scholarly journals Host-parasite dynamics set the ecological theatre for the evolution of state- and context-dependent dispersal in hosts

2020 ◽  
Author(s):  
Jhelam N. Deshpande ◽  
Oliver Kaltz ◽  
Emanuel A. Fronhofer
Keyword(s):  
Large Scale ◽  
Evolutionary Dynamics ◽  
Host Density ◽  
Temporal Correlation ◽  
Parasite Prevalence ◽  
Reaction Norm ◽  
Context Dependency ◽  
Local Context ◽  
Context Dependent ◽  
Host Parasite

AbstractWhile host-parasite interactions are ubiquitous, the large scale consequences of parasite infections are mainly driven by the spatial context. One trait of pivotal importance for the eco-evolutionary dynamics of such metapopulations is the spatial behaviour of hosts, that is, their dispersal. It is well established that dispersal is not a random process, rather dispersal is informed and may depend on internal and external factors. In host-parasite metapopulations, dispersal may be a function of a host’s infection state, but also of the local context, such as host density or parasite prevalence. Using a dynamical host-parasite metapopulation model, we explore whether host dispersal evolves to be state- and context-dependent and what shapes the evolutionarily stable dispersal reaction norms have. We show that state-dependent dispersal readily evolves in the sense that hosts disperse more when infected. This dispersal bias evolves due to kin selection which is consistent with previous studies. Most importantly, we show that prevalence-dependent dispersal evolves, especially when virulence is high and epidemiological dynamics have predictable signatures. The observed evolutionary outcome, a negatively prevalence-dependent dispersal reaction norm for susceptible hosts, seems counter-intuitive at first. However, our results can be readily explained by the emergent epidemiological dynamics, especially their spatial and temporal correlation patterns. Finally, we show that context-dependency in dispersal may rely on both, prevalence, but also host density cues. Our work provides new insights into the evolution of complex dispersal phenotypes in host-parasite metapopulations as well as on associated feedbacks between ecological dynamics and evolutionary change.

scholarly journals Host age modulates within-host parasite competition

2015 ◽  
Vol 11 (5) ◽  
pp. 20150131 ◽  
Author(s):  
Rony Izhar ◽  
Jarkko Routtu ◽  
Frida Ben-Ami
Keyword(s):  
Evolutionary Dynamics ◽  
Parasite Prevalence ◽  
Host Age ◽  
Individual Level ◽  
Pasteuria Ramosa ◽  
Age Dependent ◽  
The Individual ◽  
Host Parasite ◽  
Parasite Exposure ◽  
Age At Exposure

In many host populations, one of the most striking differences among hosts is their age. While parasite prevalence differences in relation to host age are well known, little is known on how host age impacts ecological and evolutionary dynamics of diseases. Using two clones of the water flea Daphnia magna and two clones of its bacterial parasite Pasteuria ramosa , we examined how host age at exposure influences within-host parasite competition and virulence. We found that multiply-exposed hosts were more susceptible to infection and suffered higher mortality than singly-exposed hosts. Hosts oldest at exposure were least often infected and vice versa. Furthermore, we found that in young multiply-exposed hosts competition was weak, allowing coexistence and transmission of both parasite clones, whereas in older multiply-exposed hosts competitive exclusion was observed. Thus, age-dependent parasite exposure and host demography (age structure) could together play an important role in mediating parasite evolution. At the individual level, our results demonstrate a previously unnoticed interaction of the host's immune system with host age, suggesting that the specificity of immune function changes as hosts mature. Therefore, evolutionary models of parasite virulence might benefit from incorporating age-dependent epidemiological parameters.

The prevalence of avian Plasmodium is higher in undisturbed tropical forests of Cameroon

2009 ◽  
Vol 25 (4) ◽  
pp. 439-447 ◽  
Author(s):  
Camille Bonneaud ◽  
Irem Sepil ◽  
Borja Milá ◽  
Wolfgang Buermann ◽  
John Pollinger ◽  
...  
Keyword(s):  
Rain Forest ◽  
Forest Type ◽  
Natural Populations ◽  
Host Density ◽  
Parasite Prevalence ◽  
Haemosporidian Parasites ◽  
Habitat Differences ◽  
Parasite Infections ◽  
Host Parasite ◽  
Avian Plasmodium

