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Author |
Broom, M. |
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Title |
A unified model of dominance hierarchy formation and maintenance |
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Journal Article |
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2002 |
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Journal of theoretical biology |
Abbreviated Journal |
J. Theor. Biol. |
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219 |
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1 |
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63-72 |
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Animals; *Behavior, Animal; Feeding Behavior; *Models, Psychological; *Social Dominance; Social Environment |
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In many different species it is common for animals to spend large portions of their lives in groups. Such groups need to divide available resources amongst the individuals they contain and this is often achieved by means of a dominance hierarchy. Sometimes hierarchies are stable over a long period of time and new individuals slot into pre-determined positions, but there are many situations where this is not so and a hierarchy is formed out of a group of individuals meeting for the first time. There are several different models both of the formation of such dominance hierarchies and of already existing hierarchies. These models often treat the two phases as entirely separate, whereas in reality, if there is a genuine formation phase to the hierarchy, behaviour in this phase will be governed by the rewards available, which in turn depends upon how the hierarchy operates once it has been formed. This paper describes a method of unifying models of these two distinct phases, assuming that the hierarchy formed is stable. In particular a framework is introduced which allows a variety of different models of each of the two parts to be used in conjunction with each other, thus enabling a wide range of situations to be modelled. Some examples are given to show how this works in practice. |
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Centre for Statistics and Stochastic Modelling, School of Mathematical Sciences, University of Sussex, Falmer, Brighton, BN1 9QH, U.K. m.broom@sussex.ac.uk |
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0022-5193 |
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PMID:12392975 |
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refbase @ user @ |
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439 |
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Dugatkin, L.A.; Perlin, M.; Atlas, R. |
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Title |
The Evolution of Group-beneficial Traits in the Absence of Between-group Selection |
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Journal Article |
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2003 |
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Journal of Theoretical Biology |
Abbreviated Journal |
J. Theor. Biol. |
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220 |
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1 |
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67-74 |
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One specific prediction emerging from trait-group models of natural selection is that when individuals possess traits that benefit other group members, natural selection will favor “cheating” (i.e. not possessing the group-beneficial trait) within groups. Cheating is selected within groups because it allows individuals to avoid bearing the relative costs typically associated with group-beneficial traits, but to still reap the benefits associated with the acts of other group members. Selection between groups favors traits that benefit other group members. The relative strength of within- and between-group selection then determines the equilibrium frequency of those who produce group-beneficial traits and those that do not. Here we demonstrate that individual-level selection, that is selection within groups can also produce an intermediate frequency of such group-beneficial traits by frequency-dependent selection. The models we develop are general in nature, but were inspired by the evolution of antibiotic resistance in bacteria. The theory developed here is distinct from prior work that relies on reciprocity or kinship per'se to achieve cooperation and altruism among group members. |
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491 |
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James, R.; Bennett, P.G.; Krause, J. |
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Title |
Geometry for mutualistic and selfish herds: the limited domain of danger |
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Journal Article |
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2004 |
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Journal of Theoretical Biology |
Abbreviated Journal |
J. Theor. Biol. |
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228 |
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1 |
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107-113 |
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Aggregation; Selfish herd; Limited domains |
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We present a two-dimensional individual-based model of aggregation behaviour in animals by introducing the concept of a “limited domain of danger”, which represents either a limited detection range or a limited attack range of predators. The limited domain of danger provides a suitable framework for the analysis of individual movement rules under real-life conditions because it takes into account the predator's prey detection and capture abilities. For the first time, a single geometrical construct can be used to analyse the predation risk of both peripheral and central individuals in a group. Furthermore, our model provides a conceptual framework that can be equally applied to aggregation behaviour and refuge use and thus presents a conceptual advance on current theory that treats these antipredator behaviours separately. An analysis of individual movement rules using limited domains of danger showed that the time minimization strategy outcompetes the nearest neighbour strategy proposed by Hamilton's (J. Theor. Biol. 31 (1971) 295) selfish herd model, whereas a random strategy confers no benefit and can even be disadvantageous. The superior performance of the time minimization strategy highlights the importance of taking biological constraints, such as an animal's orientation relative to its neighbours, into account when searching for efficient movement rules underlying the aggregation process. |
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refbase @ user @ |
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552 |
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Author |
Parker, G.A. |
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Title |
Assessment strategy and the evolution of fighting behaviour |
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Journal Article |
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Year |
1974 |
Publication |
Journal of Theoretical Biology |
Abbreviated Journal |
J. Theor. Biol. |
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47 |
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1 |
Pages |
223-243 |
