Inter-individual Interactions Research Articles

Associations and the role of affiliative, agonistic, and socio-sexual behaviors among common bottlenose dolphins (Tursiops truncatus)

Little is known about the specific behavioral exchanges that occur on a day-to-day basis between dyads of common bottlenose dolphins (Tursiops truncatus). This study assesses the proportion of time dyads spend in proximity (within ∼2m) and the proportion of time spent in affiliative, agonistic, or socio-sexual contexts within and between age/sex dolphin pairings to better understand their social relationships. Observations of bottlenose dolphins housed at the Roatan Institute of Marine Sciences provided 10.5h of underwater footage from which to examine association coefficients and inter-individual interactions. These data suggest similar patterns to previous studies on bottlenose dolphins: mother-calf dyads shared the highest coefficients of association, followed by male-male, female-female, and male-female dyads. Four classes of association coefficients were defined for the population including low, medium, medium-high and high. This study is the first to quantitatively assess association patterns concurrently with affiliative, agonistic, and socio-sexual behaviors for bottlenose dolphins. The predominant relationships were affiliative.

Switching hierarchical leadership mechanism in homing flight of pigeon flocks

To explore the fascinating inter-individual interaction mechanism governing the abundant biological grouping behaviors, more and more efforts have been devoted to collective motion investigation in recent years. Therein, bird flocking is one of the most intensively studied behaviors. A previous study (Nagy M. et al., Nature, 464 (2010) 890.) claims the existence of a well-defined hierarchical structure in pigeon flocks, which implies that a multi-layer leadership network leads to the occurrence of highly coordinated pigeon flock movements. However, in this study, by using high-resolution GPS data of homing flight of pigeon flocks, we reveal an explicit switching hierarchical mechanism underlying the group motions of pigeons. That is, a pigeon flock has a long-term leader for smooth moving trajectories, whereas the leading tenure passes to a temporary one upon sudden turns or zigzags. Therefore, the present observation helps explore more deeply into the principle of a huge volume of bird flocking dynamics. Meanwhile, from the engineering point of view, it may shed some light onto industrial multi-robot coordination and unmanned air vehicle formation control.

Ontogeny and Sexual Differences in Swimming Proximity to Conspecifics in Response to Visual Cues in Medaka Fish.

Adult medaka fish (Oryzias latipes) exhibit complex social behaviors that depend mainly on visual cues from conspecifics. The ontogeny of visually-mediated social behaviors from larval/juvenile to adult medaka fish, however, is unknown. In the present study, we established a simple behavioral paradigm to evaluate the swimming proximity to conspecifics based on visual cues in an inter-individual interaction of two medaka fish throughout life. When two fish were placed separately in a cylindrical tank with a concentric transparent wall, the two fish maintained close proximity to each other. A normal fish inside the tank maintained proximity to an optic nerve-cut fish outside of the tank, while the converse was not true. This behavioral paradigm enabled us to quantify visually-induced motivation of a single fish inside the tank. The proximity was detected from larval/juvenile to adult fish. Larval fish, however, maintained close proximity not only to conspecifics, but also to heterospecifics. As the growth stage increased, the degree of proximity to heterospecifics decreased, suggesting that shoaling preferences toward conspecifics and/or visual ability to recognize conspecifics is refined and established according to the growth stage. Furthermore, the proximity of adult female fish was affected by their reproductive status and social familiarity. Only before spawning, adult females maintained closer proximity to familiar males rather than to unfamiliar males, suggesting that proximity was affected by familiarity in a female-specific manner. This simple behavioral paradigm will contribute to our understanding of the neural basis of the development of visually-mediated social behavior using medaka fish.