Abstract:Habitat fragmentation and deforestation are thought to disrupt host–parasite interactions and increase the risk of epizootic outbreaks in wild vertebrates. A total of 220 individuals from three species of African rain-forest bird (Andropadus latirostris, Andropadus virens, Cyanomitra obscura), captured in two pristine and two agroforests in Cameroon, were screened for the presence of avian haemosporidian parasites (species of Plasmodium and Haemoproteus) to test whether habitat differences were associated with differences in the prevalence of infectious diseases in natural populations. Thirteen mitochondrial lineages, including 11 Plasmodium and two Haemoproteus lineages were identified. Whereas levels of Haemoproteus spp. infections were too low to permit analysis, the prevalence of infections with Plasmodium spp. reached significantly greater levels in undisturbed mature forests. Importantly however, the significant association between forest type and parasite prevalence was independent of host density effects, suggesting that the association did not reflect changes in host species composition and abundance between forest types. Our results illustrate how characterizing land-cover differences, and hence changes, may be a prerequisite to understanding and predicting patterns of parasite infections in natural populations of rain-forest birds.

scholarly journals Diverse environmental perturbations reveal the evolution and context-dependency of genetic effects on gene expression levels

2021 ◽  
Author(s):  
Amanda J Lea ◽  
Julie Peng ◽  
Julien J Ayroles
Keyword(s):  
Gene Expression ◽  
Complex Traits ◽  
Large Scale ◽  
Context Dependency ◽  
Human Populations ◽  
Evolutionary Mechanisms ◽  
Expression Levels ◽  
Gxe Interactions ◽  
Context Dependent ◽  
Gene Expression Levels

There is increasing appreciation that human complex traits are determined by poorly understood interactions between our genomes and daily environments. These "genotype x environment" (GxE) interactions remain difficult to map at the organismal level, but can be uncovered using molecular phenotypes. To do so at large-scale, we profiled transcriptomes across 12 cellular environments using 544 immortalized B cell lines from the 1000 Genomes Project. We mapped the genetic basis of gene expression across environments and revealed a context-dependent genetic architecture: the average heritability of gene expression levels increased in treatment relative to control conditions and, on average, each treatment revealed expression quantitative trait loci (eQTL) at 11% of genes. In total, 22% of all eQTL were context-dependent, and this group was enriched for trait- and disease-associated loci. Further, evolutionary analyses revealed that positive selection has shaped GxE loci involved in responding to immune challenges and hormones, but not man-made chemicals, suggesting there is reduced opportunity for selection to act on responses to molecules recently introduced into human environments. Together, our work highlights the importance of considering an exposure's evolutionary history when studying and interpreting GxE interactions, and provides new insight into the evolutionary mechanisms that maintain GxE loci in human populations.

Interpreting Seventeenth-Century Probate Documents: John Carter, Master Carpenter in St Albans

2011 ◽  
pp. 66-83
Author(s):  
Jane Harris ◽  
Pat Howe
Keyword(s):  
Seventeenth Century ◽  
Large Scale ◽  
Local Context ◽  
Social Standing ◽  
Close Proximity ◽  
Market Town ◽  
Consumer Age

This is a study of a successful seventeenth-century carpenter in St Albans, John Carter, using probate and other documents, assisted by a large-scale computer database of St Albans residents of the period. Sections of the article cover his family, his work and his house and its contents, which have been reconstructed from his probate inventory and from knowledge of the structure of other local houses of the period. Carter's social standing is discussed, both in its local context and in relation to previous probate inventory analyses. This micro-study sheds unusual light upon aspects of the life of a 'middling sort' of person, living in a thriving market town in close proximity to London, at the beginning of the consumer age.

scholarly journals Diversity and host assemblage of avian haemosporidians in different terrestrial ecoregions of Peru

2021 ◽  
Author(s):  
Luz Garcia-Longoria ◽  
Jaime Muriel ◽  
Sergio Magallanes ◽  
Zaira Hellen Villa-Galarce ◽  
Leonila Ricopa ◽  
...  
Keyword(s):  
Amazon Basin ◽  
Evolutionary Dynamics ◽  
Bird Species ◽  
Host Community ◽  
Bird Diversity ◽  
New Host ◽  
Parasite Richness ◽  
Haemosporidian Parasites ◽  
Avian Haemosporidians ◽  
Host Parasite

