56 research outputs found
Experimental analysis and modelling of the behavioural interactions underlying the coordination of collective motion and the propagation of information in fish schools
Les bancs de poissons sont des entités pouvant regrouper plusieurs milliers d'individus qui se déplacent de façon
synchronisée, dans un environnement sujet à de multiples perturbations, qu'elles soient endogènes (e.g. le départ soudain
d'un congénère) ou exogènes (e.g. l'attaque d'un prédateur). La coordination de ces bancs de poissons, décentralisée, n'est
pas encore totalement comprise. Si les mécanismes sous-jacents aux interactions sociales proposés dans des travaux
précédents reproduisent qualitativement les structures collectives observées dans la nature, la quantification de ces
interactions et l'accord quantitatif entre ces mesures individuelles et les motifs collectifs sont encore rares dans les
recherches récentes et forment l'objet principal de cette thèse.
L'approche de ce travail repose sur une étroite combinaison entre les méthodes expérimentales et de modélisation dans
l'objectif de découvrir les liens entre les comportements individuels et les structures observées à l'échelle collective.
Nous avons caractérisé et quantifié les interactions et mécanismes à l'origine, d'abord, de la coordination des individus
dans les bancs de poissons et, ensuite, de la propagation d'information, quand le groupe subit une perturbation endogène ou
exogène. Ces travaux, tous réalisés en étudiant la même espèce de poisson d'eau douce, le nez-rouge (Hemigrammus
rhodostomus), ont mobilisĂ© une diversitĂ© de mĂ©thodes expĂ©rimentales, d'analyses statistique et de modĂ©lisation, Ă
l'interface de l'Ă©thologie, de la physique statistique et des sciences computationnelles.Fish schools are systems in which thousands of individuals can move in a synchronised manner in a changing environment, with
endogenous perturbations (e.g. when a congener leaves the group) or exogenous (e.g. the attack of a predator). The
coordination of fish schools, decentralised, is not completely understood yet. If the mechanisms underlying social
interactions discussed in previous studies qualitatively match the social patterns observed in nature, the quantification of
these interactions and the quantitative match between individual measurements and collective patterns are still sparse in
recent works and are the main focus of this thesis.
This work combines closely experimental and modelling methods in order to investigate the links between the individual
behaviours and the patterns observed at the collective scale. We have characterised and quantified the interactions and
mechanisms at the origin of, first, the coordination of individuals in fish schools and, second, the propagation of
information, when the group is under endogenous or exogenous perturbations. This thesis focuses on one freshwater fish
species, the rummy-nose tetra (Hemigrammus rhodostomus), and is the result of a diversity of experimental methods,
statistical analyses and modelling, at the interface of ethology, statistical physics and computational sciences
Informative and misinformative interactions in a school of fish
It is generally accepted that, when moving in groups, animals process
information to coordinate their motion. Recent studies have begun to apply
rigorous methods based on Information Theory to quantify such distributed
computation. Following this perspective, we use transfer entropy to quantify
dynamic information flows locally in space and time across a school of fish
during directional changes around a circular tank, i.e. U-turns. This analysis
reveals peaks in information flows during collective U-turns and identifies two
different flows: an informative flow (positive transfer entropy) based on fish
that have already turned about fish that are turning, and a misinformative flow
(negative transfer entropy) based on fish that have not turned yet about fish
that are turning. We also reveal that the information flows are related to
relative position and alignment between fish, and identify spatial patterns of
information and misinformation cascades. This study offers several
methodological contributions and we expect further application of these
methodologies to reveal intricacies of self-organisation in other animal groups
and active matter in general
Disentangling and modeling interactions in fish with burst-and-coast swimming reveal distinct alignment and attraction behaviors
We combine extensive data analyses with a modeling approach to measure,
disentangle, and reconstruct the actual functional form of interactions
involved in the coordination of swimming in Rummy-nose tetra (Hemigrammus
rhodostomus). This species of fish performs burst-and-coast swimming behavior
that consists of sudden heading changes combined with brief accelerations
followed by quasi-passive, straight decelerations. We quantify the spontaneous
stochastic behavior of a fish and the interactions that govern wall avoidance
and the attraction and alignment to a neighboring fish, the latter by
exploiting general symmetry constraints for the interactions. In contrast with
previous experimental works, we find that both attraction and alignment
behaviors control the reaction of fish to a neighbor. We then exploit these
results to build a model of spontaneous burst-and-coast swimming and
interactions of fish, with all parameters being estimated or directly measured
from experiments. This model quantitatively reproduces the key features of the
motion and spatial distributions observed in experiments with a single fish and
with two fish. This demonstrates the power of our method that exploits large
amounts of data for disentangling and fully characterizing the interactions
that govern collective behaviors in animals groups. Moreover, we introduce the
notions of "dumb" and "intelligent" active matter and emphasize and clarify the
