scholarly journals The Evolutionary Dynamics of Hyperparasites

2021 ◽  
Author(s):  
Graham R Northrup ◽  
Steven R Parratt ◽  
Carly Rozins ◽  
Anna-Liisa Laine ◽  
Mike Boots
Keyword(s):  
Evolutionary Dynamics ◽  
Modeling Framework ◽  
Bacterial Diseases ◽  
Chestnut Blight Fungus ◽  
Complex Interactions ◽  
Pairwise Interactions ◽  
Evolution Of Virulence ◽  
Wide Range ◽  
Evolutionary Trajectories ◽  
The Impact

AbstractEvolutionary theory has typically focused on pairwise interactions, such as those between hosts and parasites, with relatively little work on more complex interactions including hyperparasites: parasites of parasites. Hyperparasites are common in nature, with the chestnut blight fungus virus CHV-1 a well-known natural example, but also notably include the phages of important human bacterial diseases. Theory on hyperparasitism has mostly focused on their impact on the evolution of virulence of their parasite host and relatively little is known about evolutionary trajectories of hyperparasites themselves. Our general modeling framework highlights the central role the that ability of a hyperparasite to be transmitted with its parasite plays in their evolution. Hyperparasites which transmit with their parasite hosts (hitchhike) will be selected for lower virulence, trending towards hypermutualism or hypercommensalism and select against causing a reduction in parasite virulence (hypovirulence). We examine the impact on the evolution of hyperparasite systems a of a wide range of host and parasite traits showing, for example, that high parasite virulence selects for higher hyperparasite virulence feeding back into selection for hypovirulence in the parasite. Our results have implications for hyperparasite research, both as biocontrol agents and for understanding of how hyperparasites shape community ecology and evolution.

scholarly journals The importance of species interactions in eco-evolutionary community dynamics under climate change

2021 ◽  
Vol 12 (1) ◽  
Author(s):  
Anna Åkesson ◽  
Alva Curtsdotter ◽  
Anna Eklöf ◽  
Bo Ebenman ◽  
Jon Norberg ◽  
...  
Keyword(s):  
Climate Change ◽  
Species Interactions ◽  
Community Dynamics ◽  
Evolutionary Dynamics ◽  
Negative Impact ◽  
Trophic Levels ◽  
Temperature Dependent ◽  
Modeling Framework ◽  
Impact Of Climate Change ◽  
The Impact

AbstractEco-evolutionary dynamics are essential in shaping the biological response of communities to ongoing climate change. Here we develop a spatially explicit eco-evolutionary framework which features more detailed species interactions, integrating evolution and dispersal. We include species interactions within and between trophic levels, and additionally, we incorporate the feature that species’ interspecific competition might change due to increasing temperatures and affect the impact of climate change on ecological communities. Our modeling framework captures previously reported ecological responses to climate change, and also reveals two key results. First, interactions between trophic levels as well as temperature-dependent competition within a trophic level mitigate the negative impact of climate change on biodiversity, emphasizing the importance of understanding biotic interactions in shaping climate change impact. Second, our trait-based perspective reveals a strong positive relationship between the within-community variation in preferred temperatures and the capacity to respond to climate change. Temperature-dependent competition consistently results both in higher trait variation and more responsive communities to altered climatic conditions. Our study demonstrates the importance of species interactions in an eco-evolutionary setting, further expanding our knowledge of the interplay between ecological and evolutionary processes.

scholarly journals Theoretical study of the impact of adaptation on cell-fate heterogeneity and fractional killing

2020 ◽  
Vol 10 (1) ◽  
Author(s):  
Julien Hurbain ◽  
Darka Labavić ◽  
Quentin Thommen ◽  
Benjamin Pfeuty
Keyword(s):  
Cell Fate ◽  
Stochastic Dynamics ◽  
Biochemical Networks ◽  
Stochastic Bifurcation ◽  
Modeling Framework ◽  
Life And Death ◽  
Cell Fate Decisions ◽  
Wide Range ◽  
Adaptation Response ◽  
The Impact

