scholarly journals Spatially-induced nestedness in a neutral model of phage-bacteria networks

2017 ◽  
Author(s):  
Sergi Valverde ◽  
Santiago F. Elena ◽  
Ricard Solé
Keyword(s):  
Emergent Property ◽  
Continuous Approximation ◽  
Neutral Model ◽  
A Genome ◽  
Spatial Lattice ◽  
Recognition Rule ◽  
Patterns Of Interaction ◽  
Allele Model ◽  
Antagonistic Interactions ◽  
Diverse Virus

Ecological networks, both displaying mutualistic or antagonistic interactions, seem to share common structural traits: the presence of nestedness and modularity. A variety of model approaches and hypothesis have been formulated concerning the significance and implications of these properties. In phage-bacteria bipartite infection networks, nestedness seems to be the rule in many different contexts. Modeling the coevolution of a diverse virus-host ensemble is a difficult task, given the dimensionality and multi parametric nature of a standard continuous approximation. Here we show that this can actually be overcome by using a simple model of coevolving digital genomes on a spatial lattice and having exactly the same properties, i.e. a genome-independent fitness associated to fixed growth and death parameters. A matching allele model of phage-virus recognition rule is enough to generate a complex, diverse ecosystem with heterogeneous patterns of interaction and nestedness, provided that interactions take place under a spatially-constrained setting. It is found that nestedness seems to be an emergent property of the coevolutionary dynamics. Our results indicate that the enhanced diversity resulting from localized interactions strongly promotes the presence of nested infection matrices.

scholarly journals Stable coexistence in plant-pollinator-herbivore communities requires balanced mutualistic vs antagonistic interactions

2021 ◽  
Author(s):  
Youssef Yacine ◽  
Nicolas Loeuille
Keyword(s):  
Emergent Property ◽  
Empirical Literature ◽  
Ecological Communities ◽  
Trade Off ◽  
Stable Coexistence ◽  
Multiple Species ◽  
Plant Pollinator ◽  
Herbivore Communities ◽  
Antagonistic Interactions

Ecological communities consist of multiple species interacting in diverse ways. Understanding the mechanisms supporting coexistence requires accounting for such a diversity. Because most works focus either on mutualism or predation, how pollination and herbivory interactively determine the stable coexistence in plant-pollinator-herbivore communities is still poorly understood. Studying the typical three-species module of such communities, we determine the conditions allowing stable coexistence then investigate how its maintenance constrains the relative interaction strengths. Our results show that coexistence is possible if pollination is sufficiently strong relative to herbivory, while its stability is possible if herbivory is sufficiently strong relative to pollination. A balance between pollination and herbivory is therefore required. Interestingly, shared preferences for plant phenotypes, that would favor such balance, have been frequently reported in the empirical literature. The identified ecological trade-off between attracting pollinators and deterring herbivores therefore also appears as an emergent property of stable plant-pollinator-herbivore communities.

scholarly journals THE SAMPLING DISTRIBUTION OF LINKAGE DISEQUILIBRIUM UNDER AN INFINITE ALLELE MODEL WITHOUT SELECTION

Genetics ◽  
1985 ◽  
Vol 109 (3) ◽  
pp. 611-631
Author(s):  
Richard R Hudson
Keyword(s):  
Linkage Disequilibrium ◽  
Joint Distribution ◽  
High Linkage Disequilibrium ◽  
Allele Frequencies ◽  
Sufficient Information ◽  
Neutral Model ◽  
Infinite Allele Model ◽  
Sampling Distributions ◽  
The Mean ◽  
Allele Model

ABSTRACT The sampling distributions of several statistics that measure the association of alleles on gametes (linkage disequilibrium) are estimated under a two-locus neutral infinite allele model using an efficient Monte Carlo method. An often used approximation for the mean squared linkage disequilibrium is shown to be inaccurate unless the proper statistical conditioning is used. The joint distribution of linkage disequilibrium and the allele frequencies in the sample is studied. This estimated joint distribution is sufficient for obtaining an approximate maximum likelihood estimate of C = 4Nc, where N is the population size and c is the recombination rate. It has been suggested that observations of high linkage disequilibrium might be a good basis for rejecting a neutral model in favor of a model in which natural selection maintains genetic variation. It is found that a single sample of chromosomes, examined at two loci cannot provide sufficient information for such a test if C < 10, because with C this small, very high levels of linkage disequilibrium are not unexpected under the neutral model. In samples of size 50, it is found that, even when C is as large as 50, the distribution of linkage disequilibrium conditional on the allele frequencies is substantially different from the distribution when there is no linkage between the loci. When conditioned on the number of alleles at each locus in the sample, all of the sample statistics examined are nearly independent of λ = 4Nμ, where μ is the neutral mutation rate.

scholarly journals A Multilocus Sequence Survey inArabidopsis thalianaReveals a Genome-Wide Departure From a Neutral Model of DNA Sequence Polymorphism

Genetics ◽  
2005 ◽  
Vol 169 (3) ◽  
pp. 1601-1615 ◽  
Author(s):  
Karl J. Schmid ◽  
Sebastian Ramos-Onsins ◽  
Henriette Ringys-Beckstein ◽  
Bernd Weisshaar ◽  
Thomas Mitchell-Olds
Keyword(s):  
Dna Sequence ◽  
Sequence Polymorphism ◽  
Neutral Model ◽  
Genome Wide ◽  
A Genome ◽  
Dna Sequence Polymorphism

Linguistic Interactions: A Therapeutic Consideration for Adults With Aphasia

2008 ◽  
Vol 17 (3) ◽  
pp. 93-98
Author(s):  
Lynn E. Fox
Keyword(s):  
Clinical Outcomes ◽  
Social Contexts ◽  
Interaction Models ◽  
Social Communities ◽  
Wernicke's Aphasia ◽  
Communication Challenges ◽  
Therapeutic Consideration ◽  
Patterns Of Interaction ◽  
Structural Language

Abstract Linguistic interaction models suggest that interrelationships arise between structural language components and between structural and pragmatic components when language is used in social contexts. The linguist, David Crystal (1986, 1987), has proposed that these relationships are central, not peripheral, to achieving desired clinical outcomes. For individuals with severe communication challenges, erratic or unpredictable relationships between structural and pragmatic components can result in atypical patterns of interaction between them and members of their social communities, which may create a perception of disablement. This paper presents a case study of a woman with fluent, Wernicke's aphasia that illustrates how attention to patterns of linguistic interaction may enhance AAC intervention for adults with aphasia.

Establishment of a genome-wide RNAi screen; Identification of novel genes involved in clonal maintenance of ALL

2014 ◽  
Vol 226 (03) ◽  
Author(s):  
F Ponthan ◽  
D Pal ◽  
J Vormoor ◽  
O Heidenreich
Keyword(s):  
Rnai Screen ◽  
Novel Genes ◽  
Genome Wide ◽  
A Genome
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