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Author (up) Clutton-Brock, T.H.; Parker, G.A. url  doi
openurl 
  Title Punishment in animal societies Type Journal Article
  Year 1995 Publication Abbreviated Journal Nature  
  Volume 373 Issue 6511 Pages 209-216  
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  Abstract Although positive reciprocity (reciprocal altruism) has been a focus of interest in evolutionary biology, negative reciprocity (retaliatory infliction of fitness reduction) has been largely ignored. In social animals, retaliatory aggression is common, individuals often punish other group members that infringe their interests, and punishment can cause subordinates to desist from behaviour likely to reduce the fitness of dominant animals. Punishing strategies are used to establish and maintain dominance relationships, to discourage parasites and cheats, to discipline offspring or prospective sexual partners and to maintain cooperative behaviour.  
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  Notes 10.1038/373209a0 Approved no  
  Call Number Equine Behaviour @ team @ Serial 4838  
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Author (up) Clutton-Brock, T.H.; Parker, G.A. url  doi
openurl 
  Title Sexual coercion in animal societies Type Journal Article
  Year 1995 Publication Animal Behaviour. Abbreviated Journal Anim. Behav.  
  Volume 49 Issue 5 Pages 1345-1365  
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  Abstract In a wide range of animal species, males coerce females to mate with them, either by physically forcing them to mate, by harassing them until they mate or by punishing persistent refusal to mate. The first section of this paper argues that the possibility of forced copulation can generate arms races between males and females that may have substantial costs to both sexes. In the second section, it is suggested that sexual harassment commonly represents a `war of attrition' between the sexes; existing game theory models that may apply to sexual conflict over mating decisions are reviewed. The third section develops a simple prospective model for the evolution of intimidation by punishment in situations where males can raise the probability that females will accept their advances in future by punishing them for refusal to mate. Where the benefits of sexual coercion to males are high, all three male strategies may develop to a point where they have substantial costs to females. In the final section, evidence that female behaviour is adapted to minimizing these costs is reviewed.  
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  Notes Approved no  
  Call Number refbase @ user @ Serial 757  
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Author (up) Parker, G.A. url  doi
openurl 
  Title Assessment strategy and the evolution of fighting behaviour Type Journal Article
  Year 1974 Publication Journal of Theoretical Biology Abbreviated Journal J. Theor. Biol.  
  Volume 47 Issue 1 Pages 223-243  
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  Abstract 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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  ISSN 0022-5193 ISBN Medium  
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  Notes Approved no  
  Call Number Equine Behaviour @ team @ Serial 4935  
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Author (up) Parker, G.A.; MacNair, M.R. url  doi
openurl 
  Title Models of parent-offspring conflict. I. Monogamy Type Journal Article
  Year 1978 Publication Animal Behaviour. Abbreviated Journal Anim. Behav.  
  Volume 26 Issue Pages 97-110  
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  Abstract Theoretical models for Trivers (1974) concept of parent-offspring conflict are examined for species in which the effects of the conflict are felt by full sibs. A rare conflictor gene will spread if Image , whereÆ’(m) is the fitness gained by a conflictor relative to a non-conflictor offspring (Æ’(m) >1), and m is the amount of parental investment taken by a conflictor relative to m = 1 for a non-conflictor. The range of m alleles which can spread against the parent optimum decreases as the cost to the parent increases until a point is reached where there is no conflict of evolutionary interests. There would be no polymorphism for conflictor: non-conflictor alleles unless special conditions prevail. The conflictor allele which spreads most rapidly as a rare mutant against the parental optimum is not an evolutionarily stable strategy (ESS). The ESS for parent-offspring conflict in monogamous species has m0 = Æ’(m0)/2[dÆ’(m0)/dm0]. The analytical solutions are confirmed throughout by simulations.  
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  Notes 10.1016/0003-3472(78)90009-X Approved no  
  Call Number Equine Behaviour @ team @ Serial 4901  
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Author (up) Parker, G.A.; Rubenstein, D.I. url  doi
openurl 
  Title Role assessment, reserve strategy, and acquisition of information in asymmetric animal conflicts Type Journal Article
  Year 1981 Publication Animal Behaviour. Abbreviated Journal Anim. Behav.  
