Grafen, A. (1990a). Biological signals as handicaps. Journal of Theoretical Biology, 144, 517-- 546.  Home/Search   Document Not in Database   Summary   Related Articles   Check

.... one maintains that ALife models are thought experiments because they provide insights into possible worlds (life as it could be and maybe is) rather than the actual world, one risks counting many well known mathematical models from, say, theoretical biology (e.g. Grafens handicap principle models [24]) as thought experiments. And that is to lose a distinction (between mathematical models and thought experiments) which is worth having. This loss prevails even if one adds in Dennetts rider about possibility and necessity, or, in the case of simulations, Di Paolo et al..s [21] neo Kuhnian ....

Grafen, A. 1990. Biological signals as handicaps. Journal of Theoretical Biology, 144: 517-546.

....strange behavior of babblers if we introduce the concept of quality: only high quality birds can afford to spend energy in wasteful altruistic acts. Altruism would be a way to advertise one s quality in order to attract mates. Such accounts have been proven sound in the frame of sexual selection (Grafen 1990). We will not consider this explanation, even if it could be relevant to the specific case of babblers, for three reasons. First, Grafen takes for granted the fact that females should prefer high quality males. However, since high quality is balanced by a heavy handicap, for the father as for ....

Grafen, A. (1990). "Biological signals as handicaps". Journal of Theoretical Biology, 144, 517-546.

....at least o ered an explanation, even if it appeared counter intuitive. The second factor in Zahavi s favour was the rise of game theoretic modelling in behavioural ecology (Maynard Smith, 1982) From 1985 onwards, a series of successful, game theoretic models (Enquist, 1985, being the rst, and Grafen, 1990, being the foremost amongst these) demonstrated the soundness of the handicap principle s central tenets, succeeding where population genetic models had previously failed (see Maynard Smith, 1985, for a review) As evolutionary game theory bene ted from its success in dealing with ideas which had ....

....are thus able to signal more Johnstone (1997) has usefully divided handicap models into these two kinds. The rst attempts to account for the evolutionary stability of the honest advertisement of quality as the result of the manner in which the gross costs of signalling vary with quality (e.g. Grafen, 1990; Hurd, 1995) The second kind attempts to account for the evolutionary stability of the honest advertisement of need as the result of the manner in which gross signaller bene ts vary with need (e.g. Godfray, 1991; Maynard Smith, 1991) The latter kind of model includes that used by Godfray ....

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Grafen, A. (1990). Biological signals as handicaps. Journal of Theoretical Biology, 144, 517-546.

....of animal conflicts. It has provided explanations for apparently paradoxical situations, for example the practice of heavily armed animals engaging only in ritualistic contests (Maynard Smith, 1982) and the tendency of (especially male) animals to develop extremely costly signals to acquire mates (Grafen, 1990a; Grafen, 1990b) The concept of an Evolutionarily Stable Strategy (ESS) introduced in Maynard Smith Price (1973) has been especially useful, and has been central to a large body of literature; some important examples being Bishop Cannings (1976) Cressman (1992) Haigh (1975) Hofbauer ....

.... It has provided explanations for apparently paradoxical situations, for example the practice of heavily armed animals engaging only in ritualistic contests (Maynard Smith, 1982) and the tendency of (especially male) animals to develop extremely costly signals to acquire mates (Grafen, 1990a; Grafen, 1990b) The concept of an Evolutionarily Stable Strategy (ESS) introduced in Maynard Smith Price (1973) has been especially useful, and has been central to a large body of literature; some important examples being Bishop Cannings (1976) Cressman (1992) Haigh (1975) Hofbauer Sigmund (1988) ....

GRAFEN, A. (1990b). Biological signals as handicaps. J. theor. Biol. 144, 517-546.

....by theoretical biologists. Population genetic models [5, 6] seemed to show that it could not be evolutionarily stable. However, the potential effectiveness of the handicap principle has been validated by several mathematical models in recent years; foremost among these is a model by Grafen [7]. This model establishes that the handicap principle can work, but specifies an important proviso: the unit cost of producing the signal must be greater for a low quality signaller than for a high quality signaller. In other words, the fitness cost of extending one s tail by an extra centimetre ....