Abstract Fractional killing illustrates the cell propensity to display a heterogeneous fate response over a wide range of stimuli. The interplay between the nonlinear and stochastic dynamics of biochemical networks plays a fundamental role in shaping this probabilistic response and in reconciling requirements for heterogeneity and controllability of cell-fate decisions. The stress-induced fate choice between life and death depends on an early adaptation response which may contribute to fractional killing by amplifying small differences between cells. To test this hypothesis, we consider a stochastic modeling framework suited for comprehensive sensitivity analysis of dose response curve through the computation of a fractionality index. Combining bifurcation analysis and Langevin simulation, we show that adaptation dynamics enhances noise-induced cell-fate heterogeneity by shifting from a saddle-node to a saddle-collision transition scenario. The generality of this result is further assessed by a computational analysis of a detailed regulatory network model of apoptosis initiation and by a theoretical analysis of stochastic bifurcation mechanisms. Overall, the present study identifies a cooperative interplay between stochastic, adaptation and decision intracellular processes that could promote cell-fate heterogeneity in many contexts.

scholarly journals Mutation rate dynamics reflect ecological change in an emerging zoonotic pathogen

PLoS Genetics ◽  
2021 ◽  
Vol 17 (11) ◽  
pp. e1009864
Author(s):  
Gemma G. R. Murray ◽  
Andrew J. Balmer ◽  
Josephine Herbert ◽  
Nazreen F. Hadijirin ◽  
Caroline L. Kemp ◽  
...  
Keyword(s):  
Genome Size ◽  
Mutation Rate ◽  
Evolutionary Dynamics ◽  
Bacterial Species ◽  
Invasive Disease ◽  
Mutation Rates ◽  
Ecological Change ◽  
Zoonotic Pathogen ◽  
Wide Range ◽  
The Impact

Mutation rates vary both within and between bacterial species, and understanding what drives this variation is essential for understanding the evolutionary dynamics of bacterial populations. In this study, we investigate two factors that are predicted to influence the mutation rate: ecology and genome size. We conducted mutation accumulation experiments on eight strains of the emerging zoonotic pathogen Streptococcus suis. Natural variation within this species allows us to compare tonsil carriage and invasive disease isolates, from both more and less pathogenic populations, with a wide range of genome sizes. We find that invasive disease isolates have repeatedly evolved mutation rates that are higher than those of closely related carriage isolates, regardless of variation in genome size. Independent of this variation in overall rate, we also observe a stronger bias towards G/C to A/T mutations in isolates from more pathogenic populations, whose genomes tend to be smaller and more AT-rich. Our results suggest that ecology is a stronger correlate of mutation rate than genome size over these timescales, and that transitions to invasive disease are consistently accompanied by rapid increases in mutation rate. These results shed light on the impact that ecology can have on the adaptive potential of bacterial pathogens.

scholarly journals Human Bartonellosis: An Underappreciated Public Health Problem?

2019 ◽  
Vol 4 (2) ◽  
pp. 69 ◽  
Author(s):  
Mercedes A. Cheslock ◽  
Monica E. Embers
Keyword(s):  
Public Health ◽  
Disease Transmission ◽  
Severe Disease ◽  
Public Health Problem ◽  
Cat Scratch Disease ◽  
Bartonella Species ◽  
Complex Interactions ◽  
Wide Range ◽  
Causative Agents ◽  
The Impact

Bartonella spp. bacteria can be found around the globe and are the causative agents of multiple human diseases. The most well-known infection is called cat-scratch disease, which causes mild lymphadenopathy and fever. As our knowledge of these bacteria grows, new presentations of the disease have been recognized, with serious manifestations. Not only has more severe disease been associated with these bacteria but also Bartonella species have been discovered in a wide range of mammals, and the pathogens’ DNA can be found in multiple vectors. This review will focus on some common mammalian reservoirs as well as the suspected vectors in relation to the disease transmission and prevalence. Understanding the complex interactions between these bacteria, their vectors, and their reservoirs, as well as the breadth of infection by Bartonella around the world will help to assess the impact of Bartonellosis on public health.

