scholarly journals Shift-inducible [transgenerational] increase in recombination rate as an evolving strategy in a periodic environment: a numerical model

2021 ◽  
Author(s):  
Sviatoslav Rybnikov ◽  
Sariel Hübner ◽  
Abraham Korol
Keyword(s):  
Recombination Rate ◽  
Physiological Stress ◽  
Empirical Studies ◽  
Theoretical Models ◽  
Epigenetic Factors ◽  
Periodic Environment ◽  
Evolutionary Advantage ◽  
Plastic Changes ◽  
Optimal Recombination ◽  
Evolutionary Role

Numerous empirical studies have witnessed a plastic increase in meiotic recombination rate in organisms experiencing physiological stress due to unfavourable environmental conditions. Yet, it is not clear enough which characteristics of an ecological factor (intensity, duration, variability, etc.) make it stressogenic and therefore recombinogenic for an organism. Several previous theoretical models proceeded from the assumption that organisms increase their recombination rate when the environment becomes more severe, and demonstrated the evolutionary advantage of such recombination strategy. Here we explore another stress-associated recombination strategy, implying a reversible increase in recombination rate each time when the environment alternates. We allow such plastic changes in the organisms, grown in an environment different from that of their parents, and, optionally, also in their offspring. We show that such shift-inducible recombination is always favoured over intermediate constant optimal recombination. Besides, it sometimes outcompetes also zero and free optimal constant recombination, therefore making selection on recombination less polarized. Shift-inducible strategies with a longer, transgenerational plastic effect, are favoured under slightly stronger selection and longer period. These results hold for both panmixia and partial selfing, although selfing makes the dynamics of recombination modifier alleles faster. Our results suggest that epigenetic factors, presumably underlying the environmental plasticity of recombination, may play an important evolutionary role.

scholarly journals The evolutionary advantage of condition-dependent recombination in a Red Queen model with diploid antagonists

2018 ◽  
Author(s):  
Sviatoslav R. Rybnikov ◽  
Zeev M. Frenkel ◽  
Tzion Fahima ◽  
Abraham B. Korol
Keyword(s):  
Recombination Rate ◽  
Theoretical Models ◽  
Condition Dependence ◽  
Red Queen ◽  
Recombination Rates ◽  
Optimal Constant ◽  
Evolutionary Advantage ◽  
Mean Fitness ◽  
Parameter Values ◽  
Red Queen Model

AbstractAntagonistic interaction, like those between a host and its parasite, are known to cause oscillations in genetic structure of both species, usually referred to as Red Queen dynamics (RQD). The RQD is believed to be a plausible explanation for the evolution of sex/recombination, although numerous theoretical models showed that this may happen only under rather restricted parameter values (selection intensity, epistasis, etc.). Here, we consider two diploid antagonists, each with either two or three selected loci; the interaction is based on matching phenotypes model. We use the RQD, whenever it emerges in this system, as a substrate to examine the evolution of one recombination feature, condition dependence in diploids, which still remains an underexplored question. We consider several forms of condition-dependent recombination, with recombination rates in the host being sensitive either to the parasite’s mean fitness, or to the host’s infection status, or to the host’s genotype fitness. We show that all form of condition-dependent recombination can be favored over the corresponding optimal constant recombination rate, even including situations in which the optimal constant recombination rate is zero.

scholarly journals Connecting theory and data to understand recombination rate evolution

2017 ◽  
Vol 372 (1736) ◽  
pp. 20160469 ◽  
Author(s):  
Amy L. Dapper ◽  
Bret A. Payseur
Keyword(s):  
Recombination Rate ◽  
Empirical Studies ◽  
Theoretical Work ◽  
Rate Variation ◽  
Recombination Rates ◽  
Theoretical Approaches ◽  
Evolutionary Advantage ◽  
New Directions ◽  
The Rich ◽  
Recombination Rate Variation

