Odile Petit
Research interests
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InterestsBehavioral Ecology, Ethology, Animal Cognition, Animal Communication, Behavioural biology, Animal Behavior
Publications
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4.41Impact points
From Social Network (Centralized vs. Decentralized) to Collective Decision-Making (Unshared vs. Shared Consensus).
PloS one. 01/2012; 7(2):e32566.
Relationships we have with our friends, family, or colleagues influence our personal decisions, as well as decisions we make together with others. As in human beings, despotism and egalitarian societies seem to also exist in animals. While studies have shown that social networks constrain many pheno... [more] Relationships we have with our friends, family, or colleagues influence our personal decisions, as well as decisions we make together with others. As in human beings, despotism and egalitarian societies seem to also exist in animals. While studies have shown that social networks constrain many phenomena from amoebae to primates, we still do not know how consensus emerges from the properties of social networks in many biological systems. We created artificial social networks that represent the continuum from centralized to decentralized organization and used an agent-based model to make predictions about the patterns of consensus and collective movements we observed according to the social network. These theoretical results showed that different social networks and especially contrasted ones - star network vs. equal network - led to totally different patterns. Our model showed that, by moving from a centralized network to a decentralized one, the central individual seemed to lose its leadership in the collective movement's decisions. We, therefore, showed a link between the type of social network and the resulting consensus. By comparing our theoretical data with data on five groups of primates, we confirmed that this relationship between social network and consensus also appears to exist in animal societies.
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1.57Impact points
Social network modeling: a powerful tool for the study of group scale phenomena in primates.
American journal of primatology. 08/2011; 73(8):741-7.
Social Network Analysis is now a valuable tool to study social complexity in many animal species, including primates. However, this framework has rarely been used to implement quantitative data on the social structure of a group within computer models. Such approaches allow the investigation of how ... [more] Social Network Analysis is now a valuable tool to study social complexity in many animal species, including primates. However, this framework has rarely been used to implement quantitative data on the social structure of a group within computer models. Such approaches allow the investigation of how social organization constrains other traits and also how these traits can impact the social organization in return. In this commentary, we discuss the powerful potential of social network modeling as a way to study group scale phenomena in primates. We describe the advantages of using such a method and we focus on the specificity of this approach in primates, given the particularities of their social networks compared with those of other taxa. We also give practical considerations and a list of examples as for the choice of parameters that can be used to implement the social layer within the models.
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2.57Impact points
Group size, grooming and fission in primates: a modeling approach based on group structure.
Journal of theoretical biology. 03/2011; 273(1):156-66.
In social animals, fission is a common mode of group proliferation and dispersion and may be affected by genetic or other social factors. Sociality implies preserving relationships between group members. An increase in group size and/or in competition for food within the group can result in decrease... [more] In social animals, fission is a common mode of group proliferation and dispersion and may be affected by genetic or other social factors. Sociality implies preserving relationships between group members. An increase in group size and/or in competition for food within the group can result in decrease certain social interactions between members, and the group may split irreversibly as a consequence. One individual may try to maintain bonds with a maximum of group members in order to keep group cohesion, i.e. proximity and stable relationships. However, this strategy needs time and time is often limited. In addition, previous studies have shown that whatever the group size, an individual interacts only with certain grooming partners. There, we develop a computational model to assess how dynamics of group cohesion are related to group size and to the structure of grooming relationships. Groups' sizes after simulated fission are compared to observed sizes of 40 groups of primates. Results showed that the relationship between grooming time and group size is dependent on how each individual attributes grooming time to its social partners, i.e. grooming a few number of preferred partners or grooming equally or not all partners. The number of partners seemed to be more important for the group cohesion than the grooming time itself. This structural constraint has important consequences on group sociality, as it gives the possibility of competition for grooming partners, attraction for high-ranking individuals as found in primates' groups. It could, however, also have implications when considering the cognitive capacities of primates.
