The ability to synchronize both the movements and activity rhythms of many interacting individuals is a major component of the repertoire of collective behaviour in social species. Among the many social animals on Earth, ants have some of the most spectacular forms of synchronized behaviour because of their eusociality. One example of this impressive behavioral synchronization in ants is the so-called short-term activity cycle, where the workers inside a nest will move together in rhythmic pulses of activity that are separated by moments of collective rest and inactivity. There are many aspects of short-term activity cycles that are poorly understood. The first chapter of this thesis makes the case for why ants are a useful taxonomic group for studying social synchronization and introduces the phenomenon of ant short-term activity cycles. In chapter 2, I study intraspecific variation in short-term activity cycles and show that colonies’ queens, number of brood items, and number of workers all influence aspects of colony-level activity oscillations. In chapter 3, I show that colonies are capable of synchronizing despite noise in the behaviour of individual ants, and that colonies can modulate between multiple collective rhythms. In the same chapter, I also devised a model to study the role of noise more generally in excitable systems that have properties similar to those in ant colonies. Chapter 4 examined the effect of 24-hour light cycles on circadian activity, and I found that colonies kept in conditions with constant light or darkness had weaker circadian rhythms than colonies in an alternating light/dark regime. However, colonies’ short-term activity cycles were not affected by the external light regime. In chapter 5, I provide evidence that having synchronized rhythms of rest and activity provides a functional benefit for colonies: workers can, on average, more fully inspect the inside of the nest when activity is synchronized because inactive ants aggregate into piles that active ants have difficulty penetrating. In chapter 6, I recount a history of the research into synchronized and rhythmic activity patterns inside ant nests and consolidate the new results from the previous chapters with the existing literature to create an up-to-date review of what we currently know about short-term activity cycles. The work compiled here thereby sheds new light on an enigmatic form of synchronized behaviour in ants, one of the most ecologically important groups of animals on the planet. / Thesis / Doctor of Philosophy (PhD)

La vie en groupe est très répandue dans le monde animal. Ces agrégats peuvent être divers. Certains ne se forment que pendant les phases de repos des individus, d’autres sont maintenus pendant tout leur cycle de vie. De très nombreuses études ont porté sur les avantages et désavantages de la vie en groupe vis-à-vis des attaques des prédateurs. Parmi les coûts identifiés il y a notamment le fait qu’un groupe peut attirer plus facilement des prédateurs, parmi les bénéfices, citons l’augmentation du nombre d’individus qui peuvent détecter une menace et dès la probabilité d’une fuite efficace ou l’effet de dilution. Dans ce cas, la probabilité de se faire capturer lors d’une attaque diminue avec la taille du groupe. Mais dans ces exemples, c’est l’agrégat lui-même qui attire les prédateurs et est dès lors à l’origine des perturbations auxquelles il va être soumis. Il y a cependant d’autres perturbations qui peuvent affecter les agrégats entiers sans que ceux-ci en soient à l’origine. Ces perturbations peuvent être d’origine humaine comme l’urbanisation. Elles sont caractérisées par leur capacité à rendre par exemple un site d’agrégation moins attirant ou même inutilisable. Un exemple classique est celui d’un arbre qui est habituellement utilisé chaque soir par une bande d’oiseux et qui devient moins attirant suite aux bruits et lumières d’origine anthropique. Dans notre étude nous nous intéressons à ce type de perturbations et comment celles-ci affectent le comportement collectif, à court et long terme, d’agrégation. Le modèle retenu est la blatte américaine, Periplaneta americana, dont le site de repos (l’abri) est perturbé avec de la lumière lors de la phase de repos.Sur des temps courts (<10 min), nous avons étudié comment la taille des agrégats influence la fuite collective. Nous avons mis en évidence des phénomènes d’amplification et d’inhibition de la fuite. La probabilité de fuir augmente avec le nombre d’individus fuyant et diminue avec le nombre d’individus agrégés. Toujours à court terme nous avons montré que des blattes isolés ne présentent pas de personnalité (pas de différence interindividuelle) pour les différents paramètres mesurés lors de la fuite résultant d’une perturbation de l’abri. A long-terme (1 semaine) nous avons montré que le choix initial d’un site d’agrégation se maintenait malgré les perturbations imposées. Les blattes ne migrent que lentement que vers un autre abri non perturbé et ce malgré que suite à une perturbation une grande partie du groupe quitte temporairement l’abri. Sur cette longue durée, nous avons mis en évidence non seulement une personnalité pour chaque individu mais également une personnalité collective au niveau du groupe. Ces personnalités sont observées dans les dynamiques d’agrégation et désagrégation journalières et lors des fuites suite aux perturbations. / Doctorat en Sciences / info:eu-repo/semantics/nonPublished