Meiotic recombination is necessary for successful gametogenesis in most sexually reproducing organisms and is a fundamental genomic parameter, influencing the efficacy of selection and the fate of new mutations. The molecular and evolutionary functions of recombination should impose strong selective constraints on the range of recombination rates. Yet, variation in recombination rate is observed on a variety of genomic and evolutionary scales. In the past decade, empirical studies have described variation in recombination rate within genomes, between individuals, between sexes, between populations and between species. At the same time, theoretical work has provided an increasingly detailed picture of the evolutionary advantages to recombination. Perhaps surprisingly, the causes of natural variation in recombination rate remain poorly understood. We argue that empirical and theoretical approaches to understand the evolution of recombination have proceeded largely independently of each other. Most models that address the evolution of recombination rate were created to explain the evolutionary advantage of recombination rather than quantitative differences in rate among individuals. Conversely, most empirical studies aim to describe variation in recombination rate, rather than to test evolutionary hypotheses. In this Perspective, we argue that efforts to integrate the rich bodies of empirical and theoretical work on recombination rate are crucial to moving this field forward. We provide new directions for the development of theory and the production of data that will jointly close this gap. This article is part of the themed issue ‘Evolutionary causes and consequences of recombination rate variation in sexual organisms’.

Emerging Syndromes

2017 ◽  
Author(s):  
Kelly C. Allison ◽  
Jennifer D. Lundgren
Keyword(s):  
Empirical Studies ◽  
Theoretical Models ◽  
Future Research ◽  
Night Eating Syndrome ◽  
Statistical Manual ◽  
Night Eating ◽  
Diagnostic And Statistical Manual ◽  
Impairment In Functioning ◽  
Atypical Anorexia Nervosa ◽  
Comorbid Psychopathology

The Diagnostic and Statistical Manual, fifth edition, of the American Psychiatric Association (2013) has designated several disorders under the diagnosis of otherwise specified feeding and eating disorder (OSFED). This chapter evaluates three of these, night eating syndrome (NES), purging disorder (PD), and atypical anorexia nervosa (atypical AN). It also reviews orthorexia nervosa, which has been discussed in the clinical realm as well as the popular press. The history and definition for each is reviewed, relevant theoretical models are presented and compared, and evidence for the usefulness of the models is described. Empirical studies examining the disorders’ independence from other disorders, comorbid psychopathology, and, when available, medical comorbidities, are discussed. Distress and impairment in functioning seem comparable between at least three of these emerging disorders and threshold eating disorders. Finally, remaining questions for future research are summarized.

scholarly journals A Systematic Review on Attachment and Sleep at Preschool Age

Children ◽  
2021 ◽  
Vol 8 (10) ◽  
pp. 895
Author(s):  
Catarina Perpétuo ◽  
Eva Diniz ◽  
Manuela Veríssimo
Keyword(s):  
Systematic Review ◽  
Attachment Security ◽  
Biological Process ◽  
Sleep Problems ◽  
Empirical Studies ◽  
Theoretical Models ◽  
Preschool Age ◽  
Future Research ◽  
Parent Child Relationships ◽  
Present Systematic Review

Sleep is a biological process that impacts nearly every domain of a child’s life. Sleep-wake regulation influences and it is highly influenced by developmental variables related to parent-child relationships, such as attachment. The main goal of the present systematic review is to analyze and integrate the findings of empirical studies investigating the relations between attachment and sleep in preschool age, a period marked by important developmental changes that challenge both attachment system and sleep-wake regulation. A database search was performed using a combination of relevant keywords, leading to the identification of 524 articles, with 19 manuscripts assessed for eligibility; finally, seven studies (2344 children) were included. Overall, the findings were not consistent, with some studies reporting significant associations between attachment security and sleep quality, as well as between attachment insecurity and sleep problems, whereas others did not find significant associations. The results are discussed in light of the available theoretical models and integrated in the context of measurement approaches to attachment and sleep heterogeneity, aiming to guide future research on the topic.

