Conceptual and methodological issues in the comparative study of collective group movements

In our commentary, we highlight several conceptual and methodological problems that have hampered broader integration of studies of collective group movements. Specifically, we argue that studies of captive animals should only be used to elucidate behavioural mechanisms. Moreover, the diversity of physical environments in which group movements occur as well as the social diversity of groups deserve more consideration in integrative studies. Furthermore, tests of predictions based on modelling studies are often hampered by the fact that models include variables that are difficult or impossible to measure in real animals. We also advocate the use of an empirical, rather than subjective establishment of operational definitions of group movements and the associated individual roles. Finally, we emphasize the utility of controlled experiments in the study of collective decision-making and group movements and encourage their wider application.     

Patterns of group movements in juvenile domestic geese

We investigated collective movements in a flock of domestic geese (Anser domesticus) to test the consistency of group orders and the influence of individual traits and social relationships on movement patterns. The subjects were 20 juvenile females kept in an herbaceous enclosure. Two observers continuously videotaped their movements. Although the positions of individuals might change during moves, the geese tended to hold predictable positions in different movements. We found that geese more reactive to unexpected noises more often held front positions. Moreover, the higher the associativity of a bird as measured by number of neighbors at rest, the more frequent the bird acted as first mover. The analysis did not evidence any influence of dominance status on the positions of geese during progression. In contrast, geese linked by close bonds clustered during progression. The structuring influence of social bonds in collective movements might be a general feature of animals gifted with individual recognition abilities.     

Human dimensions of wolf (<Emphasis Type="Italic">Canis lupus</Emphasis>) conflicts in Finland

The growth of the Finnish wolf (Canis lupus) population during the last years has highlighted people’s contradictory attitudes toward wolves. The supranational conservation objectives brought on by Finland’s membership in the European Union (EU) and the regional application of the official policy on wolves have led to conflicts. This article is based on the preparation process of the wolf management plan in Finland. As a part of the process, a nationwide hearing was arranged in 2004. Fear of wolves is widespread and even more common in areas with low wolf population. People living in areas where wolves occur feel that they can no longer influence decision making which affects them and that the authorities, conservationists, and the EU do not listen to their opinions. Numerous requests have been made for the legislation and its interpretation, and concessions to these requests would promote consensus and increase tolerance for wolves. Proposed changes include reforming the damage compensation system and formulating a clearer interpretation of the conservation status of wolves. However, it seems impossible to create a policy that would be universally supported. As the wolf question has become more central in environmental policy, the conservation and management of the species have become more complicated, and the cooperation between various interest groups has declined. The wolf conflict could be mitigated by compromises, but because the conflict is value-based, solutions are illusive.     

The biological principles of swarm intelligence

The roots of swarm intelligence are deeply embedded in the biological study of self-organized behaviors in social insects. From the routing of traffic in telecommunication networks to the design of control algorithms for groups of autonomous robots, the collective behaviors of these animals have inspired many of the foundational works in this emerging research field. For the first issue of this journal dedicated to swarm intelligence, we review the main biological principles that underlie the organization of insects’ colonies. We begin with some reminders about the decentralized nature of such systems and we describe the underlying mechanisms of complex collective behaviors of social insects, from the concept of stigmergy to the theory of self-organization in biological systems. We emphasize in particular the role of interactions and the importance of bifurcations that appear in the collective output of the colony when some of the system’s parameters change. We then propose to categorize the collective behaviors displayed by insect colonies according to four functions that emerge at the level of the colony and that organize its global behavior. Finally, we address the role of modulations of individual behaviors by disturbances (either environmental or internal to the colony) in the overall flexibility of insect colonies. We conclude that future studies about self-organized biological behaviors should investigate such modulations to better understand how insect colonies adapt to uncertain worlds.     

Resource exploitation strategies in the presence of traffic between food sources

A mathematical model of food recruitment and resource exploitation in group-living organisms accounting for direct traffic of individuals between the available sources is developed. It is shown that traffic between sources gives rise to the enhancement of the range of stability of the homogeneous mode of exploitation and of the range of coexistence of homogeneous and semi-inhomogeneous ones, as well as the appearance of symmetry breaking transitions leading to fully inhomogeneous exploitation modes.     