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Land use in semi-free ranging Tonkean macaques Macaca tonkeana depends on environmental conditions: A geo-graphical information system approach
Current Zoology. 01/2011;
Wild animals use their habitat according to ecological pressures such as predation, resource availability or temperature, yet little is known about how individuals use their environment in semi free-ranging conditions. We assessed whether a semi-free ranging group of Tonkean macaques Macaca tonkeana... [more] Wild animals use their habitat according to ecological pressures such as predation, resource availability or temperature, yet little is known about how individuals use their environment in semi free-ranging conditions. We assessed whether a semi-free ranging group of Tonkean macaques Macaca tonkeana used its wooded parkland in a heterogeneous way. GIS and GPS were used to determine whether individuals adjusted their behaviors according to variation in environmental constraints over time of day and the course of a year. We demonstrated that social and resting activities occurred in high altitude areas and areas with a high density of bushes, whereas the group foraged in areas where the density of bushes and grass was low. In general, the animals used areas exposed to the sun that were not on a slope. Semi-free ranging Tonkean macaques seemed to behave like their wild counterparts in terms of activity budget, land use per activity and thermoregulation [Current Zoology 57 (1): 8–17, 2011].
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4.41Impact points
Evidence of the trade-off between starvation and predation risks in ducks.
PloS one. 01/2011; 6(7):e22352.
The theory of trade-off between starvation and predation risks predicts a decrease in body mass in order to improve flight performance when facing high predation risk. To date, this trade-off has mainly been validated in passerines, birds that store limited body reserves for short-term use. In the l... [more] The theory of trade-off between starvation and predation risks predicts a decrease in body mass in order to improve flight performance when facing high predation risk. To date, this trade-off has mainly been validated in passerines, birds that store limited body reserves for short-term use. In the largest avian species in which the trade-off has been investigated (the mallard, Anas platyrhynchos), the slope of the relationship between mass and flight performance was steeper in proportion to lean body mass than in passerines. In order to verify whether the same case can be applied to other birds with large body reserves, we analyzed the response to this trade-off in two other duck species, the common teal (Anas crecca) and the tufted duck (Aythya fuligula). Predation risk was simulated by disturbing birds. Ducks within disturbed groups were compared to non-disturbed control birds. In disturbed groups, both species showed a much greater decrease in food intake and body mass during the period of simulated high risk than those observed in the control group. This loss of body mass allows reaching a more favourable wing loading and increases power for flight, hence enhancing flight performances and reducing predation risk. Moreover, body mass loss and power margin gain in both species were higher than in passerines, as observed in mallards. Our results suggest that the starvation-predation risk trade-off is one of the major life history traits underlying body mass adjustments, and these findings can be generalized to all birds facing predation. Additionally, the response magnitude seems to be influenced by the strategy of body reserve management.
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4.41Impact points
Behavioural adjustment in response to increased predation risk: a study in three duck species.
PloS one. 01/2011; 6(4):e18977.
Predation directly triggers behavioural decisions designed to increase immediate survival. However, these behavioural modifications can have long term costs. There is therefore a trade-off between antipredator behaviours and other activities. This trade-off is generally considered between vigilance ... [more] Predation directly triggers behavioural decisions designed to increase immediate survival. However, these behavioural modifications can have long term costs. There is therefore a trade-off between antipredator behaviours and other activities. This trade-off is generally considered between vigilance and only one other behaviour, thus neglecting potential compensations. In this study, we considered the effect of an increase in predation risk on the diurnal time-budget of three captive duck species during the wintering period. We artificially increased predation risk by disturbing two groups of 14 mallard and teals at different frequencies, and one group of 14 tufted ducks with a radio-controlled stressor. We recorded foraging, vigilance, preening and sleeping durations the week before, during and after disturbance sessions. Disturbed groups were compared to an undisturbed control group. We showed that in all three species, the increase in predation risk resulted in a decrease in foraging and preening and led to an increase in sleeping. It is worth noting that contrary to common observations, vigilance did not increase. However, ducks are known to be vigilant while sleeping. This complex behavioural adjustment therefore seems to be optimal as it may allow ducks to reduce their predation risk. Our results highlight the fact that it is necessary to encompass the whole individual time-budget when studying behavioural modifications under predation risk. Finally, we propose that studies of behavioural time-budget changes under predation risk should be included in the more general framework of the starvation-predation risk trade-off.