Many animals including marine mammals and several seabird species dive in large groups, but the impacts that social interactions can have on diving behaviour are poorly understood. There are several potential benefits to social diving, such as access to social information or reduced predation risk. In this body of research I explore the use of social information by groups of diving animals by studying the behaviour of European shags (Phalacrocorax aristotelis) diving in “foraging rafts” in the Isles of Scilly. Using GPS tracking I establish where shags regularly forage in relation to bathymetry and areas where foraging rafts frequently formed. Using these data I show that the foraging ranges of different colonies overlap and that foraging ranges of individual shags are often predictable. This suggests that social information will be of less value while searching for foraging patches. However, using observational studies to further explore the conditions and areas in which foraging rafts formed, I show that advantages such as anti-predation or hydrodynamic benefits are unlikely to be the main drivers of rafting behaviour in the Scillies. I therefore suggest that access to social information from conspecifics at a foraging patch may be one of the main benefits diving in groups. Using a dynamic programming model I show that individuals diving in a group benefit from using social information, even when unable to assess conspecific foraging success. Finally I use video analysis to extract the positions and diving behaviour of individuals within a foraging raft and compare this to simulated data of collective motion and diving behaviour. The results of these studies indicate that an individual being able to utilise dives of conspecifics to inform their own diving decisions may be one of the main advantages of social diving.

The emergence of collective patterns from repeated local interactions between individuals is a common feature to most living systems, spanning a variety of scales from cells to animals and humans. Subjects of this thesis are two aspects of emergent complexity in living systems: collective movement and transport network formation. For collective movement, this thesis studies the role of movement-mediated information transfer in fish decision-making. The second project on collective movement takes inspiration from granular media and soft mode analysis and develops a new approach to describe the emergence of collective phenomena from physical interactions in extremely dense crowds. As regards transport networks, this thesis proposes a model of network growth to extract simple, biologically plausible rules that reproduce topological properties of empirical ant trail networks.  In the second project on transport networks, this thesis starts from the simple rule of “connecting each new node to the closest one”, that describes ants building behavior, to study how balancing local building costs and global maintenance costs influences the growth and topological properties of transport networks. These projects are addressed through a modeling approach and with the aim of identifying minimal sets of basic mechanisms that are most likely responsible of large-scale complex patterns. Mathematical models are always based on empirical observations and are, when possible, compared to experimental data.

<p>This dissertation aims to present a structured overview of the state-of-the-art in cooperative robotics research. As we illustrate in this dissertation, there are several interesting aspects that draws attention to the field, among which 'Life Sciences' and 'Applied AI' are emphasized. We analyse the key concepts and main research issues within the field, and discuss its relations to other disciplines, including cognitive science, biology, artificial life and engineering. In particular it can be noted that the study of collective robot behaviour has drawn much inspiration from studies of animal behaviour. In this dissertation we also analyse one of the most attractive research areas within cooperative robotics today, namely RoboCup. Finally, we present a hierarchy of levels and mechanisms of cooperation in robots and animals, which we illustrate with examples and discussions.</p>

In recent years the G8 and G20 Summits have become important sites of protest and conflict. Extensive planning by police and protesters have transformed the public meaning of these yearly assemblies into large-scale events characterized by what many see as threats to public order. The summits have also provided a world-stage for the economically and racially disadvantaged as well as globalized free trade dissenters to voice their resistance and opposition. At the same time, police have been placed on the opposite side of the conflict, ordered to “control the masses.” This conflict situation can sometimes lead to collective violence, especially on behalf of the police. In attempting to explain the police collective violence witnessed at the G8/G20 protests in Toronto in June of 2010, Neil Smelser’s (1962) value-added model of collective behaviour can be employed. This model demonstrates how processes involving structural conduciveness, structural strain, the spread of a generalized belief, the mobilization of participants and finally the utilization of social control can lead to an event such as collective violence. Recent revisions to the value-added argument by Fine (1997) have shifted attention away from the functionalist assumptions of the model and toward a more social constructionist stance. Thus, for Fine, belief itself does not create action. Rather, the use of the belief by claimsmakers can lead to a call to action, through media or other outlets. Finally, Randall Collins’s (2008) theory of forward panic is useful for illustrating the finer details of precisely how police mobilize for violence. In order to analyze the police collective violence witnessed over the weekend, a combination of participant observation, semi-structured interviews and ethnographic content analysis methods were employed. The findings support that because of the placement of the G8/G20 meetings, the conflicting relationship between the police and the protesters and the construction of the protesters as troublemakers, meant to be approached with suspicion, the police were able to overcome the tense conflict situation and attack the protesters. I conclude by suggesting a community-policing model for future protest situations. / Thesis (Master, Sociology) -- Queen's University, 2011-06-30 11:36:35.115