Swarming of heterogeneous multi-agent systems with periodically intermittent control

This paper investigates a class of heterogeneous swarming systems with periodically intermittent control. It is assumed that agents in the network are nonidentical and potential functions are heterogeneous. Each agent is assumed to obtain information from the leader and the neighbors only on a series of periodically time intervals. The dynamics of the swarm members are affected by inter-individual interactions and the environment. In addition, we consider the first-order integrator system with a class of attraction/repulsion functions. Some sufficient conditions are provided to guarantee exponential stability of the whole system. Although the information from the leader agent and the neighbors is not continuous, all follower agents can track the leader agent in certain error range. A numerical example is shown to illustrate the validity of the above theoretical result.

Commentaries on Viewpoint: A call for research to assess and promote functional resilience in astronaut crews

Commentaries on Viewpoint: A call for research to assess and promote functional resilience in astronaut crews

Mapping areas of spatial-temporal overlap from wildlife tracking data.

BackgroundThe study of inter-individual interactions (often termed spatial-temporal interactions, or dynamic interactions) from remote tracking data has focused primarily on identifying the presence of such interactions. New datasets and methods offer opportunity to answer more nuanced questions, such as where on the landscape interactions occur. In this paper, we provide a new approach for mapping areas of spatial-temporal overlap in wildlife from remote tracking data. The method, termed the joint potential path area (jPPA) builds from the time-geographic movement model, originally proposed for studying human movement patterns.ResultsThe jPPA approach can be used to delineate sub-areas of the home range where inter-individual interaction was possible. Maps of jPPA regions can be integrated with existing geographic data to explore landscape conditions and habitat associated with spatial temporal-interactions in wildlife. We apply the jPPA approach to simulated biased correlated random walks to demonstrate the method under known conditions. The jPPA method is then applied to three dyads, consisting of fine resolution (15 minute sampling interval) GPS tracking data of white-tailed deer (Odocoileus virginianus) collected in Oklahoma, USA. Our results demonstrate the ability of the jPPA to identify and map jPPA sub-areas of the home range. We show how jPPA maps can be used to identify habitat differences (using percent tree canopy cover as a habitat indicator) between areas of spatial-temporal overlap and the overall home range in each of the three deer dyads.ConclusionsThe value of the jPPA approach within current wildlife habitat analysis workflows is highlighted along with its simple and straightforward implementation and interpretation. Given the current emphasis on remote tracking in wildlife movement and habitat research, new approaches capable of leveraging both the spatial and temporal information content contained within these data are warranted. We make code (in the statistical software R) for implementing the jPPA approach openly available for other researchers.Electronic supplementary materialThe online version of this article (doi:10.1186/s40462-015-0064-3) contains supplementary material, which is available to authorized users.

Chaotic patterns in the discrete-time dynamics of social foraging swarms with attractant–repellent profiles: an analysis

This article investigates the chaotic dynamical characteristics of a discrete-time social foraging swarm model in which the individuals move in a d-dimensional space according to an attractant/repellent or a nutrient profile. The collective behavior of the swarm model results from the balance between inter-individual interactions and the simultaneous interactions of the swarm members with their environment. Analysis undertaken in the paper indicates that chaos can be introduced into the system by tuning the parameters of the mutual attraction-repulsion function and the attractant–repellent profiles of the swarm dynamics [as given in Eq. (1)]. Ranges of different parameters to ensure sufficient condition for chaotic characteristics have been determined. Apart from chaos, stable and limit cyclic behaviors are also demonstrated for various parameter ranges. Effect of different attractant/repellent gradient profiles on the mean swarm trajectory in the presence of chaos has also been studied. Presence of chaos is determined by means of the Lyapunov exponent. Results obtained from the theoretical analysis are validated through comprehensive simulations.

