scholarly journals Phenotypic plasticity promotes recombination and gene clustering in periodic environments

2016 ◽  
Keyword(s):  
Phenotypic Plasticity ◽  
Genetic Recombination ◽  
Gene Clustering ◽  
Analytic Approximation ◽  
Red Queen Hypothesis ◽  
Modifier Locus ◽  
Changing Environments ◽  
Target Locus ◽  
Host Parasite ◽  
The Impact

AbstractThe impact of changing environments on the evolution of genetic recombination is still unclear. While the Red Queen hypothesis provides a reasonable explanation for recombination, it requires coevolution with antagonistic species, such as host-parasite systems. We present a novel scenario for the evolution of recombination in changing environments: the genomic storage effect due to phenotypic plasticity. Using an analytic approximation and Monte Carlo simulations, we demonstrate that recombination evolves between a target locus that determines fitness, and a modifier locus that modulates the effects of alleles at the target. Evolution of recombination by this plasticity effect does not require antagonistic inter-specific interactions and, unlike in previous models, it occurs when only one target locus codes for a trait under selection. Furthermore, if the effects of multiple target loci are modified by the same plasticity locus, then the recombination rate among the target loci will tend to decrease, clustering the loci that influence a trait. These results provide a novel scenario for the evolution of recombination, highlighting the importance of phenotypic plasticity for recombination modification.

scholarly journals Phenotypic plasticity promotes recombination and gene clustering in periodic environments

2017 ◽  
Author(s):  
Davorka Gulisija ◽  
Joshua B. Plotkin
Keyword(s):  
Phenotypic Plasticity ◽  
Natural Populations ◽  
Gene Clustering ◽  
Analytic Approximation ◽  
Red Queen Hypothesis ◽  
Modifier Locus ◽  
Balanced Polymorphism ◽  
Target Locus ◽  
Single Target ◽  
Host Parasite

While theory offers clear predictions for when recombination will evolve in changing environments, it is unclear what natural scenarios can generate the necessary conditions. The Red Queen hypothesis provides one such scenario in natural populations, but it requires interaction with antagonistic species such as host-parasite systems. We present a novel scenario for the evolution of recombination in finite populations: the genomic storage effect due to phenotypic plasticity. Using an analytic approximation and Monte Carlo simulations we demonstrate that balanced polymorphism and recombination evolve between a target locus that codes for a seasonally selected trait and a plasticity modifier locus that modulates the effects of target-locus alleles. Unlike in prior models, evolution of recombination by this plasticity effect does not require antagonistic inter-specific interactions or a steady influx of mutation, and it occurs even when a single target locus expresses a trait under selection. Furthermore, we show that selection will suppress the recombination rate among multiple polymorphic target loci, even in the absence of epistasis among them, which produces a cluster of linked loci under selection. These results provide a novel biological scenario for the evolution of recombination and supergenes.

scholarly journals Phenotypic plasticity promotes recombination and gene clustering in periodic environments

2017 ◽  
Author(s):  
Davorka Gulisija ◽  
Joshua B. Plotkin
Keyword(s):  
Phenotypic Plasticity ◽  
Natural Populations ◽  
Gene Clustering ◽  
Analytic Approximation ◽  
Red Queen Hypothesis ◽  
Modifier Locus ◽  
Balanced Polymorphism ◽  
Target Locus ◽  
Single Target ◽  
Host Parasite

While theory offers clear predictions for when recombination will evolve in changing environments, it is unclear what natural scenarios can generate the necessary conditions. The Red Queen hypothesis provides one such scenario in natural populations, but it requires interaction with antagonistic species such as host-parasite systems. We present a novel scenario for the evolution of recombination in finite populations: the genomic storage effect due to phenotypic plasticity. Using an analytic approximation and Monte Carlo simulations we demonstrate that balanced polymorphism and recombination evolve between a target locus that codes for a seasonally selected trait and a plasticity modifier locus that modulates the effects of target-locus alleles. Unlike in prior models, evolution of recombination by this plasticity effect does not require antagonistic inter-specific interactions or a steady influx of mutation, and it occurs even when a single target locus expresses a trait under selection. Furthermore, we show that selection will suppress the recombination rate among multiple polymorphic target loci, even in the absence of epistasis among them, which produces a cluster of linked loci under selection. These results provide a novel biological scenario for the evolution of recombination and supergenes.