Abstract Characterizing the diversity and structure of host-parasite communities is crucial to understanding their eco-evolutionary dynamics. Malaria and related haemosporidian parasites are responsible for fitness loss and mortality in bird species worldwide. However, despite exhibiting the greatest ornithological biodiversity, avian haemosporidians from Neotropical regions are quite unexplored. Here, we analyse the genetic diversity of bird haemosporidian parasites (Plasmodium and Haemoproteus) in 1,336 individuals belonging to 206 bird species to explore for differences in diversity of parasite lineages and bird species across five well-differentiated Peruvian ecoregions. We detected 70 different haemosporidian lineages infecting 74 bird species. We showed that 25 out of the 70 haplotypes had not been previously recorded. Moreover, we also identified 81 new host – parasite interactions representing new host records for these haemosporidian parasites. Our outcomes revealed that the effective diversity (as well as the richness, abundance, and Shannon-Weaver index) for both birds and parasite lineages was higher in Amazon basin ecoregions. Furthermore, we also showed that ecoregions with greater diversity of bird species also had high parasite richness, hence suggesting that host community is crucial in explaining parasite richness. Generalist parasites were found in ecoregions with lower bird diversity, implying that the abundance and richness of hosts may shape the exploitation strategy followed by haemosporidian parasites. These outcomes reveal that Neotropical region is a major reservoir of unidentified haemosporidian lineages. Further studies analysing host distribution and specificity of these parasites in the tropics will provide important knowledge about phylogenetic relationships, phylogeography, and patterns of evolution and distribution of haemosporidian parasites.

Algorithmenkompatibles Verwaltungsrecht?

2021 ◽  
Vol 54 (2) ◽  
pp. 251-272
Author(s):  
Margrit Seckelmann
Keyword(s):  
Computer Code ◽  
Administrative Law ◽  
Context Dependency ◽  
New Paradigm ◽  
Starting Point ◽  
Context Dependent ◽  
Legal Meaning ◽  
Automatic Decisions

Die Übersetzung von Recht in (Computer–)‌Code ist derzeit in aller Munde. Lawrence Lessigs berühmtes Diktum, „Code is Law“ wird neuerdings dahingehend reformuliert, dass „Law“ auch „Code“ sei, dass man bei der Rechtsetzung also zugleich seine rechentechnische Umsetzbarkeit mitzudenken habe. Einen Ansatzpunkt für eine derartige „Algorithmisierbarkeit“ von Recht bietet § 35a des Verwaltungsverfahrensgesetzes des Bundes, wonach „automatisierte“ Entscheidungen in bestimmten Fällen zugelassen werden. Ein aktuelles Papier des Fraunhofer FOKUS-Instituts unter dem Titel „Recht Digital“ denkt dieses weiter und suggeriert, man müsse nur die passenden, eindeutigen Ausdrücke finden, dann sei Recht gleichsam „programmierbar“. Aber genau hier stellt sich das Problem: Rechtssprache ist eine Multi-Adressaten-Sprache, also eine Sprache, die sich ebenso sehr an ein Fachpublikum wie an Laien (Bürgerinnen und Bürger) wendet. Sie ist zudem kontextabhängig. Der aktuelle Hype um den Begriff der „Algorithmisierung“ von Gesetzen verbirgt zudem, dass es sich hierbei um ein Grundproblem von Rechtssprache handelt, das in den 1960er bis 1980er Jahren unter den Paradigmata „Rechts-/Verwaltungsautomation“ oder Rechtskybernetik verhandelt wurde. Wie kann man sich also dem Problem der Kontextabhängigkeit von Recht unter dem neuen Paradigma der Algorithmisierung nähern? Im Beitrag über „Algorithmenkompatibles Verwaltungsrecht? Juristische und sprachwissenschaftliche Überlegungen zu einer ‚Standardisierung von Rechtsbegriffen‘“ werden verschiedene Zugänge zur Schaffung einer „algorithmenkonformen“ Rechtssprache vorgestellt. Letztlich aber vermögen es noch so ausgefeilte technische Methoden nicht, das Problem demokratischer Deliberation zu verdrängen – über die fundamentalen Fragen einer Algorithmisierung der Rechtssprache muss der unmittelbar demokratisch legitimierte Gesetzgeber entscheiden. „Kontext“ und „Text“ geraten insoweit in ein wechselseitiges Abhängigkeitsverhältnis. The translation of law into (computer) code seems to be currently on everyone’s lips. Lawrence Lessigs’ famous dictum “Code is Law” has recently been rephrased saying that “Law” was also “Code”. This means that the wording of laws should directly take their “computer implementability” into consideration. A starting point for those postulations can be seen in the (relatively) new section 35a of the (Federal) Administrative Prodecure Act (Verwaltungsverfahrensgesetz), which allows “automatic” decisions in specific cases. A new paper of the Fraunhofer FOKUS institute takes this up and suggests that we have only to look for the appropriate, unambiguous term that corresponds with an unequivocal legal meaning. In doing so, law could be programmable. But this is exactly the point where the problem arises: laws have more than one addressee; they address lawyers as well as citizens (mostly laypeople). Furthermore, legal terminology is context dependent. The current hype regarding the “algorithmization” of legal terminology also hides the fact that this issue was – more or less – discussed once before under the paradigm “legal cybernetics” between 1960 and 1985. So how can we approach the problem of context-dependency of law under the new paradigm of algorithmization? In our contribution on “Algorithm-compatible administrative law? Legal and linguistic considerations concerning the ‘standardization’ of legal terminology”, we will introduce different approaches to safeguard the compatibility of law with computer technics. But how sophisticated a technical method can be: It is the democratically legitimised parliament that must make the fundamental decisions when it comes to an “algorithmization” of legal terminology, because there is no text without context.