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4.41Impact points
Individual analyses of Lévy walk in semi-free ranging Tonkean macaques (Macaca tonkeana).
PloS one. 01/2011; 6(10):e26788.
Animals adapt their movement patterns to their environment in order to maximize their efficiency when searching for food. The Lévy walk and the Brownian walk are two types of random movement found in different species. Studies have shown that these random movements can switch from a Brownian to a Lé... [more] Animals adapt their movement patterns to their environment in order to maximize their efficiency when searching for food. The Lévy walk and the Brownian walk are two types of random movement found in different species. Studies have shown that these random movements can switch from a Brownian to a Lévy walk according to the size distribution of food patches. However no study to date has analysed how characteristics such as sex, age, dominance or body mass affect the movement patterns of an individual. In this study we used the maximum likelihood method to examine the nature of the distribution of step lengths and waiting times and assessed how these distributions are influenced by the age and the sex of group members in a semi free-ranging group of ten Tonkean macaques. Individuals highly differed in their activity budget and in their movement patterns. We found an effect of age and sex of individuals on the power distribution of their step lengths and of their waiting times. The males and old individuals displayed a higher proportion of longer trajectories than females and young ones. As regards waiting times, females and old individuals displayed higher rates of long stationary periods than males and young individuals. These movement patterns resembling random walks can probably be explained by the animals moving from one location to other known locations. The power distribution of step lengths might be due to a power distribution of food patches in the enclosure while the power distribution of waiting times might be due to the power distribution of the patch sizes.
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4.41Impact points
Behavioural Adjustment in Response to Increased Predation Risk: A Study in Three Duck Species
PLoS ONE. 01/2011; 6:e 18977.
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4.41Impact points
Evidence of the Trade-Off between Starvation and Predation Risks in Ducks
PLoS ONE. 01/2011; 6:e22352.
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1.57Impact points
How can social network analysis improve the study of primate behavior?
American journal of primatology. 12/2010; 73(8):703-19.
When living in a group, individuals have to make trade-offs, and compromise, in order to balance the advantages and disadvantages of group life. Strategies that enable individuals to achieve this typically affect inter-individual interactions resulting in nonrandom associations. Studying the pattern... [more] When living in a group, individuals have to make trade-offs, and compromise, in order to balance the advantages and disadvantages of group life. Strategies that enable individuals to achieve this typically affect inter-individual interactions resulting in nonrandom associations. Studying the patterns of this assortativity using social network analyses can allow us to explore how individual behavior influences what happens at the group, or population level. Understanding the consequences of these interactions at multiple scales may allow us to better understand the fitness implications for individuals. Social network analyses offer the tools to achieve this. This special issue aims to highlight the benefits of social network analysis for the study of primate behaviour, assessing it's suitability for analyzing individual social characteristics as well as group/population patterns. In this introduction to the special issue, we first introduce social network theory, then demonstrate with examples how social networks can influence individual and collective behaviors, and finally conclude with some outstanding questions for future primatological research.
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4.11Impact points
From the first intention movement to the last joiner: macaques combine mimetic rules to optimize their collective decisions.
Proceedings. Biological sciences / The Royal Society. 11/2010; 278(1712):1697-704.