Neurobiology of phenotypic plasticity in the light of climate change

Neuroforum ◽  
2021 ◽  
Vol 0 (0) ◽  
Author(s):  
Linda C. Weiss
Keyword(s):  
Climate Change ◽  
Phenotypic Plasticity ◽  
Sensory Systems ◽  
Chemical Information ◽  
Adaptive Potential ◽  
Worst Case ◽  
Changing Environments ◽  
Neuronal Signalling ◽  
Physiological Adaptations ◽  
Signalling Cascade

Abstract Phenotypic plasticity describes the ability of an organism with a given genotype to respond to changing environmental conditions through the adaptation of the phenotype. Phenotypic plasticity is a widespread means of adaptation, allowing organisms to optimize fitness levels in changing environments. A core prerequisite for adaptive predictive plasticity is the existence of reliable cues, i.e. accurate environmental information about future selection on the expressed plastic phenotype. Furthermore, organisms need the capacity to detect and interpret such cues, relying on specific sensory signalling and neuronal cascades. Subsequent neurohormonal changes lead to the transformation of phenotype A into phenotype B. Each of these activities is critical for survival. Consequently, anything that could impair an animal’s ability to perceive important chemical information could have significant ecological ramifications. Climate change and other human stressors can act on individual or all of the components of this signalling cascade. In consequence, organisms could lose their adaptive potential, or in the worst case, even become maladapted. Therefore, it is key to understand the sensory systems, the neurobiology and the physiological adaptations that mediate organisms’ interactions with their environment. It is, thus, pivotal to predict the ecosystem-wide effects of global human forcing. This review summarizes current insights on how climate change affects phenotypic plasticity, focussing on how associated stressors change the signalling agents, the sensory systems, receptor responses and neuronal signalling cascades, thereby, impairing phenotypic adaptations.

scholarly journals Phenotypic plasticity promotes balanced polymorphism in periodic environments by a genomic storage effect

2016 ◽  
Author(s):  
Davorka Gulisija ◽  
Yuseob Kim ◽  
Joshua B. Plotkin
Keyword(s):  
Phenotypic Plasticity ◽  
Large Range ◽  
Genetic Model ◽  
Effect Sizes ◽  
Storage Effect ◽  
Recombination Rates ◽  
Modifier Locus ◽  
Balanced Polymorphism ◽  
Analytical Approximations ◽  
Varying Environments

Phenotypic plasticity is known to evolve in perturbed habitats, where it alleviates the deleterious effects of selection. But the effects of plasticity on levels of genetic polymorphism, an important precursor to adaptation in temporally varying environments, are unclear. Here we develop a haploid, two-locus population-genetic model to describe the interplay between a plasticity modifier locus and a target locus subject to periodically varying selection. We find that the interplay between these two loci can produce a 'genomic storage effect' that promotes balanced polymorphism over a large range of parameters, in the absence of all other conditions known to maintain genetic variation. The genomic storage effect arises as recombination allows alleles at the two loci to escape more harmful genetic backgrounds and associate in haplotypes that persist until environmental conditions change. Using both Monte Carlo simulations and analytical approximations we quantify the strength of the genomic storage effect across a range of selection pressures, recombination rates, plasticity modifier effect sizes, and environmental periods.

Non-linear phenomena in host—parasite interactions

Parasitology ◽  
1989 ◽  
Vol 99 (S1) ◽  
pp. S59-S79 ◽  
Author(s):  
R. M. Anderson ◽  
R. M. May ◽  
S. Gupta
Keyword(s):  
Control Measure ◽  
Chemotherapeutic Agents ◽  
Control Measures ◽  
Developmental Cycle ◽  
Helminth Parasites ◽  
Control Effort ◽  
Host Parasite Interactions ◽  
Non Linear ◽  
Host Parasite ◽  
The Impact