基于贮食行为的鸟类社会认知研究进展

贮食是动物应对环境变化和不可预测性而进化出的有效生存对策,认知则是当前鸟类学研究的热点问题之一。目前鸟类贮食行为中的认知研究多集中在空间认知,而社会认知研究相对滞后。对于贮食物种而言,储藏食物被盗现象非常普遍,为了避免被盗食,贮食者不仅要有发达的空间认知能力去记忆贮食地点,同时还需要极强的社会认知能力处理与盗食者的关系,可见社会认知在鸟类的贮食行为中扮演着重要角色。本文将从鸟类贮食的社会关系认知以及社会地位认知两个方面,对鸟类贮食行为中的社会认知研究进行综述,以期为后续鸟类社会认知研究提供借鉴和参考。     

The development and evaluation of consensus chloroplast primer pairs that possess highly variable sequence regions in a diverse array of plant taxa

Although universal or consensus chloroplast primers are available, they are limited by their number and genomic distribution. Therefore, a set of consensus chloroplast primer pairs for simple sequence repeats (ccSSRs) analysis was constructed from tobacco (Nicotiana tabacum L.) chloroplast sequences. These were then tested for their general utility in the genetic analysis of a diverse array of plant taxa. In order to increase the number of ccSSRs beyond that previously reported, the target sequences for SSR motifs was set at A or T (n 7) mononucleotide repeats. Each SSR sequence motif, along with ±200-bp flanking sequences from the first of each mononucleotide base repeat, was screened for homologies with chloroplast DNA sequences of other plant species in GenBank databases using BLAST search procedures. Twenty three putative marker loci that possessed conserved flanking sequence spans were selected for consensus primer pair construction using commercially available computer algorithms. All primer pairs produced amplicons after PCR employing genomic DNA from members of the Cucurbitaceae (six species) and Solanaceae (four species). Sixteen, 22 and 19 of the initial 23 primer pairs were successively amplified by PCR using template DNA from species of the Apiaceae (two species), Brassicaceae (one species) and Fabaceae (two species), respectively. Twenty of 23 primer pairs were also functional in three monocot species of the Liliaceae [onion (Allium cepa L.) and garlic (Allium sativum L.)], and the Poaceae [oat (Avena sativa L.)]. Sequence analysis of selected ccSSR fragments suggests that ccSSR length and sequence variation could be useful as a tool for investigating the genetic relationships within a genus or closely related taxa (i.e., tribal level). In order to provide for a marker system having significant coverage of the cucumber chloroplast genome, ccSSR primers were strategically "recombined" and named recombined consensus chloroplast primers (RCCP) for PCR analysis. Successful amplification after extended-length PCR of 16 RCCP primer pairs from cucumber (Cucumis sativus L.) DNA suggested that the amplicons detected are representative of the cucumber chloroplast genome. These RCCP pairs, therefore, could be useful as an initial molecular tool for investigation of traits related to a chloroplast gene(s) in cucumber, and other closely related species.Communicated by C. Möllers     

Normalisation of gait EMGs: a re-examination

The purpose of this study was to compare four different methods of normalising electromyograms (EMGs) recorded during normal gait. Comparisons were made between the amplitude, intra-individual variability and inter-individual variability of EMGs. Surface EMGs were recorded from the biceps femoris, semitendinosus, vastus lateralis and vastus medialis of ten males and two females while they walked on a treadmill at a self-selected speed. EMGs from the same muscles were subsequently recorded during isometric maximal voluntary contractions (MVCs) and concentric, isokinetic MVCs that were performed between 0.52 and 7.85 rad·s⁻¹ on a BIODEX dynamometer. EMGs were also recorded during eccentric, isokinetic MVCs between 0.52 and 2.62 rad·s⁻¹. Gait EMGs were then normalised at 2% intervals of the gait cycle by expressing them as a percentage of the following reference values: the mean (mean dynamic method) and the peak (peak dynamic method) EMG from the intra-individual ensemble average; the EMG from an isometric MVC (isometric MVC method); and the EMG from an isokinetic MVC that occurred with the same muscle action, length and velocity of musculotendinous unit as the gait EMGs (isokinetic MVC method). The isokinetic MVC method produced significantly greater (P<0.05) intra-individual variability compared to the other methods when it was measured using the variance ratio. Inter-individual variability of gait EMGs, again measured using the variance ratio, was also greatest when they were normalised using the isokinetic MVC method. The pattern and amplitude of EMGs normalised using the isometric MVC method and the isokinetic MVC method were very similar (root mean square difference and absolute difference both less than 3%). It was concluded that the isokinetic MVC method should not be adopted by gait researchers or clinicians as it does not reduce intra- or inter-individual variability anymore than existing normalisation methods, nor does it provide a more representative measure of muscle activation during gait than the isometric MVC method.     