....by tending to have shorter tails as adults. Females preferring to mate with long tailed males will thus mate with higher quality males on average. 2 Modelling Sexual Signalling of Genetic Quality Almost all of the models that have recently demonstrated the plausibility of the handicap principle [7, 9, 10] have made a major simplifying assumption: namely, that the underlying male quality of interest to females is environmentally determined. This could mean, for example, that males are advertising their level of nutrition, or the quality of the territory they possess. This assumption misses the ....

Grafen, A.: Biological signals as handicaps. JTB 144 (1990) 517--546

....signals that will be believed by receivers. When the handicap principle was first introduced, it was generally not accepted by theoretical biologists. Simple population genetic models seemed to show that it could not be evolutionarily stable. However, an elaborate mathematical model developed by Grafen (1990) appears to have vindicated Zahavi s idea and has made the handicap principle a respectable explanatory construct. Simulation models of the evolution of communication have been put forward before, but have rarely considered the general case that is implied by Krebs and Dawkins s theory: the ....

....communication requires, on average, honest signallers and trusting receivers, and thus will only develop when PS 0 and PR 0, i.e. when both participants are selected to participate. However, real animals sometimes communicate despite apparent conflicts of interest (Hinde, 1981) Recent models (Grafen, 1990; Bullock, 1997) have established 4 No sig. II II I Low High I II II Pos. Pos. Pos. Pos. Neg. Neg. Neg. Neg. Sig. No sig. Sig. Figure 2: Extended form of the simple signalling game. The shaded cell in each chart icon indexes the relevant payoff value in Table 1. that, in certain ....

Grafen, A. (1990). Biological signals as handicaps. Journal of Theoretical Biology, 144, 517--546.

....that could lead to honesty in a signalling system is the handicap principle (Zahavi, 1975, 1987) This is the idea that honesty can be maintained if the signals are costly in a particular way. However, the handicap principle has recently received overwhelming theoretical attention (see for example Grafen, 1990; Iwasa, Pomiankowski, Nee, 1991; Hurd, 1995; Bullock, 1997) and will only be treated tangentially here. 1.1 Manipulative and cooperative signalling Krebs and Dawkins (1984) provide another possible answer, and in so doing challenge the default notion that animal communication is about ....

....displays) then reliable communication could evolve and persist over time this is in line with Zahavi s handicap principle. Bullock made the more specific prediction that in order for communication to be stable, the net cost of signalling must be lower for higher quality signallers (see also Grafen, 1990). However, it could be argued that such differential signal costs effectively render honest signalling mutually beneficial. We will return to this notion below. A second goal of the current paper is to position previous SAB AL work in an overarching theoretical context. To this end some general ....

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Grafen, A. (1990). Biological signals as handicaps. Journal of Theoretical Biology, 144, 517--546.

....cost of a real ght can be avoided (Enquist, 1985) Aggressive signals tend to honestly re ect the ghting ability of the signaler. They may be costly to perform, requiring the presence of the trait they indicate to ensure reliability and prevent exploitation by blu ers (Zahavi and Zahavi, 1997, Grafen, 1990, de Bourcier and Wheeler, 1995) Even so, they are less costly than the direct competition they represent. 3.4 Channelling aggression The experiments in this paper investigate the use of aggressive behaviour to improve performance in multirobot systems. Speci cally, we demonstrate a stylized ....

Grafen, A. (1990). Biological signals as handicaps. Journal of Theoretical Biology, 144:517-546.

....derived Evolutionarily Stable Strategies (ESSs) is undertaken. It is discovered that the system is capable of attaining signalling equilibria in addition to those derived via analytic techniques, and that these additional equilibria are consistent with the definition of conventional signalling. Grafen s (1990) proof of Zahavi s handicap principle is generalised in an analogous manner, and it is demonstrated analytically that non handicap signalling equilibria also exist for this continuous model of honest signalling. 1 Introduction In the wake of the fall of group selectionist thought during the ....

....is an honest indicator of underlying need. It cannot be invaded by cheats because to signal more strongly than your need dictates can only result in a response which is not worth enough to compensate the increased production cost. Notice that whilst the former argument (e.g. Enquist, 1985; Grafen, 1990; Hurd, 1995) assumes differential costs (i.e. that signaller quality might, to some extent, affect the cost of signal production) the latter does not, and that whilst the latter argument (e.g. Godfray, 1991) assumes differential benefits (i.e. that signaller quality might, to some extent, ....