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The view is examined that the adaptive value of conventional aspects of fighting behaviour is for assessment of relative RHP (resource holding power) of the combatants. Outcomes of aggressive disputes should be decided by each individual's fitness budget available for expenditure during a fight (determined by the fitness difference between adoption of alternative strategies, escalation or withdrawal without escalation) and on the rate of expenditure of the fitness budget if escalation occurs (determined by the RHPs of the combatants). Thus response thresholds for alternative strategies (“assessments”) will be determined by natural selection on a basis of which opponent is likely to expend its fitness budget first, should escalation occur. This “loser” should retreat (before escalation) and the winner should stay in possession of the resource. Many aggressive decisions depend on whether one is a resource holder, or an attacker. Assuming the RHP of the combatants to be equal, there are many instances of fitness pay-off imbalances between holder and attacker which should weight the dispute outcome in favour of one or other opponent by allowing it a greater expendable fitness budget. Usually the weighting favours the holder; the attacker therefore needs a correspondingly higher RHP before it may be expected to win. This is not invariably the case, and much observed data fits the predictions of this sort of model. If assessments are perfect and budget expenditure rates exactly predictable, then there would never seem to be any case for escalation. Escalation can be explained in terms of injury inflictions (expenditures) occurring as discrete events; i.e. as “bouts” won or lost during fighting. Assessment can give only a probabilistic prediction of the outcome of a bout. A simple model is developed to investigate escalation situations. Each combatant assesses relative RHP; this correlates with an absolute probability of winning the next bout (cabs). The stake played for is infliction of loss of RHP and is determined by the fitness budgets of the opponents. (Each individual plays for the withdrawal of its opponent.) This defines a critical probability of winning (ccrit) for each combatant, above which escalation is the favourable strategy (cabs > ccrit) and below which withdrawal is favourable (cabs < ccrit). Escalation should occur only where cabs-ccrit is positive for both combatants. This model gives predictions compatible with the observations, indicating that RHP loss alone can be adequate to explain withdrawal: escalation behaviour. Withdrawal tendency will be increased by low searching costs. Escalations should be restricted to closely matched RHP opponents if RHP disparity is the major imbalance. Outside the “escalation range” of a given individual, the higher RHP individual wins and the lower one loses (i.e. it should withdraw after conventional display). RHP disparity and holder: attacker imbalance should both interact to shape the observed pattern, though their relative importances will depend on species and situation. In some instances selection may favour immediate withdrawal from an occupied territory even without assessment of RHP. |
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0022-5193 |
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Equine Behaviour @ team @ |
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4935 |
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Author |
Gueron, S.; Levin, S.A.; Rubenstein, D.I. |
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Title |
The Dynamics of Herds: From Individuals to Aggregations |
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Journal Article |
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Year |
1996 |
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Journal of Theoretical Biology |
Abbreviated Journal |
J. Theor. Biol. |
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182 |
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1 |
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85-98 |
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The dynamic behavior of small herds is investigated by means of simulations of two-dimensional discrete-stochastic models. An individual-based approach is used to relate collective behavior to individual decisions. In our model, the motion of an individual in a herd is assumed to be the combined result of both density-independent and density-dependent decisions, in the latter case based on the influence of surrounding neighbors; assumed decision rules are hierarchical, balancing short range repulsion against long-range attraction. The probability of fragmentation of the model herd depends on parameter values. We explore the variety and characteristics of spatial patterns that develop during migration, for herds that are homogeneous and heterogeneous regarding intrinsic walking speeds. Group integrity can be maintained even in mixed populations, but fragmentation results for these more easily than for a homogeneous herd. Observations of natural populations suggest that animals move away from individuals that intrude too closely into their environment, but are attracted to individuals at a distance. Between these extremes, there appears to be a neutral zone, within which other individuals engender no response. We explore the importance of this neutral zone, and offer evolutionary interpretations. In particular, the neutral zone, if not too large, permits the individual to remain in contact with the herd, while reducing the frequency with which acceleration or deceleration must be undertaken. This offers obvious energetic benefits. |
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0022-5193 |
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Equine Behaviour @ team @ |
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5253 |
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Couzin, I.D.; Krause, J.; James, R.; Ruxton, G.D.; Franks, N.R. |
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Title |
Collective Memory and Spatial Sorting in Animal Groups |
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Journal Article |
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2002 |
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Journal of Theoretical Biology |
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J. Theor. Biol. |
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218 |
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1 |
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1-11 |
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We present a self-organizing model of group formation in three-dimensional space, and use it to investigate the spatial dynamics of animal groups such as fish schools and bird flocks. We reveal the existence of major group-level behavioural transitions related to minor changes in individual-level interactions. Further, we present the first evidence for collective memory in such animal groups (where the previous history of group structure influences the collective behaviour exhibited as individual interactions change) during the transition of a group from one type of collective behaviour to another. The model is then used to show how differences among individuals influence group structure, and how individuals employing simple, local rules of thumb, can accurately change their spatial position within a group (e.g. to move to the centre, the front, or the periphery) in the absence of information on their current position within the group as a whole. These results are considered in the context of the evolution and ecological importance of animal groups. |
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0022-5193 |
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Equine Behaviour @ team @ |
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5310 |
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Mesterton-Gibbons, M.; Gavrilets, S.; Gravner, J.; Akçay, E. |
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Title |
