genetical theory of kin selection GARDNER, A; WEST, S.A; WILD, G
Journal of evolutionary biology,
20/May , Letnik:
24, Številka:
5
Journal Article
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Natural selection operates both directly, via the impact of a trait upon the individual's own fitness, and indirectly, via the impact of the trait upon the fitness of the individual's genetically ...related social partners. These effects are often framed in terms of Hamilton's rule, rb − c > 0, which provides the central result of social-evolution theory. However, a number of studies have questioned the generality of Hamilton's rule, suggesting that it requires restrictive assumptions. Here, we use Fisher's genetical paradigm to demonstrate the generality of Hamilton's rule and to clarify links between different studies. We show that confusion has arisen owing to researchers misidentifying model parameters with the b and c terms in Hamilton's rule, and misidentifying measures of genotypic similarity or genealogical relationship with the coefficient of genetic relatedness, r. More generally, we emphasize the need to distinguish between general kin-selection theory that forms the foundations of social evolution, and streamlined kin-selection methodology that is used to solve specific problems.
Hearing impairment is a growing physical disability affecting older adults and is an important physical health stressor, but few studies have examined it in relation to mental health outcomes and ...even fewer have considered the role of social support in buffering this relationship. The current study builds on the stress process framework and uses longitudinal data from three waves of the Health and Retirement Study (2006, 2010, 2014) to examine the relationship between hearing impairment and depressive symptoms among U.S. adults aged 50 and older (n = 6075). The analysis uses fixed-effects models to assess this relationship and examine the extent to which social support mediates (buffers) or moderates (interaction) the association. The results found that worse self-rated hearing was associated with a significant increase in depressive symptoms, even after controlling for sociodemographic factors. Social support did not buffer this relationship. Instead, social support interacted with hearing impairment: low levels of social support were associated with more depressive symptoms but only among people with poor self-rated hearing. Among those with excellent self-rated hearing, low levels of social support did not increase depressive symptoms. Moreover, high levels of social support reduced depressive symptoms for those with poor hearing. These findings suggest that hearing impairment is a chronic stressor in individuals' lives, and that responses to this stressor vary by the availability of social resources.
•Research on the relationship between hearing impairment and depressive symptoms is mixed.•Hearing impairment is a physical health stressor that can affect mental health outcomes.•The relationship between hearing impairment and depressive symptoms differs by levels of social support.•People with hearing impairment with high levels of social support are protected against an increase in depressive symptoms.•Improvements in social support for people with hearing impairment may protect against negative mental health impacts.
The carbon-carbon (C-C) bond cleavage of cyclopropanols is a wide area of research with much current activity. This review highlights new developments in this area over the past two decades. A ...summary is made of the three main reactivity modes, namely, homoenolate chemistry, β-keto radical chemistry, and acid-catalyzed ring-opening, as well as all other methods for the C-C bond cleavage and functionalization of cyclopropanols, including base-mediated ring-opening, metal-catalyzed C-C insertions and eliminations, oxidative fragmentation using hypervalent iodine reagents, reactions of donor-acceptor cyclopropanols, and pericylic reactions. Emphasis is placed on the synthetic utility of cyclopropanols and related derivatives, which have emerged as unique three-carbon synthons.
From an evolutionary perspective, social behaviours are those which have fitness consequences for both the individual that performs the behaviour, and another individual. Over the last 43 years, a ...huge theoretical and empirical literature has developed on this topic. However, progress is often hindered by poor communication between scientists, with different people using the same term to mean different things, or different terms to mean the same thing. This can obscure what is biologically important, and what is not. The potential for such semantic confusion is greatest with interdisciplinary research. Our aim here is to address issues of semantic confusion that have arisen with research on the problem of cooperation. In particular, we: (i) discuss confusion over the terms kin selection, mutualism, mutual benefit, cooperation, altruism, reciprocal altruism, weak altruism, altruistic punishment, strong reciprocity, group selection and direct fitness; (ii) emphasize the need to distinguish between proximate (mechanism) and ultimate (survival value) explanations of behaviours. We draw examples from all areas, but especially recent work on humans and microbes.