Mechanisms related to collective decision making have recently been found in almost all animal reigns from amoebae to worms, insects and vertebrates, including human beings. Decision-making mechanisms related to collective movements-including pre-departure and joining-have already been studied at di... [more] Mechanisms related to collective decision making have recently been found in almost all animal reigns from amoebae to worms, insects and vertebrates, including human beings. Decision-making mechanisms related to collective movements-including pre-departure and joining-have already been studied at different steps of the movement process, but these studies were always carried out separately. We therefore have no understanding of how these different processes are related when they underlie the same collective decision-making event. Here, we consider the whole departure process of two groups of Tonkean macaques (Macaca tonkeana), using a stochastic model. When several exclusive choices are proposed, macaques vote and choose the majority. Individuals then join the movement according to a mimetism based on affiliative relationships. The pre-departure quorum and the joining mimetic mechanism are probably linked, but we have not yet identified which transition mechanism is used. This study shows that decision-making related to macaque group movements is governed by a quorum rule combined with a selective mimetism at departure. This is the first time that transition mechanisms have been described in mammals, which consequently helps understand how a voting process leads to social amplification. Our study also provides the first complete proof that there is continuity in the decision-making processes underlying collective movements in mammals from the first intention movement right through to the last joiner.
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1.53Impact points
Decision-making processes: the case of collective movements.
Behavioural processes. 05/2010; 84(3):635-47.
Besides focusing on the adaptive significance of collective movements, it is crucial to study the mechanisms and dynamics of decision-making processes at the individual level underlying the higher-scale collective movements. It is now commonly admitted that collective decisions emerge from interacti... [more] Besides focusing on the adaptive significance of collective movements, it is crucial to study the mechanisms and dynamics of decision-making processes at the individual level underlying the higher-scale collective movements. It is now commonly admitted that collective decisions emerge from interactions between individuals, but how individual decisions are taken, i.e. how far they are modulated by the behaviour of other group members, is an under-investigated question. Classically, collective movements are viewed as the outcome of one individual's initiation (the leader) for departure, by which all or some of the other group members abide. Individuals assuming leadership have often been considered to hold a specific social status. This hierarchical or centralized control model has been challenged by recent theoretical and experimental findings, suggesting that leadership can be more distributed. Moreover, self-organized processes can account for collective movements in many different species, even in those that are characterized by high cognitive complexity. In this review, we point out that decision-making for moving collectively can be reached by a combination of different rules, i.e. individualized (based on inter-individual differences in physiology, energetic state, social status, etc.) and self-organized (based on simple response) ones for any species, context and group size.
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2.72Impact points
Short-term group fission processes in macaques: a social networking approach.
The Journal of experimental biology. 04/2010; 213(Pt 8):1338-46.
Living in groups necessarily involves a certain amount of within-group competition for food. Group members may have different motivations, implying the reaching of a consensus to stay cohesive. In some cases individuals fail to reach a common decision and the group splits; this can be temporary, as ... [more] Living in groups necessarily involves a certain amount of within-group competition for food. Group members may have different motivations, implying the reaching of a consensus to stay cohesive. In some cases individuals fail to reach a common decision and the group splits; this can be temporary, as seen in fission-fusion dynamics, or even irreversible. Most studies on fission-fusion dynamics published to date have focused on the influence of environmental constraints on sub-grouping patterns, but little is known about how social relationships affect individual choices for sub-groups. In this study, we used an agent-based model to understand the mechanisms underlying group fission in two semi-free-ranging groups of macaques: one group of Tonkean macaques (Macaca tonkeana) and one of rhesus macaques (M. mulatta). The results showed that sub-grouping patterns were mainly influenced by affiliative relationships. Moreover, the species-specific social style appeared to affect the probability of choosing a particular sub-group. In the tolerant Tonkean macaques, mechanisms underlying sub-grouping patterns resembled anonymous mimetism, while in the nepotistic rhesus macaques, kinship influenced the mechanisms underlying group fissions. As previous studies have shown, fission-fusion society may be a way to avoid social conflicts induced either by food or by social competition.
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5.76Impact points
Differences in nutrient requirements imply a non-linear emergence of leaders in animal groups.
PLoS computational biology. 01/2010; 6(9):e1000917.
