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C. K. Hemelrijk,. (1999). An individual-orientated model of the emergence of despotic and egalitarian societies. Proc. Roy. Soc. Lond. B Biol. Sci., 266(1417), 361.
Abstract: Single behavioural differences between egalitarian and despotic animal societies are often assumed to reflect specific adaptations. However, in the present paper, I will show in an individual-orientated model, how many behavioural traits of egalitarian and despotic virtual societies arise as emergent characteristics. The artificial entities live in a homogeneous world and only aggregate, and upon meeting one another and may perform dominance interactions in which the effects of winning and losing are self-reinforcing. The behaviour of these entities is studied in a similar way to that of real animals. It will be shown that by varying the intensity of aggression only, one may switch from egalitarian to despotic virtual societies. Differences between the two types of society appear to correspond closely to those between despotic and egalitarian macaque species in the real world. In addition, artificial despotic societies show a clearer spatial centrality of dominants and, counter-intuitively, more rank overlap between the sexes than the egalitarian ones. Because of the correspondence with patterns in real animals, the model makes it worthwhile comparing despotic and egalitarian species for socio-spatial structure and rank overlap too. Furthermore, it presents us with parsimonious hypotheses which can be tested in real animals for patterns of aggression, spatial structure and the distribution of social positive and sexual behaviour.
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Swaddle, J. P., & Witter, M. S. (1995). Chest Plumage, Dominance and Fluctuating Asymmetry in Female Starlings. Proc. Roy. Soc. Lond. B Biol. Sci., 260(1358), 219–223.
Abstract: It has been proposed that levels of fluctuating asymmetry (FA) may be used in establishing and maintaining dominance hierarchies, as asymmetry reflects aspects of individual quality. However, previous manipulations of FA have failed to reveal that the level or outcome of agonistic intra-sexual interactions are affected by levels of FA. In female European starlings (Sturnus vulgaris), correlational data suggest that FA of the speckled chest plumage may be related to dominance status. These data are confounded, however, by total number of spots on the chest and the proportion of the chest that is white, both of which positively covary with chest asymmetry. Thus, we deconfounded the effects of these plumage traits on dominance by experimentally manipulating the number of spots and spot number asymmetry in a factorial design. The results indicated that dominance is influenced by the number of spots on the chest, but not by spot asymmetry. Birds with spottier chests were dominant over birds with experimentally decreased spot number. We suggest that female starlings' chests are exposed to extensive abrasion throughout the breeding season and so are susceptible to damage asymmetries that may mask the `true' fluctuating asymmetry of the trait. This may devalue the use of chest asymmetry as a quality indicator. Spottier chests may be costly to maintain, in part because of increased susceptibility to abrasion, and so may be a better indicator of quality than asymmetry.
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Johnstone, R. A., & Dugatkin, L. A. (2000). Coalition formation in animals and the nature of winner and loser effects. Proc. Roy. Soc. Lond. B Biol. Sci., 267(1438), 17–21.
Abstract: Coalition formation has been documented in a diverse array of taxa, yet there has been little formal analysis of polyadic interactions such as coalitions. Here, we develop an optimality model which examines the role of winner and loser effects in shaping coalition formation. We demonstrate that the predicted patterns of alliances are strongly dependent on the way in which winner and loser effects change with contestant strength. When winner and loser effects decrease with the resource-holding power (RHP) of the combatants, coalitions will be favoured between the strongest members of a group, but not between the weakest. If, in contrast, winner and loser effects increase with RHP, exactly the opposite predictions emerge. All other things being equal, intervention is more likely to prove worthwhile when the beneficiary of the aid is weaker (and its opponent is stronger), because the beneficiary is then less likely to win without help. Consequently, intervention is more probable when the impact of victory on the subsequent performance of a combatant increases with that individual's strength because this selects for intervention in favour of weaker combatants. The published literature on hierarchy formation does not reveal how winner and loser effects actually change with contestant strength and we therefore hope that our model will spur others to collect such data; in this light we suggest an experiment which will help to elucidate the nature of winner and loser effects and their impact on coalition formation in animals.
