scholarly journals Occupancy patterns in superorganisms: a spin-glass approach to ant exploration

2020 ◽  
Vol 7 (12) ◽  
pp. 201250
Author(s):  
Javier Cristín ◽  
Frederic Bartumeus ◽  
Vicenç Méndez ◽  
Daniel Campos
Keyword(s):  
Spin Glass ◽  
Statistical Physics ◽  
Spatial Organization ◽  
Null Model ◽  
Social Strategies ◽  
Individual Level ◽  
Aphaenogaster Senilis ◽  
Occupancy Patterns ◽  
Biological Interpretation ◽  
The Individual

Emergence of collective, as well as superorganism-like, behaviour in biological populations requires the existence of rules of communication, either direct or indirect, between organisms. Because reaching an understanding of such rules at the individual level can be often difficult, approaches carried out at higher, or effective, levels of description can represent a useful alternative. In the present work, we show how a spin-glass approach characteristic of statistical physics can be used as a tool to characterize the properties of the spatial occupancy patterns of a biological population. We exploit the presence of pairwise interactions in spin-glass models for detecting correlations between occupancies at different sites in the media. Such correlations, we claim, represent a proxy to the existence of planned and/or social strategies in the spatial organization of the population. Our spin-glass approach does not only identify those correlations but produces a statistical replica of the system (at the level of occupancy patterns) that can be subsequently used for testing alternative conditions/hypothesis. Here, this methodology is presented and illustrated for a particular case of study: we analyse occupancy patterns of Aphaenogaster senilis ants during foraging through a simplified environment consisting of a discrete (tree-like) artificial lattice. Our spin-glass approach consistently reproduces the experimental occupancy patterns across time, and besides, an intuitive biological interpretation of the parameters is attainable. Likewise, we prove that pairwise correlations are important for reproducing these dynamics by showing how a null model, where such correlations are neglected, would perform much worse; this provides a solid evidence to the existence of superorganism-like strategies in the colony.

scholarly journals A small number of workers with specific personality traits perform tool use in ants

eLife ◽  
2020 ◽  
Vol 9 ◽  
Author(s):  
István Maák ◽  
Garyk Roelandt ◽  
Patrizia d'Ettorre
Keyword(s):  
Personality Traits ◽  
Tool Use ◽  
Division Of Labour ◽  
Exploratory Activity ◽  
Liquid Food ◽  
Personality Tests ◽  
Individual Level ◽  
Aphaenogaster Senilis ◽  
Individual Personality ◽  
The Individual

Ants use debris as tools to collect and transport liquid food to the nest. Previous studies showed that this behaviour is flexible whereby ants learn to use artificial material that is novel to them and select tools with optimal soaking properties. However, the process of tool use has not been studied at the individual level. We investigated whether workers specialise in tool use and whether there is a link between individual personality traits and tool use in the ant Aphaenogaster senilis. Only a small number of workers performed tool use and they did it repeatedly, although they also collected solid food. Personality predicted the probability to perform tool use: ants that showed higher exploratory activity and were more attracted to a prey in the personality tests became the new tool users when previous tool users were removed from the group. This suggests that, instead of extreme task specialisation, variation in personality traits within the colony may improve division of labour.

scholarly journals On the effect of asymmetrical trait inheritance on models of trait evolution

2019 ◽  
Author(s):  
Pablo Duchen ◽  
Michael L. Alfaro ◽  
Jonathan Rolland ◽  
Nicolas Salamin ◽  
Daniele Silvestro
Keyword(s):  
Quantitative Trait ◽  
Comparative Methods ◽  
Simulation Framework ◽  
Trait Evolution ◽  
Individual Level ◽  
Parameter Estimations ◽  
Wide Range ◽  
Biological Interpretation ◽  
Individual Based Simulation ◽  
The Individual