Models of coalition or alliance formation |
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Journal Article |
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2011 |
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Journal of Theoretical Biology |
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J. Theor. Biol. |
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274 |
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1 |
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187-204 |
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Game theory; Cooperation |
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More than half a century has now elapsed since coalition or alliance formation theory (CAFT) was first developed. During that time, researchers have amassed a vast amount of detailed and high-quality data on coalitions or alliances among primates and other animals. But models have not kept pace, and more relevant theory is needed. In particular, even though CAFT is primarily an exercise in polyadic game theory, game theorists have devoted relatively little attention to questions that motivate field research, and much remains largely unexplored. The state of the art is both a challenge and an opportunity. In this review we describe a variety of game-theoretic and related modelling approaches that have much untapped potential to address the questions that field biologists ask. |
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Equine Behaviour @ team @ |
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5322 |
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Hamilton, W.D. |
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Title |
The genetical evolution of social behaviour. I |
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Journal Article |
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Year |
1964 |
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Journal of Theoretical Biology |
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J. Theor. Biol. |
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7 |
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1and 2 |
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1-52 |
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*Behavior; *Genetics; Humans; *Models, Theoretical |
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A genetical mathematical model is described which allows for interactions between relatives on one another's fitness. Making use of Wright's Coefficient of Relationship as the measure of the proportion of replica genes in a relative, a quantity is found which incorporates the maximizing property of Darwinian fitness. This quantity is named “inclusive fitness”. Species following the model should tend to evolve behaviour such that each organism appears to be attempting to maximize its inclusive fitness. This implies a limited restraint on selfish competitive behaviour and possibility of limited self-sacrifices.
Special cases of the model are used to show (a) that selection in the social situations newly covered tends to be slower than classical selection, (b) how in populations of rather non-dispersive organisms the model may apply to genes affecting dispersion, and (c) how it may apply approximately to competition between relatives, for example, within sibships. Some artificialities of the model are discussed. |
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0022-5193 |
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PMID:5875341 |
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Equine Behaviour @ team @ |
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5160 |
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Fishman, M.A. |
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Title |
Predator Inspection: Closer Approach as a Way to Improve Assessment of Potential Threats |
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1999 |
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Journal of Theoretical Biology |
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J. Theor. Biol. |
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196 |
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2 |
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225-235 |
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When detecting a predator, some prey animals respond in a counterintuitive fashion by approaching, rather than fleeing, that potential threat of extinction. This seemingly paradoxical behaviour, known aspredator inspection, has been reported for a wide variety of taxa--and therefore can be assumed to be adaptive. However, the view of predator inspection as a paradoxical behaviour rests on two implicit assumptions: (a) initial predator detecting is unambiguous, with no uncertainty in discriminating between hunting and non hunting members of predator species, or members of predator species and unrelated phenomena; (b) the costs of flight are negligible relative to the risk of predation. Upon reflection assumption (a) is not really tenable. Whereas assumption (b) is not consistent with experimental evidence [Godin & Crossman (1994)Behav. Ecol. Sociobiol.34,359-366]. Given that predator detection is ambiguous and the costs of flight are not negligible, a prey individual may benefit by a closer approach to the source of the alarming signals, thus improving its assessment of the situation--despite the increased risk of predation. In this paper, the above statement is given rigor by reformulating the problem in game theoretical terms. The results indicate that a prey will minimize its costs by performing predator inspection whenever its degree of certainty regarding predator identification and/or assessment of its intentions is less than a threshold, which is determined by the model's parameters. |
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Reluga, T.C.; Viscido, S. |
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Simulated evolution of selfish herd behavior |
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2005 |
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Journal of Theoretical Biology |
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J. Theor. Biol. |
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234 |
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2 |
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213-225 |
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Selfish herd; Behavior; Evolution; Predation risk |
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Single species aggregations are a commonly observed phenomenon. One potential explanation for these aggregations is provided by the selfish herd hypothesis, which states that aggregations result from individual efforts to reduce personnel predation risk at the expense of group-mates. Not all movement rules based on the selfish herd hypothesis are consistent with observed animal behavior. Previous work has shown that herd-like aggregations are not generated by movement rules limited to local interactions between nearest neighbors. Instead, rules generating realistic herds appear to require delocalized interactions. To date, it has been an open question whether or not the necessary delocalization can emerge from local interactions under natural selection. To address this question, we study an individual-based model with a single quantitative genetic trait that controls the influence of neighbors as a function of distance. The results indicate that predation-based selection can increase the influence of distant neighbors relative to near neighbors. Our results lend support for the idea that selfish herd behavior can arise from localized movement rules under natural selection. |
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