Navigating the physical world may present only a small fraction of the challenges faced by social animals. Sociality brings with it numerous benefits, including access to important information that may have otherwise been harder to come by. However, almost every aspect of these apparent benefits may also entail additional cognitive challenges, including how to interpret signals from conspecifics, who to attend to, and how to incorporate knowledge about signallers when deciding how to respond. One approach to understanding the cognitive abilities associated with social function is to investigate social species that take part in potentially costly group behaviours, where individual decisions must be made in a social context. In this thesis I explore how jackdaws (Corvus monedula), a highly sociable corvid species, use acoustic information to coordinate collective anti-predator responses. In Chapter Two I showed using playback experiments that the magnitude of collective responses to anti-predator recruitment calls known as “scolding” calls depends on the identity of the caller, with larger responses to familiar colony members than unfamiliar individuals. In Chapter Three I then used habituation-dishabituation experiments to show that this vocal discrimination operates at the level of the individual, with jackdaws discriminating between the calls of different conspecifics, regardless of their level of familiarity. In Chapter Four, I examined whether aspects of call structure conveyed information about threat levels. Here, I found that high rates of scolding calls were associated with elevated threats, and playback experiments suggested that this information might result in larger group responses. The finding that jackdaws are capable of mediating their response to alarm calls based on the identity of the individual caller, and on structural variation in call production, raised the question of whether jackdaws employed similar forms discrimination between acoustic cues made by predators in their environment. I investigated this in Chapter Five, using playback experiments to show that jackdaws responded not only to the vocalisations of resident predators, but that this ability extended to novel predators, and that responsiveness was mediated by the phase of the breeding season in which predators were heard. Together, these findings provide insights in to how discrimination among acoustic cues can mediate group behaviour in species that respond collectively to threats.

This dissertation aims to present a structured overview of the state-of-the-art in cooperative robotics research. As we illustrate in this dissertation, there are several interesting aspects that draws attention to the field, among which 'Life Sciences' and 'Applied AI' are emphasized. We analyse the key concepts and main research issues within the field, and discuss its relations to other disciplines, including cognitive science, biology, artificial life and engineering. In particular it can be noted that the study of collective robot behaviour has drawn much inspiration from studies of animal behaviour. In this dissertation we also analyse one of the most attractive research areas within cooperative robotics today, namely RoboCup. Finally, we present a hierarchy of levels and mechanisms of cooperation in robots and animals, which we illustrate with examples and discussions.

The work presented herein focuses on the design of distributed autonomous controllers for collective behaviour of Micro-unmanned Aerial Vehicles (MAVs). Two alternative approaches to this topic are introduced: one based upon the Evolutionary Robotics (ER) paradigm, the other one upon flocking principles. Three computer simulators have been developed in order to carry out the required experiments, all of them having their focus on the modelling of fixed-wing aircraft flight dynamics. The employment of fixed-wing aircraft rather than the omni-directional robots typically employed in collective robotics significantly increases the complexity of the challenges that an autonomous controller has to face. This is mostly due to the strict motion constraints associated with fixed-wing platforms, that require a high degree of accuracy by the controller. Concerning the ER approach, the experimental setups elaborated have resulted in controllers that have been evolved in simulation with the following capabilities: (1) navigation across unknown environments, (2) obstacle avoidance, (3) tracking of a moving target, and (4) execution of cooperative and coordinated behaviours based on implicit communication strategies. The design methodology based upon flocking principles has involved tests on computer simulations and subsequent experimentation on real-world robotic platforms. A customised implementation of Reynolds’ flocking algorithm has been developed and successfully validated through flight tests performed with the swinglet MAV. It has been notably demonstrated how the Evolutionary Robotics approach could be successfully extended to the domain of fixed-wing aerial robotics, which has never received a great deal of attention in the past. The investigations performed have also shown that complex and real physics-based computer simulators are not a compulsory requirement when approaching the domain of aerial robotics, as long as proper autopilot systems (taking care of the ”reality gap” issue) are used on the real robots.