AbstractCurrent phylogenetic comparative methods modeling quantitative trait evolution generally assume that, during speciation, phenotypes are inherited identically between the two daughter species. This, however, neglects the fact that species consist of a set of individuals, each bearing its own trait value. Indeed, because descendent populations after speciation are samples of a parent population, we can expect their mean phenotypes to randomly differ from one another potentially generating a “jump” of mean phenotypes due to asymmetrical trait inheritance at cladogenesis. Here, we aim to clarify the effect of asymmetrical trait inheritance at speciation on macroevolutionary analyses, focusing on model testing and parameter estimation using some of the most common models of quantitative trait evolution. We developed an individual-based simulation framework in which the evolution of species phenotypes is determined by trait changes at the individual level accumulating across generations and cladogenesis occurs then by separation of subsets of the individuals into new lineages. Through simulations, we assess the magnitude of phenotypic jumps at cladogenesis under different modes of trait inheritance at speciation. We show that even small jumps can strongly alter both the results of model selection and parameter estimations, potentially affecting the biological interpretation of the estimated mode of evolution of a trait. Our results call for caution when interpreting analyses of trait evolution, while highlighting the importance of testing a wide range of alternative models. In the light of our findings, we propose that future methodological advances in comparative methods should more explicitly model the intra-specific variability around species mean phenotypes and how it is inherited at speciation.

scholarly journals Cortical astrocytes develop in a plastic manner at both clonal and cellular levels

2019 ◽  
Vol 10 (1) ◽  
Author(s):  
Solène Clavreul ◽  
Lamiae Abdeladim ◽  
Edwin Hernández-Garzón ◽  
Dragos Niculescu ◽  
Jason Durand ◽  
...  
Keyword(s):  
Spatial Organization ◽  
Local Environment ◽  
Lineage Tracing ◽  
Individual Level ◽  
Complex Morphology ◽  
Cortical Astrocyte ◽  
Mouse Cortex ◽  
Imaging Approach ◽  
Before And After ◽  
The Individual

Abstract Astrocytes play essential roles in the neural tissue where they form a continuous network, while displaying important local heterogeneity. Here, we performed multiclonal lineage tracing using combinatorial genetic markers together with a new large volume color imaging approach to study astrocyte development in the mouse cortex. We show that cortical astrocyte clones intermix with their neighbors and display extensive variability in terms of spatial organization, number and subtypes of cells generated. Clones develop through 3D spatial dispersion, while at the individual level astrocytes acquire progressively their complex morphology. Furthermore, we find that the astroglial network is supplied both before and after birth by ventricular progenitors that scatter in the neocortex and can give rise to protoplasmic as well as pial astrocyte subtypes. Altogether, these data suggest a model in which astrocyte precursors colonize the neocortex perinatally in a non-ordered manner, with local environment likely determining astrocyte clonal expansion and final morphotype.

scholarly journals On the Effect of Asymmetrical Trait Inheritance on Models of Trait Evolution

2020 ◽  
Author(s):  
Pablo Duchen ◽  
Michael L Alfaro ◽  
Jonathan Rolland ◽  
Nicolas Salamin ◽  
Daniele Silvestro
Keyword(s):  
Quantitative Trait ◽  
Intraspecific Variability ◽  
Comparative Methods ◽  
Trait Evolution ◽  
Individual Level ◽  
Parameter Estimations ◽  
Wide Range ◽  
Biological Interpretation ◽  
Individual Based Simulation ◽  
The Individual

Abstract Current phylogenetic comparative methods modeling quantitative trait evolution generally assume that, during speciation, phenotypes are inherited identically between the two daughter species. This, however, neglects the fact that species consist of a set of individuals, each bearing its own trait value. Indeed, because descendent populations after speciation are samples of a parent population, we can expect their mean phenotypes to randomly differ from one another potentially generating a “jump” of mean phenotypes due to asymmetrical trait inheritance at cladogenesis. Here, we aim to clarify the effect of asymmetrical trait inheritance at speciation on macroevolutionary analyses, focusing on model testing and parameter estimation using some of the most common models of quantitative trait evolution. We developed an individual-based simulation framework in which the evolution of phenotypes is determined by trait changes at the individual level accumulating across generations, and cladogenesis occurs then by separation of subsets of the individuals into new lineages. Through simulations, we assess the magnitude of phenotypic jumps at cladogenesis under different modes of trait inheritance at speciation. We show that even small jumps can strongly alter both the results of model selection and parameter estimations, potentially affecting the biological interpretation of the estimated mode of evolution of a trait. Our results call for caution when interpreting analyses of trait evolution, while highlighting the importance of testing a wide range of alternative models. In the light of our findings, we propose that future methodological advances in comparative methods should more explicitly model the intraspecific variability around species mean phenotypes and how it is inherited at speciation.