The social gradient in health: The effect of absolute income and subjective social status assessment on the individual's health in Europe

Using data on individuals aged between 50 and 65 from 6 European countries, this study investigates the effect of absolute income and subjective social status assessment on health in the light of medical evidence indicating that the individual's position in the social hierarchy undermines his/her mental and physical health. The paper shows that individuals’ own income has a positive, but modest effect on health. Importantly, subjective social status assessment has a significant effect on all health measurements. Finally, the results show that individuals from deprived families (when at the age of 14) have poorer physical and mental health.     

食物诱导长爪沙鼠集群贮食的野外实验设计及其在社群研究中的应用

长爪沙鼠为典型的群居性鼠类。在自然条件下该鼠的集群贮食活动随时可为人工投放的种子食物所导引。本文依据组群个体合作贮食的习性,并结合剪趾和染毛双重标记的重捕跟踪方法设计了着重观测社群结构、群内个体序位、领域边界及相关社群行为的野外实验。据2(X)2年5月对4个相邻洞群的观测结果分析表明,应用此法便于在复杂的社群环境中直接确认组群成员及其属性,亦便于分辨同一组群或不同组群成员之间发生的行为事件及相关过程,且能在重复实验中得以验证。为在野外条件下定量研究长爪沙鼠社群行为提供了一种便捷可靠的观测方法。     

Implicit associations with social status: the effects of relationship involvement

The study tested the proposition that relationship involvement influences the implicit responses of women to high- and low-status professions. It was hypothesized that when a high-involvement context was primed, women would have more positive implicit associations with high-status occupations than when a low-involvement context was primed. In contrast, when a high-involvement context was primed, women would have more negative associations with low-status occupations than when a low-involvement context was primed. To test the hypothesis, 123 female participants received a high or low relationship involvement prime. Then the participants completed a single category implicit associations test designed to measure the participants' associations with either high- or low-status occupations. As predicted, the relationship involvement prime influenced the positivity of associations made with high- and low-status occupations. The study pointed to the possibility that persons possess evolutionary-based implicit associations.     

Celebrities: From Teachers to Friends

In this paper we present two compatible hypotheses to explain interest in celebrity gossip. The Learning Hypothesis explains interest in celebrity gossip as a by-product of an evolved mechanism useful for acquiring fitness-relevant survival information. The Parasocial Hypothesis sees celebrity gossip as a diversion of this mechanism, which leads individuals to misperceive celebrities as people who are part of their social network. Using two preliminary studies, we tested our predictions. In a survey with 838 respondents and in-depth interviews with 103 individuals, we investigated how interest in celebrity gossip was related to several dimensions of the participants’ social lives. In support of the Learning Hypothesis, age proved to be a strong predictor of interest in celebrities. In partial support of the Parasocial Hypothesis, media exposure, but not social isolation, was a strong predictor of interest in celebrities. The preliminary results support both theories, indicate that across our life span celebrities move from being teachers to being friends, and open up a list of future research opportunities.