Context-Dependent Modulation of Early Visual Cortical Responses to Numerical and Nonnumerical Magnitudes

2021 ◽  
pp. 1-12
Author(s):  
Joonkoo Park ◽  
Sonia Godbole ◽  
Marty G. Woldorff ◽  
Elizabeth M. Brannon
Keyword(s):  
Visual Processing ◽  
Context Dependency ◽  
Numerical Magnitude ◽  
Continuous Variables ◽  
Processing Stream ◽  
Cortical Responses ◽  
Early Visual Cortex ◽  
Context Dependent ◽  
Visual Cortical ◽  
The Brain

Abstract Whether and how the brain encodes discrete numerical magnitude differently from continuous nonnumerical magnitude is hotly debated. In a previous set of studies, we orthogonally varied numerical (numerosity) and nonnumerical (size and spacing) dimensions of dot arrays and demonstrated a strong modulation of early visual evoked potentials (VEPs) by numerosity and not by nonnumerical dimensions. Although very little is known about the brain's response to systematic changes in continuous dimensions of a dot array, some authors intuit that the visual processing stream must be more sensitive to continuous magnitude information than to numerosity. To address this possibility, we measured VEPs of participants viewing dot arrays that changed exclusively in one nonnumerical magnitude dimension at a time (size or spacing) while holding numerosity constant and compared this to a condition where numerosity was changed while holding size and spacing constant. We found reliable but small neural sensitivity to exclusive changes in size and spacing; however, changing numerosity elicited a much more robust modulation of the VEPs. Together with previous work, these findings suggest that sensitivity to magnitude dimensions in early visual cortex is context dependent: The brain is moderately sensitive to changes in size and spacing when numerosity is held constant, but sensitivity to these continuous variables diminishes to a negligible level when numerosity is allowed to vary at the same time. Neurophysiological explanations for the encoding and context dependency of numerical and nonnumerical magnitudes are proposed within the framework of neuronal normalization.

scholarly journals Evolution of a predator-induced, nonlinear reaction norm

2017 ◽  
Vol 284 (1861) ◽  
pp. 20170859 ◽  
Author(s):  
Mauricio J. Carter ◽  
Martin I. Lind ◽  
Stuart R. Dennis ◽  
William Hentley ◽  
Andrew P. Beckerman
Keyword(s):  
Evolutionary Dynamics ◽  
Daphnia Pulex ◽  
Reaction Norm ◽  
Maximum Response ◽  
Selective Predation ◽  
Evolutionary Trajectory ◽  
Defensive Reaction ◽  
Selection Gradients ◽  
Hunting Strategies ◽  
Evolutionary Response