Collective decision making and especially leadership in groups are among the most studied topics in natural, social, and political sciences. Previous studies have shown that some individuals are more likely to be leaders because of their social power or the pertinent information they possess. One ch... [more] Collective decision making and especially leadership in groups are among the most studied topics in natural, social, and political sciences. Previous studies have shown that some individuals are more likely to be leaders because of their social power or the pertinent information they possess. One challenge for all group members, however, is to satisfy their needs. In many situations, we do not yet know how individuals within groups distribute leadership decisions between themselves in order to satisfy time-varying individual requirements. To gain insight into this problem, we build a dynamic model where group members have to satisfy different needs but are not aware of each other's needs. Data about needs of animals come from real data observed in macaques. Several studies showed that a collective movement may be initiated by a single individual. This individual may be the dominant one, the oldest one, but also the one having the highest physiological needs. In our model, the individual with the lowest reserve initiates movements and decides for all its conspecifics. This simple rule leads to a viable decision-making system where all individuals may lead the group at one moment and thus suit their requirements. However, a single individual becomes the leader in 38% to 95% of cases and the leadership is unequally (according to an exponential law) distributed according to the heterogeneity of needs in the group. The results showed that this non-linearity emerges when one group member reaches physiological requirements, mainly the nutrient ones - protein, energy and water depending on weight - superior to those of its conspecifics. This amplification may explain why some leaders could appear in animal groups without any despotism, complex signalling, or developed cognitive ability.
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2.18Impact points
Body mass variations in disturbed mallards Anas platyrhynchos fit to the mass-dependent starvation-predation risk trade-off
Journal of Avian Biology. 01/2010; 41:637-644.
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From the first intention movement to the last joiner: macaques combine mimetic rules to optimize their collective decisions
Proceedings of the Royal Society B: Biological Sciences. 01/2010;
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Brood Desertion in Ducks: The Ecological Significance of Parental Care for Offspring Survival
Wildlife Biology in Practice. 01/2010;
The debate concerning the relative importance of the costs and benefits of parental investment decisions has created considerable controversy. This is especially true in the discussion for duck species, where the link between ending of parental care and offspring survival has not been fully determin... [more] The debate concerning the relative importance of the costs and benefits of parental investment decisions has created considerable controversy. This is especially true in the discussion for duck species, where the link between ending of parental care and offspring survival has not been fully determined. This experimental study tests whether mallard ducklings (Anas platyrhynchos; a non-crèching species with maternal care-) achieve maximum survival potential before the typical ending of the hen-brood bond. As mortality rates are at their highest during the first two weeks post-hatching, our experimental investigation of survival was restricted to ducklings from 2 weeks of age until fledging, in non-deserted (ND, control group; n=36) and prematurely abandoned (D, deserted treatment group; n=35) broods under free-ranging conditions. The experiment was conducted over two years to take differences in weather conditions into account. According to age periods, survival rates ranged from 65 to 95% in the D group and from 97 to 100% in the ND. Survival probability of deserted ducklings was 23% lower than that of the control group (p < 0.001) in 15 to 30 day old ducklings but was similar (p > 0.09) thereafter. Assuming that the hen-brood bond is time-disrupted at ~6 weeks post-hatching, our results are consistent with the idea that trade-offs associated with the provision and the consequent ceasing of maternal care have evolved according to the intrinsic ability of ducklings to survive on their own at ~4 weeks post-hatching. The dissipation of the behavioural-hormonal processes underlying the hen-brood bond probably requires a delay between these two events. The maintaining of maternal care for ~4 weeks post-hatching also coincides with the most critical periods of duckling vulnerability after hatching, during which the hen has an important anti-predator role to play.
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Selective mimetism at departure in collective movements of Macaca tonkeana: a theoretical and experimental approach
Animal Behaviour. 10/2009; 79:1087-1095.