  Volume 29 Issue 1 Pages 221-240  
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  Abstract It was formerly argued that alternative evolutionarily stable strategies (ESSs) are possible for animal contests characterized by some asymmetry that can be perceived with perfect accuracy. Where roles A and B refer to the asymmetry between opponents, ESSs are: [`]fight when A, retreat when B', and vice versa. Either can be an ESS, but only if the [`]reserve strategy' (=what an animal does when it fights) is sufficiently damaging. We examine the [`]war of attrition' (winner = opponent that persists longer). In a population at either ESS, reserve strategy is never normally shown; it is therefore subject to drift unless the selective action of rare individuals which break the convention is considered. These could arise either by mutation or by mistakes in role assessment. When mutations and mistakes simply specify that occasionally an animal fights when it [`]should' retreat, selection adjusts reserve strategy to a level where only one ESS (the [`]commonsense' ESS) is possible, if the asymmetry is relevant to payoff. Thus for asymmetries in fighting ability or resource value, the individual with the lower score will retreat. However, we are particularly concerned with cases where both payoff-relevant aspects (fighting ability and resource value) are asymmetric. If opponents sustain contest costs at rates KA and KB, and their resource values are VA and VB, an [`]optimal assessor' strategy defined by the interaction between the two asymmetries, is a unique ESS. It obeys the rule [`]fight on estimating role A, where VA/KA>VB/KB; retreat in B'. If mistakes can occur in both roles, but are very rate, the ESS is not fundamentally altered though there will be infinitesimal tendencies for persisting in role B. Selection to improve assessment abilities intensifies as abilities improve, but is weak if roles A and B are rather similar. Over a range of similarity between roles, an [`]owner wins' convention may be adopted if ownership correlates positively with role A and an individual cannot tell when it would otherwise pay him to break the convention. We also examine a contest in which information about roles can be acquired only during a contest itself, and at a cost. Much depends on the rate at which information is acquired relative to the rate at which costs are expended, and on whether contests normally escalate in intensity, remain at the same level, or de-escalate. Selection favours short contests when costs are high relative to resource value, where the outcome of a round contains much information about fighting ability, and where the actual disparity in fighting ability is large.  
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  Series Volume Series Issue Edition  
  ISSN 0003-3472 ISBN Medium  
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  Notes Approved no  
  Call Number Equine Behaviour @ team @ Serial 5325  
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Author (up) Smith, J.M.; Parker, G.A. url  doi
openurl 
  Title The logic of asymmetric contests Type Journal Article
  Year 1976 Publication Animal Behaviour. Abbreviated Journal Anim. Behav.  
  Volume 24 Issue 1 Pages 159-175  
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  Abstract A theoretical analysis is made of the evolution of behavioural strategies in contest situations. It is assumed that behaviour will evolve so as to maximize individual fitness. If so, a population will evolve an [`]evolutionarily stable strategy', or ESS, which can be defined as a strategy such that, if all members of a population adopt it, no [`]mutant' strategy can do better. A number of simple models of contest situations are analysed from this point of view. It is concluded that in [`]symmetric' contests the ESS is likely to be a [`]mixed' strategy; that is, either the population will be genetically polymorphic or individuals will be behaviourally variable. Most real contests are probably asymmetric, either in pay-off to the contestants, or in size or weapons, or in some [`]uncorrelated' fashion; i.e. in a fashion which does not substantially bias either the pay-offs or the likely outcome of an escalated contest. An example of an uncorrelated asymmetry is that between the [`]discoverer' of a resource and a [`]late-comer'. It is shown that the ESS in asymmetric contests will usually be to permit the asymmetric cue to settle the contest without escalation. Escalated contests will, however, occur if information to the contestants about the asymmetry is imperfect.  
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  Series Volume Series Issue Edition  
  ISSN 0003-3472 ISBN Medium  
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  Notes Approved no  
  Call Number Equine Behaviour @ team @ Serial 5103  
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