Information criteria and approximate Bayesian computing for agent-based modelling in ecology: New tools to infer on Individual-level processes

Agent or individual based models (ABMs) are computer simulation tools to represent complex systems where the unique autonomous individuals constituting the system interact, adapt or evolve. In ecology, ABMs have been applied to analyse the influence of individual variability, spatial interactions, development, behaviour, learning or genetic variability on group, population or community dynamics [1]. During the last 20 years, the approach of pattern-oriented modelling (POM) has been helping in making the use of ABMs more robust and reliable [2]. Two main elements of POM are a) ``inverse modelling'' to reduce parameter uncertainty and b) ``strong inferences'' to test how well alternative model versions changing in certain individual-level processes are at explaining multiple patterns observed at the population and/or community level. The latter has many parallels to model selection procedures in statistical modelling ( ``mutlimodel inference'' [3]). The inverse modelling borrows also concept and tools from statistics to fit unknown or uncertain parameters to real-world data. With the development of approximate Bayesian computing (ABC) in ecology [4] some propositions were made to use ABC in ABMs [5]. Bridging the two main elements of POM, an information criterion was proposed [6] that borrows concept of ABC such as Markov Chains Monte Carlo simulations without likelihood functions and multimodel inference in Bayesian context. This criterion (POMIC for pattern-oriented modelling information criterion) was applied in the original proposition paper to forest growth simulations to infer on individual tree growth function. Recently, it was applied to locust to infer on individual behaviour at hatching [7]. These kinds of cryptic processes (tree individual growth or animals' behaviour during first hours) can typically be analysed following few isolated individuals in natural or experimental conditions. However, in the context of inter-individual interactions, experimental designs to infer on how the interactions modify individual responses are hard, if not impossible to elaborate. Using population or group level data to fit ABMs and infer on the potential individual process with different ABMs version is then a way of overpassing these problems. However, the question of ABMs complexity (essential in statistical model selection procedures) needs to be addressed. The POMIC proposition includes a complexity measure and makes it therefore an interesting tool to infer on cryptic individual-level processes of complex systems. (Texte integral)

Ecology of information: social transmission dynamics within groups of non-social insects.

While many studies focus on how animals use public information, the dynamics of information spread and maintenance within groups, i.e. the 'ecology of information', have received little attention. Here we use fruitflies trained to lay eggs on specific substrates to implement information into groups containing both trained and untrained individuals. We quantify inter-individual interactions and then measure the spread of oviposition preference with behavioural tests. Untrained individuals increase their interactive approaches in the presence of trained individuals, and the oviposition preference transmission is directly proportional to how much trained and untrained individuals interact. Unexpectedly, the preference of trained individuals to their trained oviposition substrate decreases after interactions with untrained individuals, leading to an overall informational loss. This shows that social learning alone is not enough to support informational stability.

Multi-pheromone ant Colony Optimization for Socio-cognitive Simulation Purposes

We present an application of Ant Colony Optimisation (ACO) to simulate socio-cognitive features of a population. We incorporated perspective taking ability to generate three different proportions of ant colonies: Control Sample, High Altercentricity Sample, and Low Alter-centricity Sample. We simulated their performances on the Travelling Salesman Problem and compared them with the classic ACO. Results show that all three ‘cognitively enabled’ ant colonies require less time than the classic ACO. Also, though the best solution is found by the classic ACO, the Control Sample finds almost as good a solution but much faster. This study is offered as an example to illustrate an easy way of defining inter-individual interactions based on stigmergic features of the environment.

Route-dependent switch between hierarchical and egalitarian strategies in pigeon flocks.

The mechanisms that underlie fascinating inter-individual interactions among animal groups have attracted increasing attention from biologists, physicists, and system scientists. There are two well-known types of interaction patterns: hierarchical and egalitarian. In the former type, individuals follow their leaders, whereas they follow their neighbors in the latter. Using high-resolution spatiotemporal data derived from the free flights of a flock of pigeons, we show that pigeon flocks actually adopt a mode that switches between the two aforementioned strategies. To determine its flight direction, each pigeon tends to follow the average of its neighbors while moving along a smooth trajectory, whereas it switches to follow its leaders when sudden turns or zigzags occur. By contrast, when deciding how fast to fly, each pigeon synthesizes the average velocity of its neighbors. This switching mechanism is promising for possible industrial applications in multi-robot system coordination, unmanned vehicle formation control, and other areas.