Inducible, anti-predator traits are a classic example of phenotypic plasticity. Their evolutionary dynamics depend on their genetic basis, the historical pattern of predation risk that populations have experienced and current selection gradients. When populations experience predators with contrasting hunting strategies and size preferences, theory suggests contrasting micro-evolutionary responses to selection. Daphnia pulex is an ideal species to explore the micro-evolutionary response of anti-predator traits because they face heterogeneous predation regimes, sometimes experiencing only invertebrate midge predators and other times experiencing vertebrate fish and invertebrate midge predators. We explored plausible patterns of adaptive evolution of a predator-induced morphological reaction norm. We combined estimates of selection gradients that characterize the various habitats that D. pulex experiences with detail on the quantitative genetic architecture of inducible morphological defences. Our data reveal a fine scale description of daphnid defensive reaction norms, and a strong covariance between the sensitivity to cues and the maximum response to cues. By analysing the response of the reaction norm to plausible, predator-specific selection gradients, we show how in the context of this covariance, micro-evolution may be more uniform than predicted from size-selective predation theory. Our results show how covariance between the sensitivity to cues and the maximum response to cues for morphological defence can shape the evolutionary trajectory of predator-induced defences in D. pulex .

scholarly journals Energy Production Benefits by Wind and Wave Energies for the Autonomous System of Crete

Energies ◽  
2018 ◽  
Vol 11 (10) ◽  
pp. 2741 ◽  
Author(s):  
George Lavidas ◽  
Vengatesan Venugopal
Keyword(s):  
Wind Turbine ◽  
Wave Energy ◽  
Energy Production ◽  
Large Scale ◽  
Capital Expenditure ◽  
Temporal Correlation ◽  
Clean Energy ◽  
Limiting Factor ◽  
Spatio Temporal ◽  
Visual Impacts

At autonomous electricity grids Renewable Energy (RE) contributes significantly to energy production. Offshore resources benefit from higher energy density, smaller visual impacts, and higher availability levels. Offshore locations at the West of Crete obtain wind availability ≈80%, combining this with the installation potential for large scale modern wind turbines (rated power) then expected annual benefits are immense. Temporal variability of production is a limiting factor for wider adaptation of large offshore farms. To this end multi-generation with wave energy can alleviate issues of non-generation for wind. Spatio-temporal correlation of wind and wave energy production exhibit that wind and wave hybrid stations can contribute significant amounts of clean energy, while at the same time reducing spatial constrains and public acceptance issues. Offshore technologies can be combined as co-located or not, altering contribution profiles of wave energy to non-operating wind turbine production. In this study a co-located option contributes up to 626 h per annum, while a non co-located solution is found to complement over 4000 h of a non-operative wind turbine. Findings indicate the opportunities associated not only in terms of capital expenditure reduction, but also in the ever important issue of renewable variability and grid stability.

scholarly journals Neural mechanisms of context-dependent segmentation tested on large-scale recording data

2021 ◽  
Author(s):  
Toshitake Asabuki ◽  
Tomoki Fukai
Keyword(s):  
Cortical Neurons ◽  
Large Scale ◽  
Neural Mechanism ◽  
Imaging Data ◽  
Unsupervised Segmentation ◽  
Spike Sequences ◽  
Multiple Cell ◽  
Context Dependent ◽  
Current Flows ◽  
The Given

The brain performs various cognitive functions by learning the spatiotemporal salient features of the environment. This learning likely requires unsupervised segmentation of hierarchically organized spike sequences, but the underlying neural mechanism is only poorly understood. Here, we show that a recurrent gated network of neurons with dendrites can context-dependently solve difficult segmentation tasks. Dendrites in this model learn to predict somatic responses in a self-supervising manner while recurrent connections learn a context-dependent gating of dendro-somatic current flows to minimize a prediction error. These connections select particular information suitable for the given context from input features redundantly learned by the dendrites. The model selectively learned salient segments in complex synthetic sequences. Furthermore, the model was also effective for detecting multiple cell assemblies repeating in large-scale calcium imaging data of more than 6,500 cortical neurons. Our results suggest that recurrent gating and dendrites are crucial for cortical learning of context-dependent segmentation tasks.

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