Research on capital structure determinants: a review and future directions

2017 ◽  
Vol 13 (2) ◽  
pp. 106-132 ◽  
Author(s):  
Satish Kumar ◽  
Sisira Colombage ◽  
Purnima Rao
Keyword(s):  
Capital Structure ◽  
Meta Analysis ◽  
Empirical Studies ◽  
Secondary Data ◽  
Theoretical Models ◽  
Order Theory ◽  
Organizational Level ◽  
Future Research ◽  
Content Type ◽  
The Impact

Purpose The purpose of this paper is to study the status of studies on capital structure determinants in the past 40 years. This paper highlights the major gaps in the literature on determinants of capital structure and also aims to raise specific questions for future research. Design/methodology/approach The prominence of research is assessed by studying the year of publication and region, level of economic development, firm size, data collection methods, data analysis techniques and theoretical models of capital structure from the selected papers. The review is based on 167 papers published from 1972 to 2013 in various peer-reviewed journals. The relationship of determinants of capital structure is analyzed with the help of meta-analysis. Findings Major findings show an increase of interest in research on determinants of capital structure of the firms located in emerging markets. However, it is observed that these regions are still under-examined which provides more scope for research both empirical and survey-based studies. Majority of research studies are conducted on large-sized firms by using secondary data and regression-based models for the analysis, whereas studies on small-sized firms are very meager. As majority of the research papers are written only at the organizational level, the impact of leverage on various industries is yet to be examined. The review highlights the major determinants of capital structure and their relationship with leverage. It also reveals the dominance of pecking order theory in explaining capital structure of firms theoretically as well as statistically. Originality/value The paper covers a considerable period of time (1972-2013). Among very few review papers on capital structure research, to the best of authors’ knowledge; this is the first review to identify what is missing in the literature on the determinants of capital structure while offering recommendations for future studies. It also synthesize the findings of empirical studies on determinants of capital structure statistically.

scholarly journals A meta-analysis of the quantitative studies in continuance intention to use an information system

2020 ◽  
Vol ahead-of-print (ahead-of-print) ◽  
Author(s):  
Frank Bivar Franque ◽  
Tiago Oliveira ◽  
Carlos Tam ◽  
Fernando de Oliveira Santini
Keyword(s):  
Information System ◽  
Meta Analysis ◽  
Empirical Studies ◽  
Theoretical Models ◽  
Temporal Analysis ◽  
Perceived Usefulness ◽  
Intention To Use ◽  
Continuance Intention ◽  
Content Type

PurposeThis study aims to describe, synthesise and clarify the findings of published studies on individual continuance intention to use an information system (IS), considering the fact that the number of studies in the continuance intention context are growing exponentially and cover several different subjects.Design/methodology/approachThe research uses meta- and weight analysis by taking 115 empirical studies from continuance intention to use an IS. The data are presented in different views using significant and non-significant relationships from all the studies. Furthermore, it uses hierarchical linear meta-analysis to analyse potential moderators that can influence continuance intention.FindingsThe results reveal that affective commitment, attitude, satisfaction, hedonic value and flow are the best predictors of continuance intention to use an IS. Sample size, individualism, uncertainty avoidance and long-term orientation moderate the relationship of perceived usefulness on continuance intention. Power distance, masculinity and indulgence moderate relationship satisfaction on continuance intention.Practical implicationsThe results reveal that continuance intention to use an IS has been studied in different countries, with different cultures; therefore, IS providers should have diversified managing strategies, to ensure the satisfaction of users and long-term usage of their IS.Originality/valueThe study provides a systematic overview of the most relevant variables used in the literature, including a temporal analysis of the theoretical models, highlighting the evolution of the constructs and presents a moderation analysis.

scholarly journals What drives the evolution of condition-dependent recombination in diploids? Some insights from simulation modelling

2017 ◽  
Vol 372 (1736) ◽  
pp. 20160460 ◽  
Author(s):  
Sviatoslav R. Rybnikov ◽  
Zeev M. Frenkel ◽  
Abraham B. Korol
Keyword(s):  
Recombination Rate ◽  
External Environment ◽  
Theoretical Models ◽  
Simulation Modelling ◽  
Condition Dependence ◽  
Rate Variation ◽  
Theoretical Studies ◽  
Recombination Rates ◽  
Modifier Locus ◽  
Recombination Rate Variation