Particle swarm optimization with scale-free interactions.

The particle swarm optimization (PSO) algorithm, in which individuals collaborate with their interacted neighbors like bird flocking to search for the optima, has been successfully applied in a wide range of fields pertaining to searching and convergence. Here we employ the scale-free network to represent the inter-individual interactions in the population, named SF-PSO. In contrast to the traditional PSO with fully-connected topology or regular topology, the scale-free topology used in SF-PSO incorporates the diversity of individuals in searching and information dissemination ability, leading to a quite different optimization process. Systematic results with respect to several standard test functions demonstrate that SF-PSO gives rise to a better balance between the convergence speed and the optimum quality, accounting for its much better performance than that of the traditional PSO algorithms. We further explore the dynamical searching process microscopically, finding that the cooperation of hub nodes and non-hub nodes play a crucial role in optimizing the convergence process. Our work may have implications in computational intelligence and complex networks.

Boceprevir (BOC) and Telaprevir (TPV) therapeutic drug monitoring in HCV and HIV-HCV infected patients treated with triple therapy Ribavirine/Peg-interferon/Boceprevir or Telaprevir: impact of the antiretroviral (ARV) treatment

BOC and TPV are potent NS3/4A protease inhibitors for the treatment of chronic hepatitis C (HCV) genotype 1 infection. BOC and TPV are both substrates and strong inhibitors of the CYP3A, therefore presenting a wide interindividual pharmacokinetic variability and multiple drug interactions especially with ARV such as lopinavir/r, darunavir/r or efavirenz, thus restricting options for concomitant ARV therapy. We evaluated plasma concentrations of coinfected and monoinfected patients treated with BOC and TPV and the PK data of patients treated with non recommended ARV.

Between Emancipatory Practice and Disciplinary Interventions: Empowerment and Contemporary Social Normativity

Over the last decades, empowerment has become one of the defining concepts of twenty-first-century social work practice. Many studies have set out to show its benefits, highlighting a positive view of individuals and their ability to instigate sustainable change in their life and/or community. The concept, however, has been more often praised than it has been critiqued. This article aims to add to critical works on empowerment in analysing its implications from the point of view of contemporary social normativity, informed by the works of Ehrenberg (2010), Rose (1996) and Foucault (1979). In this perspective, we suggest that the ever-present injunctions to autonomy and individual responsibility can serve simultaneously as a goal and as means to empowerment-centred interventions. The line between emancipatory practices and discipline can thus be thin. By postulating that social work extends beyond inter-individual interactions, the relationship between individuals and normative injunctions becomes a highly interesting subject of study that would prove fruitful in future empirical studies.

Coordination tendencies are shaped by attacker and defender interactions with the goal and the ball in futsal

This study examined how the location of the goal and ball constrained the interpersonal coordination tendencies emerging of attacker-defender dyadic systems in team sports. Additionally, we analysed how the positioning of defenders constrained the emergent coordination tendencies between the ball carrier and supporting teammates. To investigate these tendencies in team sports, ten futsal games were filmed to observe inter-individual interactions. Movement trajectories of players and ball were digitized during 52 outfield attacker-defender interactions involving thirteen goal-scoring sequences. Relative phase was used as a measure to express participant coordination tendencies in these dyadic systems (in-phase or symmetry – 0°; anti-phase or anti-symmetry – 180°). Stable in-phase patterns of coordination emerged between specific values of an attacker’s distances to defenders and the goal (19% frequency from 0° to 29° of phase relations) and between specific values of distances of ball carriers to defenders and teammates (14% frequency from 0° to 29° of phase relations). A stable pattern of coordination of −60° emerged between values of an attacker’s distances to defenders and the ball (18% frequency from 0° to 29° of phase relations). Distances of attackers to the goal and ball, and distances of ball carriers to defenders, seemed to be coupled in a specific manner to guide interpersonal coordination tendencies between players during competitive performance in the team sport of futsal.