scholarly journals Jump around: transposons in and out of the laboratory

F1000Research ◽  
2020 ◽  
Vol 9 ◽  
pp. 135
Author(s):  
Anuj Kumar
Keyword(s):  
Transposable Elements ◽  
Dna Sequences ◽  
Major Constituent ◽  
Mobile Dna ◽  
Mutagenic Potential ◽  
Complex Interactions ◽  
Wide Range ◽  
Transposon Insertions ◽  
The Impact

Since Barbara McClintock’s groundbreaking discovery of mobile DNA sequences some 70 years ago, transposable elements have come to be recognized as important mutagenic agents impacting genome composition, genome evolution, and human health. Transposable elements are a major constituent of prokaryotic and eukaryotic genomes, and the transposition mechanisms enabling transposon proliferation over evolutionary time remain engaging topics for study, suggesting complex interactions with the host, both antagonistic and mutualistic. The impact of transposition is profound, as over 100 human heritable diseases have been attributed to transposon insertions. Transposition can be highly mutagenic, perturbing genome integrity and gene expression in a wide range of organisms. This mutagenic potential has been exploited in the laboratory, where transposons have long been utilized for phenotypic screening and the generation of defined mutant libraries. More recently, barcoding applications and methods for RNA-directed transposition are being used towards new phenotypic screens and studies relevant for gene therapy. Thus, transposable elements are significant in affecting biology both in vivo and in the laboratory, and this review will survey advances in understanding the biological role of transposons and relevant laboratory applications of these powerful molecular tools.

scholarly journals Multiple Mutualist Effects generate synergistic selection and strengthen fitness alignment in a tripartite interaction between legumes, rhizobia, and mycorrhizal fungi

2021 ◽  
Author(s):  
Michelle E. Afkhami ◽  
Maren L. Friesen ◽  
John R. Stinchcombe
Keyword(s):  
Reproductive Success ◽  
Host Plant ◽  
Medicago Truncatula ◽  
Mycorrhizal Fungi ◽  
Evolutionary Dynamics ◽  
Fitness Effects ◽  
Complex Interactions ◽  
Microevolutionary Change ◽  
Evolutionary Trajectories ◽  
First Time

AbstractNearly all organisms interact with multiple mutualists, and complementarity within these complex interactions can result in synergistic fitness effects. However, it remains largely untested how multiple mutualists impact eco-evolutionary dynamics. We tested how multiple microbial mutualists-- N-fixing bacteria and mycorrrhizal fungi-- affected selection and heritability in their shared host plant (Medicago truncatula), as well as fitness alignment between partners. Our results demonstrate for the first time that multispecies mutualisms synergistically affect selection and heritability of host traits and enhance fitness alignment between mutualists. Specifically, we found that multiple mutualists doubled the strength of selection on a plant architectural trait, resulted in 2-3-fold higher heritability of reproductive success, and more than doubled the strength of fitness alignment between N-fixing bacteria and plants. Taken together, these findings show that synergism generated by multiple mutualisms extends to key components of microevolutionary change, and emphasizes the importance of multiple mutualist effects in understanding evolutionary trajectories.

scholarly journals The importance of species interactions in spatially explicit eco-evolutionary community dynamics under climate change

2020 ◽  
Author(s):  
Anna Åkesson ◽  
Alva Curtsdotter ◽  
Anna Eklöf ◽  
Bo Ebenman ◽  
Jon Norberg ◽  
...  
Keyword(s):  
Climate Change ◽  
Species Interactions ◽  
Community Dynamics ◽  
Evolutionary Dynamics ◽  
Negative Relationship ◽  
Trophic Levels ◽  
Spatially Explicit ◽  
Modeling Framework ◽  
Impact Of Climate Change ◽  
The Impact