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Griffiths, S. W., Brockmark, S., Höjesjö, J., & Johnsson, J. I. (2004). Coping with divided attention: the advantage of familiarity. Proc. Roy. Soc. Lond. B Biol. Sci., 271(1540), 695–699.
Abstract: The ability of an animal to perform a task successfully is limited by the amount of attention being simultaneously focused on other activities. One way in which individuals might reduce the cost of divided attention is by preferentially focusing on the most beneficial tasks. In territorial animals where aggression is lower among familiar individuals, the decision to associate preferentially with familiar conspecifics may therefore confer advantages by allowing attention to be switched from aggression to predator vigilance and feeding. Wild juvenile brown trout were used to test the prediction that familiar fishes respond more quickly than unfamiliar fishes to a simulated predator attack. Our results confirm this prediction by demonstrating that familiar trout respond 14% faster than unfamiliar individuals to a predator attack. The results also show that familiar fishes consume a greater number of food items, foraging at more than twice the rate of unfamiliar conspecifics. To the best of our knowledge, these results provide the first evidence that familiarity–biased association confers advantages through the immediate fitness benefits afforded by faster predator–evasion responses and the long–term benefits provided by increased feeding opportunities.
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Tebbich, S., Taborsky, M., Fessl, B., & Blomqvist, D. (2001). Do woodpecker finches acquire tool-use by social learning? Proc. Roy. Soc. Lond. B Biol. Sci., 268(1482), 2189–2193.
Abstract: Tool–use is widespread among animals, but except in primates the development of this behaviour is poorly known. Here, we report on the first experimental study to our knowledge of the mechanisms underlying the acquisition of tool–use in a bird species. The woodpecker finch Cactospiza pallida, endemic to the Galápagos Islands, is a famous textbook example of tool–use in animals. This species uses modified twigs or cactus spines to pry arthropods out of tree holes. Using nestlings and adult birds from the field, we tested experimentally whether woodpecker finches learn tool–use socially. We show that social learning is not essential for the development of tool–use: all juveniles developed tool–use regardless of whether or not they had a tool–using model. However, we found that not all adult woodpecker finches used tools in our experiments. These non–tool–using individuals also did not learn this task by observing tool–using conspecifics. Our results suggest that tool–use behaviour depends on a very specific learning disposition that involves trial–and–error learning during a sensitive phase early in ontogeny.
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Reeve, H. K. (1997). Evolutionarily stable communication between kin: a general model. Proc. Roy. Soc. Lond. B Biol. Sci., 264((1384)). Retrieved May 19, 2024, from http://dx.doi.org/10.1098/rspb.1997.0143
Abstract: At present, the most general evolutionary theory of honest communication is Grafen's model of Zahavi's 'handicap' signalling system, in which honesty of signals about the signaller's quality (e.g. mate suitability or fighting ability) is maintained by the differentially high cost of signals to signallers having lower quality. The latter model is here further generalized to include any communication between signallers and receivers that are genetically related (e.g. parents and begging offspring, cooperative or competing siblings). Signalling systems involving relatives are shown to be evolutionarily stable, despite a potential pay-off for false signalling, if the Zahavian assumption of differential signal costs holds and there are diminishing reproductive returns to the signaller as the receiver's assessed value of its attribute increases, or if, regardless of whether the Zahavian assumption holds, signallers with high values of the attribute benefit more from a given receiver assessment than signallers with low values (e.g. begging chicks that are hungrier benefit more from being fed). In stable systems of signalling among kin, it is also shown to be generally true that (i) levels of signalling and thus observed signal costs will decline as relatedness increases or as the receiver's reproductive penalty for erroneous assessment increases, and (ii) receivers will consistently, altruistically overestimate the true value of the signalled attribute.
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Witter, M. S., & Swaddle, J. P. (1994). Fluctuating Asymmetries, Competition and Dominance. Proc. Roy. Soc. Lond. B Biol. Sci., 256(1347), 299–303.