Antiplatelet Agents in Diabetic Patients: Clinical Advances and Remaining Questions

Patients with diabetes mellitus (DM) are at significantly greater risk for major cardiovascular events (MACE) than non-DM patients. Primary and secondary prevention of cardiovascular disease (CVD) involves a multifactorial approach that aims to treat the cluster of risk factors associated with this condition including blood disorders and clinical features, such as hyperglycaemia, dyslipidemia, hypercoagulation, obesity and hypertension. Platelet activation and aggregability play a key role in the genesis of arterial thrombus secondary to plaque rupture. For patients in secondary prevention, inhibition of platelet function is crucial to significantly decrease the rate of MACE. Inhibiting plaque rupture would therefore prevent platelet aggregation. For patients with DM presenting with an acute coronary syndrome (ACS), a dual antiplatelet therapy with antagonism of COX1 and P2Y12 is central to their treatment, especially in the setting of percutaneous coronary intervention (PCI) and stenting. Large randomized trials have demonstrated that platelet inhibition with the P2Y12 antagonist clopidogrel, is associated with a better short and long-term prognosis after an acute coronary syndrome. Despite the clinical benefits of clopidogrel in patients with ACS, it has limitations in urgent and early PCI due to its slow onset of action, large interindividual variability and drug-drug interactions resulting in inconsistent drug response with reduced efficacy, especially in patients with diabetes. Therefore, newer drugs with a rapid onset of action, and a more potent and predictable effect have been developed. Prasugrel and ticagrelor have demonstrated net clinical benefit over clopidogrel in two major randomized trials, including a large number of diabetic patients, in patients presenting with non-ST elevation ACS (NSTE-ACS) and ST-elevation ACS (STE-ACS) revascularized by PCI. The aim of this review is to provide an overview of aspirin, P2Y12 receptor antagonists, and Glycoprotein (GP) IIb-IIIa inhibitors in the management of diabetic patients, with a focus on perspectives in optimal and appropriate agent selection and timing of treatment in both primary and secondary prevention.

Sleep-related behavioral interaction between school-age siblings. Evaluation with CSHQ–PT

Young children are susceptible to sleep disturbances, particularly those related to behavior. Consequently they are more vulnerable to the negative impact of a disturbed sleep. There should exist a close monitoring to understand some factors that may act as disrupters on the balance of this vital function. Several studies have demonstrated that familial interaction can be a source of conflict in the context of the implementation and maintenance of adequate sleep habits, however there is only scarce data about the particular role of inter-individual interaction within the family members. The aim of this study was to evaluate how school-age siblings with different ages interact regarding important sleep-related neurobehavioral aspects. The portuguese validated version of the Children Sleep Habits Questionnaire (CSHQ-PT) was applied to 20 parents of siblings with a range of ages between 4 and 10 years old in a clinical context of a private pediatrics office. A total of 40 school-age healthy siblings were enrolled for this study. The mean age of the global sample was 7.52 ± 2.03 years old (9.10 ± 0.97 for the older siblings and 5.95 ± 1.53 for the younger siblings). CSHQ-PT global score was 47.35 ± 6.95 (46.55 ± 6.49 for the older group and 48.15 ± 7.46 for the younger group) without differences between groups and there was a moderate correlation between both groups regarding to this score ( r = .602; p = .005). Sleep schedules and sleep duration were similar in both groups. Regarding the subscales of CSHQ-PT, a moderate correlation between groups was found in night wakenings ( r = .648; p = .002) and sleep duration ( r = .481; p = .032). Furthermore there was no statistically significant differences regarding the CSHQ-PT subscales between older and younger brothers. Although in a relative small sample, these data suggest that similar inadequate sleep-related behaviors meaning behavioral sleep insomnia are shared by children of the same family. This points to the fact that education about sleep hygiene habits should be implemented continuously in pediatric clinical practice to avoid the maintenance of this deleterious sleep habits.