SUMMARYThe paper examines non-linear dynamical phenomena in host—parasite interactions by reference to a series of different problems ranging from the impact on transmission of control measures based on vaccination and chemotherapy, to the effects of immunological responses targeted at different stages in a parasite's life-cycle. Throughout, simple mathematical models are employed to aid in interpretation. Analyses reveal that the influence of a defined control measure on the prevalence or intensity of infection, whether vaccination or drug treatment, is non-linearly related to the magnitude of control effort (as defined by the proportion of individuals vaccinated or treated with a drug). Consideration of the relative merits of gametocyte and sporozoite vaccines against malarial parasites suggests that very high levels of cohort immunization will be required to block transmission in endemic areas, with the former type of vaccine being more effective in reducing transmission for a defined level of coverage and the latter being better with respect to a reduction in morbidity. The inclusion of genetic elements in analyses of the transmission of helminth parasites reveals complex non-linear patterns of change in the abundance of different parasite genotypes under selection pressures imposed by either the host immunological defences or the application of chemotherapeutic agents. When resistance genes are present in parasite populations, the degree to which abundance can be suppressed by chemotherapy depends critically on the frequency and intensity of application, with intermediate values of the former being optimal. A more detailed consideration of the impact of immunological defences on parasite population growth within an individual host, by reference to the erythrocytic cycle of malaria, suggests that the effectiveness of a given immunological response is inversely related to the life-expectancy of the target stage in the parasite's developmental cycle.

The changing role of children’s charities delivering early intervention services

2020 ◽  
pp. 145-176
Author(s):  
Alison Body
Keyword(s):  
Early Intervention ◽  
The State ◽  
Policy Changes ◽  
Early Intervention Services ◽  
Changing Environments ◽  
Definition Of ◽  
The Impact ◽  
Changing Role ◽  
Preventative Services

In chapter 6 we explore the impact of commissioning and policy changes on early intervention and preventative services for children delivered by the charitable sector. The definition of early intervention and preventative services is highly contested and politicised within policy and commissioning processes. This reflects an ongoing debate regarding the shifting paradigm of prevention. As the commissioning narrative has developed, there has been an overall disengagement between the voluntary sector providers and State. As the charitable sector is increasingly exposed to intensifying marketization, polarisation of relationships increases. We identify here three ‘types’ of organisational responses to this ever-changing environments; conformers – those charities who align themselves close to the State and regularly reinterpret their mission to fit State logic; the outliers – those charities which reject State approaches to early intervention and seek to deliver services completely independently of the State; and the intermediaries – those charities which walk between conformity and dissent, working with the State when necessary or too their advantage, and walking away when not. We discuss how these types fundamentally alter children’s charities perspectives and experiences of commissioning and the impact this has on their wider work.

scholarly journals Human microRNAs in host–parasite interaction: a review

3 Biotech ◽  
2020 ◽  
Vol 10 (12) ◽  
Author(s):  
Sujay Paul ◽  
Luis M. Ruiz-Manriquez ◽  
Francisco I. Serrano-Cano ◽  
Carolina Estrada-Meza ◽  
Karla A. Solorio-Diaz ◽  
...  
Keyword(s):  
Noncoding Rna ◽  
Fine Tuning ◽  
Transcriptional Level ◽  
Response Modulation ◽  
Rna Molecules ◽  
Small Noncoding Rna ◽  
Diagnosis And Prognosis ◽  
Cell Proliferation And Differentiation ◽  
Host Parasite ◽  
The Impact

AbstractMicroRNAs (miRNAs) are a group of small noncoding RNA molecules with significant capacity to regulate the gene expression at the post-transcriptional level in a sequence-specific manner either through translation repression or mRNA degradation triggering a fine-tuning biological impact. They have been implicated in several processes, including cell growth and development, signal transduction, cell proliferation and differentiation, metabolism, apoptosis, inflammation, and immune response modulation. However, over the last few years, extensive studies have shown the relevance of miRNAs in human pathophysiology. Common human parasitic diseases, such as Malaria, Leishmaniasis, Amoebiasis, Chagas disease, Schistosomiasis, Toxoplasmosis, Cryptosporidiosis, Clonorchiasis, and Echinococcosis are the leading cause of death worldwide. Thus, identifying and characterizing parasite-specific miRNAs and their host targets, as well as host-related miRNAs, are important for a deeper understanding of the pathophysiology of parasite-specific diseases at the molecular level. In this review, we have demonstrated the impact of human microRNAs during host−parasite interaction as well as their potential to be used for diagnosis and prognosis purposes.