AbstractEco-evolutionary dynamics are essential in shaping the biological response of communities to ongoing climate change. Here we develop a spatially explicit eco-evolutionary framework which integrates evolution, dispersal, and species interactions within and between trophic levels. This allows us to analyze how these processes interact to shape species- and community-level dynamics under climate change. Additionally, we incorporate the heretofore unexplored feature that species interactions themselves might change due to increasing temperatures and affect the impact of climate change on ecological communities. The new modeling framework captures previously reported ecological responses to climate change, and also reveals two new key results. First, interactions between trophic levels as well as temperature-dependent competition within a trophic level mitigate the negative impact of climate change on global biodiversity, emphasizing the importance of understanding biotic interactions in shaping climate change impact. Second, using a trait-based perspective, we found a strong negative relationship between the within-community variation in preferred temperatures and the capacity to respond to climate change. Communities resulting from different ecological interaction structures form distinct clusters along this relationship, but varying species’ abilities to disperse and adapt to new temperatures leave it unaffected.

scholarly journals 144 A modeling framework to assess the impact of the texas beef cattle water footprint on livestock sustainability

2019 ◽  
Vol 97 (Supplement_3) ◽  
pp. 147-147
Author(s):  
Hector M Menendez ◽  
Benjamin L Turner ◽  
Luis O Tedeschi
Keyword(s):  
Beef Cattle ◽  
Water Use ◽  
Evaluation System ◽  
Crop Production ◽  
Water Footprint ◽  
Phase Region ◽  
Beef Production ◽  
Modeling Framework ◽  
Wide Range ◽  
The Impact

Abstract Anticipated growth in the demand for beef products driven by increased protein consumption, brings into question the efficiency, sustainability, profitability, and social dimensions of water use for U.S. beef production. Current assessment of U.S. beef production provides a wide range (695 to 14,191 L H2O/kg) of water footprint (WF) measurements of green (rainfed), blue (ground or surface), and grey (waste treatment) water use, but lacks defined region-specific estimates. The objective of this ongoing study is to develop a dynamic mathematical model for Texas beef cattle WF (TXWFB) that allows users to estimate a Texas WF, evaluate assumptions and parameters of current WF methodologies, identify water-use inefficiencies, and provide policy recommendations for a sustainable WF. The TXWFB was developed using Vensim DSS™ and evaluated with the Model Evaluation System™. The TXWFB model correctly replicated the previously published Chapagain and Hoekstra (2003; CH2003) water footprint results for beef cattle with a 36-month lifespan in both grazing [11,915 m3/t (0.4 t)] and industrial beef cattle [9636 m3/t (0.545 t)] systems. Then, parameters (diet composition and water footprints) from the CH2003 model were used as inputs into the TXWFB model to develop baseline scenarios for Texas, using ten climate regions (36-month lifespan; baseline grazing µ = 26,389 m3/t and industrial µ = 24,615 m3/t). The baseline results were then compared to grazing and industrial scenarios with regionalized Texas parameters for pasture, forage, and crop production (evapotranspiration, drought), diet/phase/region (cow-calf, stocker, and feedlot; 24 months). The TXWFB predictions for regional grazing (µ = 7,591 m3/t) and industrial (µ = 5,948 m3/t) results were 71 to 75% less than the baseline scenarios (P < 0.05). We concluded that the TXWFB estimates were considerably smaller than those previously published, suggesting that current WF methodologies can be refined to more adequately assess beef cattle WF in the US.

scholarly journals Effective potential reveals evolutionary trajectories in complex fitness landscapes