strong differences between them.Comment: Supplementary Information (PDF text + 5 videos) can be downloaded at
http://www.lpt.ups-tlse.fr/spip.php?action=acceder_document&arg=2240&cle=f7d43896e78b1b15dff009dc7769eac3c956c76a&file=zip%2FSI_Web.zi
On collective bandit behaviour
The collective decision process of Gambusia affinis (the mosquitofish) is investigated from the standpoint of online machine learning algorithms. A new algorithm, the Collaborative Exp3 algorithm, is derived from the adversarial bandits framework to model how groups of fish make collective decisions leading to consensus. Thanks to maximum likelihood estimation, parameters are tuned and comparisons between data and algorithm performances are addressed. This work provides promising results in the scope of recovering information transfer within fish groups as well as to understand the individual mechanisms involved in the collective decision process. It is the first published approach to connect online machine learning algorithms with data, hence bridging a gap between theory and biological practice
Analyse expérimentale et modélisation des interactions comportementales impliquées dans la coordination des déplacements collectifs et la propagation d'information des bancs de poisson
Fish schools are systems in which thousands of individuals can move in a synchronised manner in a changing environment, with endogenous perturbations (e.g. when a congener leaves the group) or exogenous (e.g. the attack of a predator). The coordination of fish schools, decentralised, is not completely understood yet. If the mechanisms underlying social interactions discussed in previous studies qualitatively match the social patterns observed in nature, the quantification of these interactions and the quantitative match between individual measurements and collective patterns are still sparse in recent works and are the main focus of this thesis. This work combines closely experimental and modelling methods in order to investigate the links between the individual behaviours and the patterns observed at the collective scale. We have characterised and quantified the interactions and mechanisms at the origin of, first, the coordination of individuals in fish schools and, second, the propagation of information, when the group is under endogenous or exogenous perturbations. This thesis focuses on one freshwater fish species, the rummy-nose tetra (Hemigrammus rhodostomus), and is the result of a diversity of experimental methods, statistical analyses and modelling, at the interface of ethology, statistical physics and computational sciences.Les bancs de poissons sont des entités pouvant regrouper plusieurs milliers d'individus qui se déplacent de façon synchronisée, dans un environnement sujet à de multiples perturbations, qu'elles soient endogènes (e.g. le départ soudain d'un congénère) ou exogènes (e.g. l'attaque d'un prédateur). La coordination de ces bancs de poissons, décentralisée, n'est pas encore totalement comprise. Si les mécanismes sous-jacents aux interactions sociales proposés dans des travaux précédents reproduisent qualitativement les structures collectives observées dans la nature, la quantification de ces interactions et l'accord quantitatif entre ces mesures individuelles et les motifs collectifs sont encore rares dans les recherches récentes et forment l'objet principal de cette thèse. L'approche de ce travail repose sur une étroite combinaison entre les méthodes expérimentales et de modélisation dans l'objectif de découvrir les liens entre les comportements individuels et les structures observées à l'échelle collective. Nous avons caractérisé et quantifié les interactions et mécanismes à l'origine, d'abord, de la coordination des individus dans les bancs de poissons et, ensuite, de la propagation d'information, quand le groupe subit une perturbation endogène ou exogène. Ces travaux, tous réalisés en étudiant la même espèce de poisson d'eau douce, le nez-rouge (Hemigrammus rhodostomus), ont mobilisé une diversité de méthodes expérimentales, d'analyses statistique et de modélisation, à l'interface de l'éthologie, de la physique statistique et des sciences computationnelles
On collective bandit behaviour
The collective decision process of Gambusia affinis (the mosquitofish) is investigated from the standpoint of online machine learning algorithms. A new algorithm, the Collaborative Exp3 algorithm, is derived from the adversarial bandits framework to model how groups of fish make collective decisions leading to consensus. Thanks to maximum likelihood estimation, parameters are tuned and comparisons between data and algorithm performances are addressed. This work provides promising results in the scope of recovering information transfer within fish groups as well as to understand the individual mechanisms involved in the collective decision process. It is the first published approach to connect online machine learning algorithms with data, hence bridging a gap between theory and biological practice
Experimental analysis and modelling of the behavioural interactions underlying the coordination of collective motion and the propagation of information in fish schools
Gezamenlijke coördinatie van bewegingen is alomtegenwoordig in vissen. Grote visscholen kunnen duizenden tot miljoenen dieren bevatten. Het is echter onbekend welke locale gedragsregels deze collective gedragspatronen aansturen. In dit proefschrift onderzoeken we in de roodneuszalm (Hemigrammus rhodostomus), welke mechanismen bijdragen aan de coördinatie van hun school en de transmissie van informatie. Om de samenhang tussen individueel gedrag en collectieve patronen te achterhalen, combineren we empirisch onderzoek en computermodellen in onze benadering
Trajectories for groups of 1 fish
Trajectories for groups of 1 fis
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