On the possibility of identifying human subjects using behavioural complexity analyses

Background: Identification of human subjects using a geometric approach to complexity analysis of behavioural data is designed to provide a basis for a more precise diagnosis leading towards personalised medicine. Methods: The approach is based on capturing behavioural time-series that can be characterized by a fractional dimension using non-invasive longer-time acquisitions of heart rate, perfusion, blood oxygenation, skin temperature, relative movement and steps frequency. The geometry based approach consists in the analysis of the area and centroid of convex hulls encapsulating the behavioural data represented in Euclidian index spaces based on the scaling properties of the self-similar normally distributed behavioural time-series of the above mentioned quantities. Results: An example demonstrating the presented approach of behavioural fingerprinting is provided using sensory data of eight healthy human subjects based on approximately fifteen hours of data acquisition. Our results show that healthy subjects can be factorized to different similarity groups based on a particular choice of a convex hull in the corresponding Euclidian space. One of the results indicates that healthy subjects share only a small part of the convex hull pertaining to a highly trained individual from the geometric comparison point of view. Similarly, the presented pair-wise individual geometric similarity measure indicates large differences among the subjects suggesting the possibility of neuro-fingerprinting. Conclusions: Recently introduced multi-channel body-attached sensors provide a possibility to acquire behavioural time-series that can be mathematically analysed to obtain various objective measures of behavioural patterns yielding behavioural diagnoses favouring personalised treatments of, e.g., neuropathologies or aging.     

A new approach for the assessment of stochastic variation: analysis of behavioural response in blue mussel (Mytilus edulis L.)

One of the most effective techniques for evaluating stress is the analysis of developmental stability, measured by stochastic variation based particularly on fluctuating asymmetry, i.e. a variance in random deviations from perfect bilateral symmetry. However, the application of morphological methods is only possible when an organism lives under testing conditions during a significant part of its ontogenesis. Contrary to morphological characters, behavior can change very fast. Consequently, methods based on behavioural characters may have advantages over more traditional approaches. In this study we describe the technique of assessing stochastic variation, using not morphological, but behavioural characters. To measure stochastic variation of behavioural response, we assessed the stability of the isolation reaction of blue musselMytilus edulis at regular changes of salinity. With increasing temperature from +12°C to +20°C stochastic variation of the isolation reaction increased, which is a common response to change of environmental conditions. In this way, we have developed a method of assessing stochastic variation of behavioural response in molluscs. This method may find a great range of applications, because its usage does not require keeping animals in tested conditions for a long time.     

Behavioural specialization in pre-reproductive colonies of the allodapine beeExoneura bicolor (Hymenoptera: Anthophoridae)

Summary Exoneura bicolor is a univoltine allodapine bee common in montane forests of southern Australia, where it exhibits a semisocial/quasisocial colony organization. Within-nest behaviour in postemergence autumn nests ofExoneura bicolor was recorded with the aim of studying behavioural specialization in pre-reproductive colonies. Ten complete colonies were transferred to purpose-built observation nests shortly before brood eclosion in late summer. Behaviour within observation nests was recorded for periods of up to 44 days after establishment, covering a period when colonies are preparing for overwintering. Dispersal of females and brood rearing do not occur at this time, although some females may become inseminated. Analyses of data using multivariate techniques indicated four distinguishable behavioural castes, designated here as Guards, Nest Absenters, Nest Modifiers and Non-recruits. This represents a higher degree of behavioural specialization than recorded to date for other allodapines. Behaviours performed by Guards and Nest Absenters are likely to involve considerable risks, but benefit the colony as a whole, so that some nestmates in prereproductive colonies exhibit altruism that frequently aids adult siblings or cousins. The males in our study were fed by females via trophallaxis and two of the males participated in nest maintenance tasks. Our results suggest that autumn colonies ofE. bicolor form well-integrated behavioural units even though brood rearing does not commence until the following spring.     

Hunting strategy of a generalist ant species proposed as a biological control agent against termites

We studied the hunting behaviour of Myrmicaria opaciventris (Hymenoptera: Formicidae) in order to evaluate if it can be used as a biological control agent against the termites that damage sugarcane plantations. Hunting workers foraged in groups and recruited nestmates at short-range when they encountered large termite soldiers or groups of small termite workers. Differences in prey capture concerned the: (1) means of detection (from a distance or by contact); (2) termite body part seized (small termites seized by the body; large termites by an appendage); (3) percentages of prey abandoned; and (4) use of venom. The sting of the workers is spatulated implying a topical application of the venom on the prey. Large termites were stretched by several workers whose adherence to the substrate is facilitated by well-developed arolia and claws on the legs while others spread venom on the body and carved it up. An adaptation to termite capture was noted with a distribution of tasks between the workers which subdued prey, and those which transported it. In the former case, the workers easily eliminated termite soldiers, successively attacked several termite workers and even captured new individuals while holding the first ones captured between their mandibles before retrieving them all at once. The remaining individuals were retrieved by the transporting workers. Given this particularly effective predatory strategy, we concluded that, under certain conditions, M. opaciventris can be used as a biological control agent against termites.     

Transitions: Homo erectus and the Acheulian: the Ethiopian sites of Gadeb and the Middle Awash

Significant differences in activity-site patterning and artifact composition at Middle Pleistocene localities in Ethiopia's high plains and Afar Rift are indications of both single-episode, small-site residues from small groups and multi-purpose, multiple occupation sites from which larger, temporary groupings might be inferred. Reconstructions of palaeo-environments and geography show that large assemblages relate to relatively stable topography, such as stream channels or lake margins, while small assemblages are more common in deltaic situations of rapid sedimentation and burial in the Rift that preclude possibility of reoccupation. A model for Acheulian socio-economic behaviour within the drier African savanna, based (in part) on chimpanzee behaviour in open savanna habitats, is proposed. This takes the form of organization into relatively extensive territories, each with several more closed-vegetation core areas, of limited extent close to permanent water, surrounded by more extensive areas of drier, open savanna, regularly exploited and patrolled by small groups. Movement from one core area to another was rapid and made together as a group, to minimize danger from large predators and competition from other hominid groups.     