In primates, authors have reported the specific organization of individuals during collective movements. Some authors have suggested that intentional mechanisms underlie this particular organization because primates have high cognitive abilities that can allow them to use this kind of behaviour. How... [more] In primates, authors have reported the specific organization of individuals during collective movements. Some authors have suggested that intentional mechanisms underlie this particular organization because primates have high cognitive abilities that can allow them to use this kind of behaviour. However, mechanisms underlying the emergence of complex systems are not necessarily complex and can be based on local rules. We investigated the joining processes observed during collective movements in one semi free-ranging group of Tonkean macaques, using an individualized agent-based model. The complex patterns observed, such as departure latencies, associations and order of individuals at departure of a collective movement, could be explained using a rule based on affiliative relationships. The decision an individual took to join the movement depended on the departure of its strongly affiliated individuals. Thus even in primates, complex collective behaviour may emerge from interactions between individuals following local behavioural rules.
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3.33Impact points
Signals use by leaders in Macaca tonkeana and Macaca mulatta: group-mate recruitment and behaviour monitoring.
Animal cognition. 08/2009;
Animals living in groups have to make consensus decisions and communicate with each other about the time, or the direction, in which to move. In some species, the process relies on the proposition of a single individual, i.e. a first individual suggests a movement and the other group members decide ... [more] Animals living in groups have to make consensus decisions and communicate with each other about the time, or the direction, in which to move. In some species, the process relies on the proposition of a single individual, i.e. a first individual suggests a movement and the other group members decide whether or not to join this individual. In Tonkean (Macaca tonkeana) and rhesus macaques (Macaca mulatta), it has been observed that this first individual displays specific signals at departure. In this paper, we aimed to explore the function of such behaviours, i.e. if these behaviours were recruitment signals or only cues about the motivation of the first departed individual. We carried out temporal analyses and studied the latencies of the first departed individual's behaviours and of the joining of other group members. We also assessed whether the social style of a species in terms of dominance and kinship relationships influenced the patterns of signal emissions. We then analyzed how the first departed individual decided to make a pause or to stop it according to the identities of group members that joined the collective movement. Results showed that Tonkean macaques and rhesus macaques seemed to use back-glances to monitor the joining of other group members and pauses to recruit such individuals. This was especially the case for highly socially affiliated individuals in Tonkean macaques and kin-related individuals in rhesus macaques. Moreover, back-glances and pauses disappeared when such individuals joined the first departed individual. From these results, we suggested that such behaviour could be considered intentional. Such findings could not be highlighted without temporal analyses and accurate observations on primate groups in semi-free ranging conditions.
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4.11Impact points
Collective decision-making in white-faced capuchin monkeys.
Proceedings. Biological sciences / The Royal Society. 08/2009;
In group-living animals, collective movements are a widespread phenomenon and occur through consensus decision. When one animal proposes a direction for group movement, the others decide to follow or not and hence take part in the decision-making process. This paper examines the temporal spread of i... [more] In group-living animals, collective movements are a widespread phenomenon and occur through consensus decision. When one animal proposes a direction for group movement, the others decide to follow or not and hence take part in the decision-making process. This paper examines the temporal spread of individual responses after the departure of a first individual (the initiator) in a semi-free ranging group of white-faced capuchins (Cebus capucinus). We analysed 294 start attempts, 111 succeeding and 183 failing. Using a modelling approach, we have demonstrated that consensus decision-making for group movements is based on two complementary phenomena in this species: firstly, the joining together of group members thanks to a mimetic process; and secondly, a modulation of this phenomenon through the propensity of the initiator to give up (i.e. cancellation rate). This cancellation rate seems to be directly dependent upon the number of followers: the greater this number is, the lower the cancellation rate is seen to be. The coupling between joining and cancellation rates leads to a quorum: when three individuals join the initiator, the group collectively moves. If the initiator abandons the movement, this influences the joining behaviour of the other group members, which in return influences the initiator's behaviour. This study demonstrates the synergy between the initiator's behaviour and the self-organized mechanisms underlying group movements.
Following (3)
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Cédric Sueur
Université de Strasbourg -
Olivier Pascalis
Université Pierre Mendès France - Grenoble 2 -
Frédéric Bertrand
Université de Strasbourg
Topics (3)