While the evolutionary advantages of non-zero recombination rates have prompted diverse theoretical explanations, the evolution of essential recombination features remains underexplored. We focused on one such feature, the condition dependence of recombination, viewed as the variation in within-generation sensitivity of recombination to external (environment) and/or internal (genotype) conditions. Limited empirical evidence for its existence comes mainly from diploids, whereas theoretical models show that it only easily evolves in haploids. The evolution of condition-dependent recombination can be explained by its advantage for the selected system (indirect effect), or by benefits to modifier alleles, ensuring this strategy regardless of effects on the selected system (direct effect). We considered infinite panmictic populations of diploids exposed to a cyclical two-state environment. Each organism had three selected loci. Examining allele dynamics at a fourth, selectively neutral recombination modifier locus, we frequently observed that a modifier allele conferring condition-dependent recombination between the selected loci displaced the allele conferring the optimal constant recombination rate. Our simulations also confirm the results of theoretical studies showing that condition-dependent recombination cannot evolve in diploids on the basis of direct fitness-dependent effects alone. Therefore, the evolution of condition-dependent recombination in diploids can be driven by indirect effects alone, i.e. by modifier effects on the selected system. This article is part of the themed issue ‘Evolutionary causes and consequences of recombination rate variation in sexual organisms’.

Parasitism, immune response, and egg production of the spearhead bluet (Coenagrion hastulatum) damselfly

2017 ◽  
Vol 95 (5) ◽  
pp. 367-372
Author(s):  
Kari M. Kaunisto ◽  
Pipsa Kaunisto ◽  
Jaakko J. Ilvonen ◽  
Jukka Suhonen
Keyword(s):  
Immune Response ◽  
Egg Production ◽  
Parasite Species ◽  
Wing Length ◽  
Empirical Studies ◽  
Theoretical Models ◽  
Water Mites ◽  
Negative Effect ◽  
Different Populations ◽  
Individual Size

Theoretical models predict that parasites reduce reproductive success of their hosts, but very few empirical studies have given support to this. Using the spearhead bluet (Coenagrion hastulatum (Charpentier, 1825)) damselfly, we tested how immune response, wing length, and the number of both endo- and ecto-parasites affect egg production of host damselflies. The study was conducted with four different populations in southwest Finland. We found a negative association between endoparasitic gregarines and number of host eggs. Furthermore, immune response increased with the number of water mites, but decreased with the number of eggs. Contrary to previous studies with other damselfly species, the number of ectoparasitic water mites did not affect the number of eggs. Moreover, wing length, used as an indicator of individual size, was not associated with egg numbers. The negative effect of gregarine parasites on egg numbers is likely to affect the composition of host populations, i.e., damselflies that show higher resistance to these endoparasites will have more of their offspring represented in subsequent generations. In future, more experimental research on the varying effects of different parasite species on the number of eggs is needed.

scholarly journals Sperm morphology and sperm velocity in passerine birds

2008 ◽  
Vol 276 (1659) ◽  
pp. 1175-1181 ◽  
Author(s):  
Stefan Lüpold ◽  
Sara Calhim ◽  
Simone Immler ◽  
Tim R Birkhead
Keyword(s):  
Sperm Morphology ◽  
Empirical Studies ◽  
Theoretical Models ◽  
Study Groups ◽  
Passerine Birds ◽  
Single Family ◽  
Sperm Velocity ◽  
Evolutionary Forces ◽  
Wide Range ◽  
Main Determinants

Sperm velocity is one of the main determinants of the outcome of sperm competition. Since sperm vary considerably in their morphology between and within species, it seems likely that sperm morphology is associated with sperm velocity. Theory predicts that sperm velocity may be increased by enlarged midpiece (energetic component) or flagellum length (kinetic component), or by particular ratios between sperm components, such as between flagellum length and head size. However, such associations have rarely been found in empirical studies. In a comparative framework in passerine birds, we tested these theoretical predictions both across a wide range of species and within a single family, the New World blackbirds (Icteridae). In both study groups, sperm velocity was influenced by sperm morphology in the predicted direction. Consistent with theoretical models, these results show that selection on sperm morphology and velocity are likely to be concomitant evolutionary forces.

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