Abstract: Levels of fluctuating asymmetry (FA) in the primary feathers of European starlings, Sturnus vulgaris, have been shown to be sensitive to nutritional and energetic stress. Furthermore, between-individual variation in plumage FA has been found to be related to social dominance, even without social interactions during feather growth, with dominant birds exhibiting the highest levels of FA. Here we examine whether the relation between dominance and FA differs when birds are housed in social groups, under different degrees of competition for food, during moult. We reason that dominants should derive a greater benefit from their social status as competition for food increases. Our results support this proposition. The relation between dominance and FA differed significantly according to the degree of competition for food. However, in no cases did the dominants exhibit lower levels of FA than subdominants. When competition for food was low, dominants had higher levels of FA than subdominants. When competition for food was high, there was no systematic relation between dominance and FA. These results suggest that dominants may only derive a net benefit from their social status, under the circumstances of our experiment, during severe conditions of competition.
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Bode, N. W. F., Faria, J. J., Franks, D. W., Krause, J., & Wood, A. J. (2010). How perceived threat increases synchronization in collectively moving animal groups. Proc. Roy. Soc. Lond. B Biol. Sci., 277(1697), 3065–3070.
Abstract: Nature is rich with many different examples of the cohesive motion of animals. Previous attempts to model collective motion have primarily focused on group behaviours of identical individuals. In contrast, we put our emphasis on modelling the contributions of different individual-level characteristics within such groups by using stochastic asynchronous updating of individual positions and orientations. Our model predicts that higher updating frequency, which we relate to perceived threat, leads to more synchronized group movement, with speed and nearest-neighbour distributions becoming more uniform. Experiments with three-spined sticklebacks (Gasterosteus aculeatus) that were exposed to different threat levels provide strong empirical support for our predictions. Our results suggest that the behaviour of fish (at different states of agitation) can be explained by a single parameter in our model: the updating frequency. We postulate a mechanism for collective behavioural changes in different environment-induced contexts, and explain our findings with reference to confusion and oddity effects.
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Oliveira, R. F., McGregor, P. K., & Latruffe, C. (1998). Know thine enemy: fighting fish gather information from observing conspecific interactions. Proc. Roy. Soc. Lond. B Biol. Sci., 265(1401), 1045–1049.
Abstract: Many of the signals that animals use to communicate transmit relatively large distances and therefore encompass several potential signallers and receivers. This observation challenges the common characterization of animal communication systems as consisting of one signaller and one receiver. Furthermore, it suggests that the evolution of communication behaviour must be considered as occurring in the context of communication networks rather than dyads. Although considerations of selection pressures acting upon signallers in the context of communication networks have rarely been expressed in such terms, it has been noted that many signals exchanged during aggressive interactions will transmit far further than required for information transfer between the individuals directly involved, suggesting that these signals have been designed to be received by other, more distant, individuals. Here we consider the potential for receivers in communication networks to gather information, one aspect of which has been termed eavesdropping. We show that male Betta splendens monitor aggressive interactions between neighbouring conspecifics and use the information on relative fighting ability in subsequent aggressive interactions with the males they have observed.
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Bugnyar, T. (2011). Knower–guesser differentiation in ravens: others' viewpoints matter. Proc. Roy. Soc. Lond. B Biol. Sci., 278(1705), 634–640.
Abstract: Differentiating between individuals with different knowledge states is an important step in child development and has been considered as a hallmark in human evolution. Recently, primates and corvids have been reported to pass knower–guesser tasks, raising the possibility of mental attribution skills in non-human animals. Yet, it has been difficult to distinguish ‘mind-reading’ from behaviour-reading alternatives, specifically the use of behavioural cues and/or the application of associatively learned rules. Here, I show that ravens (Corvus corax) observing an experimenter hiding food are capable of predicting the behaviour of bystanders that had been visible at both, none or just one of two caching events. Manipulating the competitors' visual field independently of the view of the test-subject resulted in an instant drop in performance, whereas controls for behavioural cues had no such effect. These findings indicate that ravens not only remember whom they have seen at caching but also take into account that the other's view was blocked. Notably, it does not suffice for the birds to associate specific competitors with specific caches. These results support the idea that certain socio-ecological conditions may select for similar cognitive abilities in distantly related species and that some birds have evolved analogous precursors to a human theory-of-mind.
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