Disentangling cognitive processes from neural activation and psychic mechanisms: The example of empathy

Empathy processes can be explored within a three-level model distinguishing neuronal, cognitive and intra-psychic operating levels. Cognitive and intra-psychic processes need not to be collapsed. Neural systems involved in empathy are described through neuroimaging and event-related potential (ERP) studies. On the cognitive level, empathy is threefold: procedural, semantic and biographical. Automatically activated since birth, procedural empathy processes are deeply enrooted in visuo-motor response capacities and responsible for automatic mimicry. These processes might rely on a prior sensori-motor contagion system. Semantic empathy parallels language development and expresses connexion between words, meaning and emotion. Biographical emerges later in life and corresponds to the interweaving of personal experience with feelings and words, together with a capacity to bridge with the others’ experiences. On the intra-psychic level, defence mechanisms as well as identification processes, depicted from a subjective and interpersonal standpoint, are corresponding, without being similar, to empathetic processes described in cognitive neuroscience studies. Studies on semantic empathy need to control for the participants biographical information and concomitant memory activation. The interface between cognitive and intra-psychic processes needs to be further investigated.     

Tension-dependent collective cell movements in the early gastrula ectoderm of Xenopus laevis embryos

Ventral ectodermal explants taken from early gastrula embryos of Xenopus laevis were artificially stretched either by two opposite concentrated forces or by a distributed force applied to the internal explant’s layer. These modes of stretching reflect different mechanical situations taking place in the normal development. Two main types of kinematic response to the applied tensions were detected. First, by 15 min after the onset of concentrated stretching a substantial proportion of the explant’s cells exhibited a concerted movement towards the closest point of the applied stretching force. We define this movement as tensotaxis. Later, under both concentrated and distributed stretching, most of the cell’s trajectories became reoriented perpendicular to the stretching force, and the cells started to intercalate between each other, both horizontally and vertically. This was accompanied by extensive elongation of the outer ectodermal cells and reconstruction of cell-cell contacts. The intercalation movements led first to a considerable reduction in the stretch-induced tensions and then to the formation of peculiar bipolar ”embryoid” shapes. The type and intensity of the morphomechanical responses did not depend upon the orientation of a stretching force in relation to the embryonic axes. We discuss the interactions of the passive and active components in tension-dependent cell movements and their relations to normal morphogenetic events. Received: 26 April 1999 / Accepted: 30 August 1999     

Peccary movements as determinants of the movements of large cats in Brazilian Amazonia

As part of a study on the ecology of a community of middle-sized and larger mammals in a seasonally dry forest in the far north of the Brazilian Amazonia, peccaries (the white-lipped peccary Tayassu pecari and the collared peccary Tayassu tajacu ) and large cats (the jaguar Panthera onca and the puma Puma concolor ) were regularly surveyed for 1 year. Diurnal and nocturnal surveys were carried out by the line-transect method, in five different forest types along a 10 km transect, and data were collected on their use of the forest types. The peccary herds and the large cats were sighted regularly throughout the study period, but more frequently over the dry season in the high-ground forests in eastern Maracá. Over the dry season, when food was scarce except in the Buritizals, T. pecari , closely followed by a P. onca , monopolized the Buritizal forests, whereas T. tajacu , followed by a P. concolor , exploited the other available high-ground forest types. Fluctuations in food supply regulated the dynamics of the two species of peccaries, which ultimately determined the whereabouts of the large cat predators. This may be a counter-strategy to survive in an extremely seasonal environment where food, more than any other variable, is the key determinant of the survival of both peccaries and large cats.     

Maternal care and foal social relationships in a herd of Sorraia horses: Influence of maternal rank and experience

The influence of maternal rank and experience on patterns of maternal care and social relationships of foals were investigated in a managed herd of Sorraia horses, Equus caballus. Social interactions and spatial relationships of 13 foals (seven females and six males) born to seven mares were examined from birth to 10 months of life, within the three major periods of foal development. Conflict over suckling between dam and foal was not generally affected by rank and experience, but higher-ranking mothers allowed more suckling during late lactation than lower-ranking mothers. Foals of higher-ranking mares spent more time in proximity to the mother during socialization. Maternal rank and experience did not significantly affect maternal protectiveness, foal independence from the mother or the development of affiliative relationships between foals and group members. Foals of higher-ranking mares received lower frequencies of aggression from other horses only in the first month of life. Dominance relationships among foals depended mainly on aggressiveness and were not associated with maternal rank. The large variability in maternal behaviour, the absence of a significant association between maternal rank and body condition at parturition and the stable social environment within this herd may partly account for the reported results.