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  • Publication
    Métadonnées seulement
  • Publication
    Accès libre
    Do cleaner fish learn to feed against their preference in a reverse reward contingency task?
    (2010)
    Danisman, Evin
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    The ability to control impulsive behaviour has been studied in animals with a standard test in which subjects need to choose the smaller of two food items in order to receive the larger one (reverse reward contingency). As a variety of mammals that have been tested so far (mostly primates) have great difficulties to solve the task, it has been proposed that it is generally cognitively demanding. However, according to an ecological approach to cognition, a species’ ability to solve the task should not depend on its general cognitive abilities but on whether its ecology causes selective pressure on the ability to restrain foraging behaviour. We tested this hypothesis using the cleaner wrasse (Labroides dimidiatus), a fish species that feeds against its preference in nature when engaging in cleaning interactions with so called ‘client fish’. None of the eight tested individuals learned to choose a non-preferred item after 200 trials. In a subsequent test, one subject learned to respond correctly in a large or none contingency task (only the choice of the small food was rewarded). After a short re-experience treatment, this individual learned to solve the reverse reward task after 30 trials. In conclusion, we did not find support for the general idea that interactions with clients prepared cleaners to quickly solve a reverse reward test. However, the results suggest that the potential to solve a reverse reward contingency may not be restricted to mammals but could be present also in a fish species in which the problem of choosing a non-preferred food over a preferred one is an ever present challenge in nature.
  • Publication
    Accès libre
    Distinguishing four fundamental approaches to the evolution of helping
    The evolution and stability of helping behaviour has attracted great research efforts across disciplines. However, the field is also characterized by a great confusion over terminology and a number of disagreements, often between disciplines but also along taxonomic boundaries. In an attempt to clarify several issues, we identify four distinct research fields concerning the evolution of helping: (1) basic social evolution theory that studies helping within the framework of Hamilton’s inclusive fitness concept, i.e. direct and indirect benefits, (2) an ecological approach that identifies settings that promote life histories or interaction patterns that favour unconditional cooperative and altruistic behaviour, e.g. conditions that lead to interdependency or interactions among kin, (3) the game theoretic approach that identifies strategies that provide feedback and control mechanisms (protecting from cheaters) favouring cooperative behaviour (e.g. pseudo-reciprocity, reciprocity), and (4) the social scientists’ approach that particularly emphasizes the special cognitive requirements necessary for human cooperative strategies. The four fields differ with respect to the ‘mechanisms’ and the ‘conditions’ favouring helping they investigate. Other major differences concern a focus on either the life-time fitness consequences or the immediate payoff consequences of behaviour, and whether the behaviour of an individual or a whole interaction is considered. We suggest that distinguishing between these four separate fields and their complementary approaches will reduce misunderstandings, facilitating further integration of concepts within and across disciplines.
  • Publication
    Accès libre
    Integrating cooperative breeding into theoretical concepts of cooperation
    (2007) ;
    Johnstone, Rufus A.
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    Russell, Andrew F.
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    In cooperative breeding systems, some individuals help to raise offspring that are not their own. While early explanations for such altruistic behaviour were predominantly based on kin selection, recent evidence suggests that direct benefits may be important in the maintenance of cooperation. To date, however, discussions of cooperative breeding have made little reference to more general theories of cooperation between unrelated individuals (while these theories rarely address cooperative breeding). Here, we attempt to integrate the two fields. We identify four key questions that can be used to categorise different mechanisms for the maintenance of cooperative behaviour: (1) whether or not individuals invest in others; (2) whether or not this initial investment elicits a return investment by the beneficiary; (3) whether the interaction is direct, i.e. between two partners, or indirect (involving third parties) and (4) whether only actions that increase the fitness of the partner or also fitness reducing actions (punishment) are involved in the interaction. Asking these questions with regards to concepts in the literature on cooperative breeding, we found that (a) it is often straightforward to relate these concepts to general mechanisms of cooperation, but that (b) a single term (such as ‘pay-to-stay’, ‘group augmentation’ or ‘prestige’) may sometimes subsume two or more distinct mechanisms, and that (c) at least some mechanisms that are thought to be important in cooperative breeding systems have remained largely unexplored in the theoretical literature on the evolution of cooperation. Future theoretical models should incorporate asymmetries in power and pay off structure caused for instance by dominance hierarchies or partner choice, and the use of N-player games. The key challenges for both theoreticians and empiricists will be to integrate the hitherto disparate fields and to disentangle the parallel effects of kin and non-kin based mechanisms of cooperation.
  • Publication
    Accès libre
    On the further integration of cooperative breeding and cooperation theory
    (2007) ;
    Russell, Andrew F.
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    Johnstone, Rufus A.
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    We present a synopsis about the commentaries to the target article “Integrating cooperative breeding into theoretical concepts of cooperation”, in which we attempted to integrate general mechanisms to explain cooperative behaviour among unrelated individuals with classic concepts to explain helping behaviour in cooperative breeders that do not invoke kin-based benefits. Here we (1) summarize the positions of the commentators concerning the main issues we raised in the target article and discuss important criticisms and extensions. (2) We relate our target article to some recent reviews on the evolution of cooperation and, (3) clarify how we use terminology with regard to cooperation and cooperative behaviour. (4) We discuss several aspects that were raised with respect to cooperative interactions including by-product mutualism, generalised reciprocity and multi-level selection and, (5) examine the alternatives to our classification scheme as proposed by some commentaries. (6) Finally, we highlight several aspects that might hinder the application of game theoretical mechanisms of cooperation in cooperatively breeding systems. Although there is broad agreement that cooperative breeding theory should be integrated within the more general concepts of cooperation, there is some debate about how this may be achieved. We conclude that the contributions in this special issue provide a fruitful first step and ample suggestions for future directions with regard to a more unified framework of cooperation in cooperative breeders.
  • Publication
    Accès libre
    Conflict management in free-ranging wolves, Canis lupus
    Baan, Candice
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    Smith, Douglas W
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    Molnar, Barbara
    Individuals should invest in conflict management when the costs of conflicts outweigh their benefits. We investigated whether free-ranging wolves engage in conflict resolution. We predicted that reconciliation and consolation should occur because pack members are highly interdependent upon each other owing to the benefits that group members derive from cooperative breeding, cooperative hunting and cooperation in between-group conflicts. As within-group conflict in wolves is low, in accordance with tolerant dominance relationships among pack members, we also predicted a high conciliatory tendency. We collected behavioural data from two packs in Yellowstone National Park (U.S.A.). We report reconciliation, mainly initiated by victims and directed towards aggressors, and solicited and unsolicited consolation. As predicted, the conciliatory tendency was high and comparable to the values reported in primate species with a tolerant dominance style. We suggest that conflict management is favoured in wolves, and more generally in species with a sufficiently high degree of interdependence among group members, as interdependence can explain investment in conflict mitigation without the need to invoke particular relationships of mutual value.