scholarly journals Deciphering the Impact of a Bacterial Infection on Meiotic Recombination in Arabidopsis with Fluorescence Tagged Lines

Genes ◽  
2020 ◽  
Vol 11 (7) ◽  
pp. 832
Author(s):  
Ariane Gratias ◽  
Valérie Geffroy
Keyword(s):  
Pseudomonas Syringae ◽  
Meiotic Recombination ◽  
Recombination Rate ◽  
Evolutionary Dynamics ◽  
Genetic Recombination ◽  
Dna Recombination ◽  
Resistance Mechanism ◽  
Sequence Exchange ◽  
Significant Difference ◽  
The Impact

Plants are under strong evolutionary pressure to maintain surveillance against pathogens. One major disease resistance mechanism is based on NB-LRR (NLR) proteins that specifically recognize pathogen effectors. The cluster organization of the NLR gene family could favor sequence exchange between NLR genes via recombination, favoring their evolutionary dynamics. Increasing data, based on progeny analysis, suggest the existence of a link between the perception of biotic stress and the production of genetic diversity in the offspring. This could be driven by an increased rate of meiotic recombination in infected plants, but this has never been strictly demonstrated. In order to test if pathogen infection can increase DNA recombination in pollen meiotic cells, we infected Arabidopsis Fluorescent Tagged Lines (FTL) with the virulent bacteria Pseudomonas syringae. We measured the meiotic recombination rate in two regions of chromosome 5, containing or not an NLR gene cluster. In all tested intervals, no significant difference in genetic recombination frequency between infected and control plants was observed. Although it has been reported that pathogen exposure can sometimes increase the frequency of recombinant progeny in plants, our findings suggest that meiotic recombination rate in Arabidopsis may be resilient to at least some pathogen attack. Alternative mechanisms are discussed.

scholarly journals Phenotypic plasticity of stomatal and photosynthetic features of four Picea species in two contrasting common gardens

AoB Plants ◽  
2019 ◽  
Vol 11 (4) ◽  
Author(s):  
Ming Hao Wang ◽  
Jing Ru Wang ◽  
Xiao Wei Zhang ◽  
Ai Ping Zhang ◽  
Shan Sun ◽  
...  
Keyword(s):  
Climate Change ◽  
Phenotypic Plasticity ◽  
Global Climate ◽  
Physiological Activity ◽  
Climatic Conditions ◽  
Leaf Mass Per Area ◽  
Picea Crassifolia ◽  
Common Gardens ◽  
Picea Species ◽  
The Impact

Abstract Global climate change is expected to affect mountain ecosystems significantly. Phenotypic plasticity, the ability of any genotype to produce a variety of phenotypes under different environmental conditions, is critical in determining the ability of species to acclimate to current climatic changes. Here, to simulate the impact of climate change, we compared the physiology of species of the genus Picea from different provenances and climatic conditions and quantified their phenotypic plasticity index (PPI) in two contrasting common gardens (dry vs. wet), and then considered phenotypic plastic effects on their future adaptation. The mean PPI of the photosynthetic features studied was higher than that of the stomatal features. Species grown in the arid and humid common gardens were differentiated: the stomatal length (SL) and width (SW) on the adaxial surface, the transpiration rate (Tr) and leaf mass per area (LMA) were more highly correlated with rainfall than other traits. There were no significant relationships between the observed plasticity and the species’ original habitat, except in P. crassifolia (from an arid habitat) and P. asperata (from a humid habitat). Picea crassifolia exhibited enhanced instantaneous efficiency of water use (PPI = 0.52) and the ratio of photosynthesis to respiration (PPI = 0.10) remained constant; this species was, therefore, considered to the one best able to acclimate when faced with the effects of climate change. The other three species exhibited reduced physiological activity when exposed to water limitation. These findings indicate how climate change affects the potential roles of plasticity in determining plant physiology, and provide a basis for future reforestation efforts in China.

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