Behavioural syndromes and social insects: personality at multiple levels

Animal personalities or behavioural syndromes are consistent and/or correlated behaviours across two or more situations within a population. Social insect biologists have measured consistent individual variation in behaviour within and across colonies for decades. The goal of this review is to illustrate the ways in which both the study of social insects and of behavioural syndromes has overlapped, and to highlight ways in which both fields can move forward through the synergy of knowledge from each. Here we, (i) review work to date on behavioural syndromes (though not always referred to as such) in social insects, and discuss mechanisms and fitness effects of maintaining individual behavioural variation within and between colonies; (ii) summarise approaches and principles from studies of behavioural syndromes, such as trade‐offs, feedback, and statistical methods developed specifically to study behavioural consistencies and correlations, and discuss how they might be applied specifically to the study of social insects; (iii) discuss how the study of social insects can enhance our understanding of behavioural syndromes—research in behavioural syndromes is beginning to explore the role of sociality in maintaining or developing behavioural types, and work on social insects can provide new insights in this area; and (iv) suggest future directions for study, with an emphasis on examining behavioural types at multiple levels of organisation (genes, individuals, colonies, or groups of individuals).     

Personality-dependent dispersal in the invasive mosquitofish: group composition matters

Understanding/predicting ecological invasions is an important challenge in modern ecology because of their immense economical and ecological costs. Recent studies have revealed that within-species variation in behaviour (i.e. animal personality) can shed light on the invasion process. The general hypothesis is that individuals' personality type may affect their colonization success, suggesting that some individuals might be better invaders than others. We have recently shown that, in the invasive mosquitofish (Gambusia affinis), social personality trait was an important indicator of dispersal distance, with more asocial individuals dispersing further. Here, we tested how mean personality within a population, in addition to individual personality type, affect dispersal and settlement decisions in the mosquitofish. We found that individual dispersal tendencies were influenced by the population's mean boldness and sociability score. For example, individuals from populations with more asocial individuals or with more bold individuals are more likely to disperse regardless of their own personality type. We suggest that identifying behavioural traits facilitating invasions, even at the group level, can thus have direct applications in pest management.     

Behavioural Flexibility and Numerous Potential Sources of Introduction for the Sacred Ibis: Causes of Concern in Western Europe?

In order to examine the dynamics and potential impact of the recently introduced sacred ibis Threskiornis aethiopicus, we review the published and unpublished data and report new information on its distribution in West European countries and particularly in France. This species, which escaped from zoos during the 1990s, is well established and has spread on the Atlantic coast and in Mediterranean region of France, with a mid-winter population reaching ca. 3200 individuals in winter 2004–2005 and ca. 1100 breeding pairs in spring 2005. The species has also escaped from zoological parks in Belgium, Germany, Spain, Italy and Portugal, and feral populations are established in Piedmont (Italy) and in the Canary Islands (Spain). The species dispersing ability has led to observations over hundreds of kilometres from the established colonies. We identify that in temperate habitats the sacred ibis shows a behavioural flexibility similar to that known in its tropical native range, including a large diet spectrum (insects, molluscs, refuse, bird eggs, etc.) and an ability to use various habitats (meadows, rubbish dumps, marshes, reedbeds, seashore, ploughed fields, etc.). This plasticity, the fact that predation by ibises is observed on nests of threatened bird species, and the number of potential sources of ibis in Europe (zoos) are causes of concern suggesting that precautionary measures should be taken to prevent the spread of this new alien species.     

Aggressive females become aggressive males in a sex-changing reef fish

Many animal populations display consistent individual differences in suites of correlated behaviours. While these so called 'animal personalities' can substantially influence the ecology and evolution of populations, little is known about cross-sex correlations of behaviour and thus the potential of personality to limit sex-specific behavioural adaptations. Here, we experimentally induced sex-change in the sequentially hermaphroditic reef fish Parapercis cylindrica and demonstrate the existence of tight cross-sex correlations for two behaviours with presumed different sex-specific optima. Individuals that were relatively more active and aggressive females were found to become relatively more active and aggressive males. By identifying personality as a potential genetic constraint on the resolution of intralocus sexual conflict over behaviour, our findings have important ecological and evolutionary implications for a wide range of species.     

Psychoactive pollution suppresses individual differences in fish behaviour

Environmental contamination by pharmaceuticals is global, substantially altering crucial behaviours in animals and impacting on their reproduction and survival. A key question is whether the consequences of these pollutants extend beyond mean behavioural changes, restraining differences in behaviour between individuals. In a controlled, two-year, multigenerational experiment with independent mesocosm populations, we exposed guppies (Poecilia reticulata) to environmentally realistic levels of the ubiquitous pollutant fluoxetine (Prozac). Fish (unexposed: n = 59, low fluoxetine: n = 57, high fluoxetine: n = 58) were repeatedly assayed on four separate occasions for activity and risk-taking behaviour. Fluoxetine homogenized individuals'' activity, with individual variation in populations exposed to even low concentrations falling to less than half that in unexposed populations. To understand the proximate mechanism underlying these changes, we tested the relative contribution of variation within and between individuals to the overall decline in individual variation. We found strong evidence that fluoxetine erodes variation in activity between but not within individuals, revealing the hidden consequences of a ubiquitous contaminant on phenotypic variation in fish—likely to impair adaptive potential to environmental change.