A New Data-Mining Method to Search for Behavioral Properties That Induce Alignment and Their Involvement in Social Learning in Medaka Fish (Oryzias Latipes)

BackgroundCoordinated movement in social animal groups via social learning facilitates foraging activity. Few studies have examined the behavioral cause-and-effect between group members that mediates this social learning.Methodology/Principal FindingsWe first established a behavioral paradigm for visual food learning using medaka fish and demonstrated that a single fish can learn to associate a visual cue with a food reward. Grouped medaka fish (6 fish) learn to respond to the visual cue more rapidly than a single fish, indicating that medaka fish undergo social learning. We then established a data-mining method based on Kullback-Leibler divergence (KLD) to search for candidate behaviors that induce alignment and found that high-speed movement of a focal fish tended to induce alignment of the other members locally and transiently under free-swimming conditions without presentation of a visual cue. The high-speed movement of the informed and trained fish during visual cue presentation appeared to facilitate the alignment of naïve fish in response to some visual cues, thereby mediating social learning. Compared with naïve fish, the informed fish had a higher tendency to induce alignment of other naïve fish under free-swimming conditions without visual cue presentation, suggesting the involvement of individual recognition in social learning.Conclusions/SignificanceBehavioral cause-and-effect studies of the high-speed movement between fish group members will contribute to our understanding of the dynamics of social behaviors. The data-mining method used in the present study is a powerful method to search for candidates factors associated with inter-individual interactions using a dataset for time-series coordinate data of individuals.

Information cascade ruling the fleeing behaviour of a gregarious insect

Collective fleeing is a complex process resulting from a network of environmental stimuli and interindividual interactions. Studies on fleeing behaviour have focused on the information spread initiated by a few stimulated individuals. Our goal was to link individuals' responses to the collective fleeing dynamics for gregarious insects simultaneously exposed to a stimulus. We found that an information cascade process occurs in groups of cockroaches, Periplaneta americana, simultaneously exposed to a light stimulus. Moreover, the global fleeing pattern depended on group size. The steps of the response (reacting to the stimulus, finding an opening and leaving the shelter) differed in their sensitivity to group size. First, immobile individuals inhibited the fleeing response, while moving individuals amplified it. Second, once individuals had reacted, they reached an opening and stopped. Their low probability per unit time of finding this opening was constant regardless of group size or the mobility level of group members. Finally, the individual probability of leaving the shelter increased with the number of moving individuals still inside. We integrated the different behavioural steps, analysed independently, into a stochastic model. The results based on this model are in agreement with our experimental observations. This model constitutes a template that enables the exploration of the influence of environmental and social factors at work in other species and situations.

Complex and dynamic population structures: synthesis, open questions, and future directions

The population structure of an evolutionary algorithm influences the dissemination and mixing of advantageous alleles, and therefore affects search performance. Much recent attention has focused on the analysis of complex population structures, characterized by heterogeneous connectivity distributions, non-trivial clustering properties, and degree---degree correlations. Here, we synthesize the results of these recent studies, discuss their limitations, and highlight several open questions regarding (1) unsolved theoretical issues and (2) the practical utility of complex population structures for evolutionary search. In addition, we will discuss an alternative complex population structure that is known to significantly influence dynamical processes, but has yet to be explored for evolutionary optimization. We then shift our attention toward dynamic population structures, which have received markedly less attention than their static counterparts. We will discuss the strengths and limitations of extant techniques and present open theoretical and experimental questions and directions for future research. In particular, we will focus on the prospects of active linking, wherein edges are dynamically rewired according to the genotypic or phenotypic properties of individuals, or according to the success of prior inter-individual interactions.