scholarly journals The polarization within and across individuals: the hierarchical Ising opinion model

2020 ◽  
Vol 8 (2) ◽  
Author(s):  
Han L J van der Maas ◽  
Jonas Dalege ◽  
Lourens Waldorp
Keyword(s):  
Group Dynamics ◽  
Statistical Physics ◽  
Social Dynamics ◽  
Opinion Dynamics ◽  
Individual Level ◽  
Bounded Confidence ◽  
The Social ◽  
Resistance To Persuasion ◽  
The Individual ◽  
Social Level

Abstract Polarization of opinions is a societal threat. It involves psychological processes as well as group dynamics, a popular topic in statistical physics. However, the interaction between the within individual dynamics of attitude formation and across person polarization is rarely studied. By modelling individual attitudes as Ising networks of attitude elements, and approximating this behaviour by the cusp singularity, we developed a fundamentally new model of social dynamics. In this hierarchical model, agents behave either discretely or continuously depending on their attention to the issue. At the individual level, the model reproduces the mere thought effect and resistance to persuasion. At the social level, the model implies polarization and the persuasion paradox. We propose a new intervention for escaping polarization in bounded confidence models of opinion dynamics.

scholarly journals From behavioural analyses to models of collective motion in fish schools

2012 ◽  
Vol 2 (6) ◽  
pp. 693-707 ◽  
Author(s):  
Ugo Lopez ◽  
Jacques Gautrais ◽  
Iain D. Couzin ◽  
Guy Theraulaz
Keyword(s):  
Statistical Physics ◽  
Collective Motion ◽  
Theoretical Biology ◽  
Quantitative Agreement ◽  
Point Of View ◽  
School Level ◽  
Fish Schools ◽  
Individual Level ◽  
Modelling Assumptions ◽  
The Individual

Fish schooling is a phenomenon of long-lasting interest in ethology and ecology, widely spread across taxa and ecological contexts, and has attracted much interest from statistical physics and theoretical biology as a case of self-organized behaviour. One topic of intense interest is the search of specific behavioural mechanisms at stake at the individual level and from which the school properties emerges. This is fundamental for understanding how selective pressure acting at the individual level promotes adaptive properties of schools and in trying to disambiguate functional properties from non-adaptive epiphenomena. Decades of studies on collective motion by means of individual-based modelling have allowed a qualitative understanding of the self-organization processes leading to collective properties at school level, and provided an insight into the behavioural mechanisms that result in coordinated motion. Here, we emphasize a set of paradigmatic modelling assumptions whose validity remains unclear, both from a behavioural point of view and in terms of quantitative agreement between model outcome and empirical data. We advocate for a specific and biologically oriented re-examination of these assumptions through experimental-based behavioural analysis and modelling.

scholarly journals Predicting online behavioural responses to transcranial direct current stimulation in stroke patients with anomia

2021 ◽  
Author(s):  
Thomas Hope ◽  
Sasha Ondobaka ◽  
Haya Akkad ◽  
Davide Nardo ◽  
Jenny Crinion
Keyword(s):  
Model Performance ◽  
Reaction Times ◽  
Null Model ◽  
Therapeutic Interventions ◽  
Least Squares Regression ◽  
Stroke Patients ◽  
Massed Practice ◽  
Individual Level ◽  
High Doses ◽  
The Individual