2019 ◽  
Author(s):  
Matteo Smerlak
Keyword(s):  
Effective Potential ◽  
Evolutionary Dynamics ◽  
Fitness Landscape ◽  
Coarse Graining ◽  
Fitness Landscapes ◽  
Coarse Grained ◽  
Mutational Robustness ◽  
Sequencing Technologies ◽  
Wide Range ◽  
Evolutionary Trajectories

AbstractGrowing efforts to measure fitness landscapes in molecular and microbial systems are premised on a tight relationship between landscape topography and evolutionary trajectories. This relationship, however, is far from being straightforward: depending on their mutation rate, Darwinian populations can climb the closest fitness peak (survival of the fittest), settle in lower regions with higher mutational robustness (survival of the flattest), or fail to adapt altogether (error catastrophes). These bifurcations highlight that evolution does not necessarily drive populations “from lower peak to higher peak”, as Wright imagined. The problem therefore remains: how exactly does a complex landscape topography constrain evolution, and can we predict where it will go next? Here I introduce a generalization of quasispecies theory which identifies metastable evolutionary states as minima of an effective potential. From this representation I derive a coarse-grained, Markov state model of evolution, which in turn forms a basis for evolutionary predictions across a wide range of mutation rates. Because the effective potential is related to the ground state of a quantum Hamiltonian, my approach could stimulate fruitful interactions between evolutionary dynamics and quantum many-body theory.SIGNIFICANCE STATEMENTThe course of evolution is determined by the relationship between heritable types and their adaptive values, the fitness landscape. Thanks to the explosive development of sequencing technologies, fitness landscapes have now been measured in a diversity of systems from molecules to micro-organisms. How can we turn these data into evolutionary predictions? I show that preferred evolutionary trajectories are revealed when the effects of selection and mutations are blended in a single effective evolutionary force. With this reformulation, the dynamics of selection and mutation becomes Markovian, bringing a wealth of classical visualization and analysis tools to bear on evolutionary dynamics. Among these is a coarse-graining of evolutionary dynamics along its metastable states which greatly reduces the complexity of the prediction problem.

scholarly journals Natural selection constrains neutral diversity across a wide range of species.

2014 ◽  
Author(s):  
Russell B. Corbett-Detig ◽  
Daniel L. Hartl ◽  
Timothy B. Sackton
Keyword(s):  
Genetic Diversity ◽  
Natural Selection ◽  
Population Size ◽  
Neutral Theory ◽  
Genetic Maps ◽  
Modeling Framework ◽  
Neutral Genetic Diversity ◽  
Wide Range ◽  
Census Population Size ◽  
The Impact

The neutral theory of molecular evolution predicts that the amount of neutral polymorphisms within a species will increase proportionally with the census population size (Nc). However, this prediction has not been borne out in practice: while the range of Nc spans many orders of magnitude, levels of genetic diversity within species fall in a comparatively narrow range. Although theoretical arguments have invoked the increased efficacy of natural selection in larger populations to explain this discrepancy, few direct empirical tests of this hypothesis have been conducted. In this work, we provide a direct test of this hypothesis using population genomic data from a wide range of taxonomically diverse species. To do this, we relied on the fact that the impact of natural selection on linked neutral diversity depends on the local recombinational environment. In regions of relatively low recombination, selected variants affect more neutral sites through linkage, and the resulting correlation between recombination and polymorphism allows a quantitative assessment of the magnitude of the impact of selection on linked neutral diversity. By comparing whole-genome polymorphism data and genetic maps using a coalescent modeling framework, we estimate the degree to which natural selection reduces linked neutral diversity for 40 species of obligately sexual eukaryotes. We then show that the magnitude of the impact of natural selection is positively correlated with Nc, based on body size and species range as proxies for census population size. These results demonstrate that natural selection removes more variation at linked neutral sites in species with large Nc than those with small Nc, and provides direct empirical evidence that natural selection constrains levels of neutral genetic diversity across many species. This implies that natural selection may provide an explanation for this longstanding paradox of population genetics.

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