In this thesis, we used the American cockroach study the relationship between animal personality and collective behaviour. These questions do not only regard domiciliary cockroaches or insects; in fact, the questions we discuss here have a large scope and concern most of the known gregarious species distributed in several taxa. One of our aims is to develop general tools, methods and analyses that could be used for the study of collective behaviour.We show evidence of personality in several behavioural traits and different contexts in the American cockroach. These behavioural differences were observed in a context without social interactions during the daytime (isolated condition) and nighttime (solitary exploration behaviour) and in a social context (rate of joining a shelter and sheltering time). Based on the short-term experiments, this personality can be understood as differences in the probability of joining a shelter. We show that the behavioural variability existing in a population of domiciliary cockroaches is very high. The composition of personalities within a group can lead to group personality – consistent differences in group behaviour. For instance, groups composed of different behavioural profiles show different collective dynamics. Regarding the long-term experiments, our results show that the individuals that were aggregated at a site that was repeatedly disturbed by a lighting stimulus during their resting period showed slow migration to a new shelter, which allowed the initial aggregation site to remain the site of choice for a few days. Moreover, the disturbance regime did not influence the group's global activity rhythm. At the individual level, we observed interindividual differences (personalities) in terms of their position prior to the disturbance but not for the different steps of the fleeing behaviour itself. In addition, we show that thigmotaxis affects the reaction time to the disturbance: individuals near the walls of the shelter react more slowly thanindividuals in the centre. Finally, an approach coupling modelling and experimental data shows that behavioural variability plays a secondary role during migration dynamics, thus highlighting the plasticity of personality traits depending on the context. / Un des comportements collectifs les plus répandus, qu’il s’agisse de vertébrés (mammifères, oiseaux, poissons), d’insectes ou encore de bactéries, est la tendance des individus à se regrouper. Les causes proximales de ces rassemblements ou agrégats, c'est-à-dire les mécanismes à leur origine, ont retenu moins d’attention que l’étude des causes ultimes. De plus, dans la plupart des études portant sur les processus d’agrégation, notamment chez notre organisme modèle, la blatte, la diversité des comportements individuels est souvent sous-estimée ou ignorée. L’objectif de cette thèse est l’étude du rôle des différences interindividuelles, également connues comme personnalité animale ou syndromes comportementales, dans les processus de prise de décision collective et notamment la formation des agrégats.Pour cela, nous avons utilisé des groupes de mâles de la blatte américaine Periplaneta americana. Ces insectes peuvent s’agréger dans un ou plusieurs abris et présenter des différences dans leur réponse au milieu, aux conspécifiques et dans le partage de l’information. Dans le cadre de prises de décisions collectives, nous avons mis en évidence une personnalité individuelle mais également au niveau du groupe. Celles-ci se manifestent dans la recherche d’un abri dont certains individus jouent un rôle clef. Nous avons montré que les groupes présentent une stabilité qui est observable au niveau de la dynamique d'agrégation et qui dépend de la distribution des personnalités au sein de ceux-ci. De plus, nous remarquons que ces différences de personnalités au sein des groupes affectent la prise de décision collective, notamment la vitesse du choix et le nombre total d’individus abrités. De manière surprenante, la composition des groupes n’affecte pas la probabilité que ceux-ci atteignent un consensus: la majorité des blattes étant agrégées sous le même abri.Concernant les influences croisées entre l’effet sociale et la personnalité des blattes, nous montrons que les effets sociaux tendent à supprimer les différences inter-individuelles et créent une corrélation entre le comportement de chaque individu et le comportement du groupe. De plus, nous observons que la présence de différentes personnalités dans un groupe augmente les amplifications sociales, celles-ci étant dues aux interactions entre les membres du groupe. Finalement, nous abordons la question du rôle de la personnalité sur le comportement de fuite lors des perturbations lumineuses et sur la dynamique d’émigration quand le site de repos est régulièrement perturbé. Nous avons montré l’existence de personnalités exprimées pendant la phase active nocturne et de différences interindividuelles au niveau du thigmotactisme pendant la journée (phase passive de repos et d’agrégation). Curieusement, ces différences inter-individuelles ne sont pas observées lors du comportement de fuite et au niveau de la dynamique global d’émigration. Dans la dernière partie de notre thèse, nous discutons, en particulier, des synergies et des conflits entre les différentes personnalités et les dynamiques collectives et avançons l’hypothèse que les phénomènes que nous avons mis en évidence sont partagés par de nombreuses espèces grégaires. / Doctorat en Sciences / info:eu-repo/semantics/nonPublished