This article imagines abolitionist politics in the Yucatán peninsula as one group, known as U jeets'el le ki'ki’ kuxtal, pushes against one portion of Mexican president Andrés Manuel López Obrador's ...development plan known as the “Tren Maya.” I contend that U je'etsel's calls for autonomy speak to forms of radical abolitionist politics present in the United States, where we might observe the centrality of land in both abolition and decolonization. To this end, I first provide a definition of a trans feminist abolition radically focused on the otherwise, or the eradication of all forms of social oppression. This definition is followed by close readings of U je'etsel's communiqués regarding AMLO's 2021 visit to the Yucatán peninsula and the continued role the so‐called “Caste War” plays in attempts to expand nationalized colonization into the region. My final goal is to proffer that “Caste War” constitutes a historicized form of radical autonomy as well as project of abolition subject to forces that seek to vacate it of its liberatory power. I demonstrate that part of U je'etsel's discursive project is to reclaim the “Caste War” narrative as part of an emancipatory project involving a radical reclaiming of autonomy's regional history.
Contex Chronic stress presents a growing, pervasive burden in healthcare, and mobile smartphone applications (apps) have the potential to deliver evidence-based stress management strategies. This ...review identified and evaluated stress management apps across domains of (1) evidence-based content; (2) transparency in app development; and (3) functionality of the app interface. Evidence acquisition The iOS App Store was systematically searched. Apps with descriptions indicating that they targeted the intended audience and included evidence-related terminology, at least one evidence-based stress management strategy, and behavior change components were downloaded and evaluated by two independent raters across the three domains of evidence-based content, transparency, and functionality. Evidence synthesis A total of 902 apps were identified based on 21 searches. Of these, 60 met study criteria and were downloaded and evaluated between April and June 2015. Twenty (33%) ultimately did not deliver an evidence-based strategy. Of the delivered strategies, the most common were mindfulness and meditation (73%) and diaphragmatic breathing (25%). On average, apps addressed half of the transparency criteria, and nearly all (85%) were acceptable across usability criteria. A total of 32 apps included both evidence-based content and exhibited no problems with usability or functionality; apps affiliated with a non-profit, research-engaged institution comprised 31% of these. Conclusions This review evaluated 60 iOS apps for stress management across domains of evidence-based content, transparency, and functionality; these apps have the potential to effectively supplement medical care. Findings further indicate that a comprehensive, multi-domain approach can distinguish apps that use evidence-based strategies from those that do not.
The Wet Chemistry Laboratory on the Phoenix Mars Lander performed aqueous chemical analyses of martian soil from the polygon-patterned northern plains of the Vastitas Borealis. The solutions ...contained approximately 10 mM of dissolved salts with 0.4 to 0.6% perchlorate (ClO₄) by mass leached from each sample. The remaining anions included small concentrations of chloride, bicarbonate, and possibly sulfate. Cations were dominated by Mg²⁺ and Na⁺, with small contributions from K⁺ and Ca²⁺. A moderately alkaline pH of 7.7 ± 0.5 was measured, consistent with a carbonate-buffered solution. Samples analyzed from the surface and the excavated boundary of the approximately 5-centimeter-deep ice table showed no significant difference in soluble chemistry.
Molecular Cell talks with corresponding authors Steven West and Torben Heick Jensen about the journey toward back-to-back publication of their recent Molecular Cell papers, and they share their ...advice for coordinating the steps along the way.
A key step in the evolution of multicellular organisms is the formation of cooperative multicellular groups. It has been suggested that predation pressure may promote multicellular group formation in ...some algae and bacteria, with cells forming groups to lower their chance of being eaten. We use the green alga Chlorella vulgaris and the protist Tetrahymena thermophila to test whether predation pressure can initiate the formation of colonies. We found that: (1) either predators or just predator exoproducts promote colony formation; (2) higher predator densities cause more colonies to form; and (3) colony formation in this system is facultative, with populations returning to being unicellular when the predation pressure is removed. These results provide empirical support for the hypothesis that predation pressure promotes multicellular group formation. The speed of the reversion of populations to unicellularity suggests that this response is due to phenotypic plasticity and not evolutionary change.
The purpose of this study was to investigate the influence that replacing natural coarse aggregate with recycled concrete aggregate (RCA) has on concrete bond strength with reinforcing steel. Two ...sources of RCA were used along with one natural aggregate source. Numerous aggregate properties were measured for all aggregate sources. Two types of concrete mixture proportions were developed replacing 100% of the natural aggregate with RCA. The first type maintained the same water–cement ratios while the second type was designed to achieve the same compressive strengths. Beam-end specimens were tested to determine the relative bond strength of RCA and natural aggregate concrete. On average, natural aggregate concrete specimens had bond strengths that were 9 to 19% higher than the equivalent RCA specimens. Bond strength and the aggregate crushing value seemed to correlate well for all concrete types.
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