of Residence ◽

The Media ◽

Media Reports

Ragging has claimed hundreds of innocent lives and has ruined the careers of thousands of students. A total of 717 cases of ragging were reported in the English print media alone across the country from January 2007 to September 2013. However, the media reports tend to focus on extreme cases and do not reveal the true extent of ragging. Moreover, in the absence of empirical data, it is difficult to understand the processes involved in, and the ramifications of, ragging. This study examines the prevalence and types of ragging practices in educational institutions. The study covered 10,632 students from 37 educational institutions spread across 12 states in India. Findings show that almost 40 per cent students admitted to having experienced some kind of ragging. College-wise analysis of the results showed marked variations in the prevalence of ragging among colleges, thus pointing to the role of institutional factors in the occurrence of ragging. Variations in responses are also seen based on the kind of course pursued, gender, and place of residence of student, thus indicating that these are critical factors in influencing the prevalence, severity and kinds of ragging practices.

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