BACKGROUND: Anomia, or difficulty naming common objects, is the most common, acquired impairment of language. Effective therapeutic interventions for anomia typically involve massed practice at high doses, requiring significant investment from patients and therapists. Aphasia researchers have increasingly looked to neurostimulation to accelerate these treatment effects, but the evidence behind this intervention is sparse and inconsistent.AIM: Here, we hypothesised that group-level neurostimulation effects might belie more systematic structure at the individual level. We sought to test the hypothesis by attempting to predict the immediate (online), individual-level behavioural effect of neurostimulation in patients with anomia.METHODS: 36 stroke patients, each with anomia at least 6 months post-onset, were asked to perform naming and judgement tasks both with concurrent neurostimulation and with sham stimulation. Using clinical, (pre-stimulation) behavioural and MRI data, and Partial Least Squares regression, we attempted to predict the effect of neurostimulation on accuracies and reaction times in both tasks. Model performance was assessed via cross-validation, and performances compared to that of a null model, which predicted the mean neurostimulation effects for all patients.RESULTS: Models derived from pre-stimulation data consistently out-performed the null model when predicting neurostimulation effects on accuracies and reaction times in both judgement and naming. Notably, we could predict declines in performance just as well as improvements.CONCLUSIONS: Inter-patient variation in online responses to neurostimulation is to some extent systematic and predictable. That declines in performance were just as predictable as improvements, implies that the effect of neurostimulation on performance in patients with anomia is unlikely to be a placebo. However, the online effect of the intervention appears to be just as likely to interfere with task performance, as it is to improve performance.

scholarly journals Emergent oscillations assist obstacle negotiation during ant cooperative transport

2016 ◽  
Vol 113 (51) ◽  
pp. 14615-14620 ◽  
Author(s):  
Aviram Gelblum ◽  
Itai Pinkoviezky ◽  
Ehud Fonio ◽  
Nir S. Gov ◽  
Ofer Feinerman
Keyword(s):  
Statistical Physics ◽  
Collective Motion ◽  
System Size ◽  
Tangential Direction ◽  
Critical System ◽  
Individual Level ◽  
Obstacle Circumvention ◽  
Quantitative Understanding ◽  
Physics Model ◽  
The Individual

Collective motion by animal groups is affected by internal interactions, external constraints, and the influx of information. A quantitative understanding of how these different factors give rise to different modes of collective motion is, at present, lacking. Here, we study how ants that cooperatively transport a large food item react to an obstacle blocking their path. Combining experiments with a statistical physics model of mechanically coupled active agents, we show that the constraint induces a deterministic collective oscillatory mode that facilitates obstacle circumvention. We provide direct experimental evidence, backed by theory, that this motion is an emergent group effect that does not require any behavioral changes at the individual level. We trace these relaxation oscillations to the interplay between two forces; informed ants pull the load toward the nest whereas uninformed ants contribute to the motion’s persistence along the tangential direction. The model’s predictions that oscillations appear above a critical system size, that the group can spontaneously transition into its ordered phase, and that the system can exhibit complete rotations are all verified experimentally. We expect that similar oscillatory modes emerge in collective motion scenarios where the structure of the environment imposes conflicts between individually held information and the group’s tendency for cohesiveness.

Differential Effects of Competence and Morality on Self-Esteem at the Individual and the Collective Level

2020 ◽  
Vol 51 (3) ◽  
pp. 183-198
Author(s):  
Wiktor Soral ◽  
Mirosław Kofta
Keyword(s):  
Self Esteem ◽  
Differential Effects ◽  
Individual Level ◽  
The Subject ◽  
The Individual

Abstract. The importance of various trait dimensions explaining positive global self-esteem has been the subject of numerous studies. While some have provided support for the importance of agency, others have highlighted the importance of communion. This discrepancy can be explained, if one takes into account that people define and value their self both in individual and in collective terms. Two studies ( N = 367 and N = 263) examined the extent to which competence (an aspect of agency), morality, and sociability (the aspects of communion) promote high self-esteem at the individual and the collective level. In both studies, competence was the strongest predictor of self-esteem at the individual level, whereas morality was the strongest predictor of self-esteem at the collective level.

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