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Grafen, A. (1990). Biological signals as handicaps. J. Theor. Biol., 144, 517 -- 546.

....costly (e.g. long, elaborate tails or energetic ritual displays) then reliable communication could evolve and persist over time. Bullock made the more specific prediction that in order for communication to be stable, the net cost of signalling must be lower for higher quality signallers (see also Grafen, 1990). However, it could be argued that such differential signal costs effectively render honest signalling mutually beneficial. We will return to this notion below. One goal of the current paper is to position previous AL work in an overarching theoretical context. To this end some general models of ....

....communication requires, on average, honest signallers and trusting receivers, and thus will only develop when PS 0 and PR 0, i.e. when both agents are selected to participate. However, real animals sometimes communicate despite apparent conflicts of interest (Hinde 1981) Recent models (Grafen 1990; Bullock 1997) have established that, in certain situations where communication would otherwise be unstable, increasing the production costs of the signal can 1 The term agent is used to refer to an entity that may be playing a signalling or a receiving role. II II I Low High I II II Pos. ....

Grafen, A. 1990. Biological signals as handicaps. Journal of Theoretical Biology 144:517--546.

....fairly simple affair. A prospect s fitness depends on the degree to which she can use a suitor s signal to predict his quality. Her fitness is at a maximum when her response matches suitor quality, and is at some lower value otherwise (examples of models conforming to this characterisation include Grafen, 1990; Godfray, 1991) Within this stereotypical model prospects are considered to be passive recipients. This passivity takes three related forms. 1.1 Information gathering vs. Decision making A tacit assumption within the stereotypical model outlined above is that prospects are selected to gain ....

Grafen, A. (1990). Biological signals as handicaps. J. Theor.

....effects, and reciprocal effects, acting in isolation or in concert, are likely to account for the majority of the innate communicative behaviors observed in animal species. Possible additional effects, such as the imposition of honest signaling through costly signals (Zahavi, 1975; Zahavi, 1977; Grafen, 1990), may account for additional data. Natural selection, acting through these mediums, seems well equipped to tune innate systems of communication, and the origin of this innate behavior, when examined carefully, appears relatively unmysterious. Chapter V The evolution of exploitation and ....

Grafen, A. (1990). Biological signals as handicaps. Journal of Theoretical Biology 144, 517--546.

....in the area of animal conflicts. It has provided explanations for apparently paradoxical situations, for example the practice of heavily armed animals engaging only in ritualistic contests [20] and the tendency of (especially male) animals to develop extremely costly signals to acquire mates [13] [14]. The concept of an Evolutionarily Stable Strategy (ESS) introduced by Maynard Smith and Price [21] has been especially useful, and has been central to a large body of literature; some important examples being discussed in [4] 12] 15] 18] 20] Most of this work has concentrated on games ....

Grafen,A(1990) Biological signals as handicaps. J.theor.Biol., 144, 517-546.

.... Signalling Equilibria Seth Bullock Center for Adaptive Behavior and Cognition Max Planck Institute for Human Development Lentzeallee 94, D 14195 Berlin ( Dahlem) GERMANY Tel: 49 (0)30 82406 350 Fax: 49 (0)30 82406 399 EMail: bullock mpib berlin.mpg.de Abstract A particular game theoretic model (Grafen, 1990) of the evolutionary stability of honest signalling, which attempts a formal proof of the validity of Zahavi s (1975, 1977) handicap principle, is generalised and rendered as an evolutionary simulation model. In addition to supporting new theoretical results, this allows the effects of differing ....

.... Honest Signalling Equilibria Seth Bullock Center for Adaptive Behavior and Cognition Max Planck Institute for Human Development Lentzeallee 94, D 14195 Berlin ( Dahlem) Tel: 0049 30 82406 350, Fax: 0049 30 82406 399, Email: bullock mpib berlin.mpg.de Abstract A particular game theoretic model (Grafen, 1990) of the evolutionary stability of honest signalling, which attempts a formal proof of the validity of Zahavi s (1975, 1977) handicap principle, is generalised and rendered as an evolutionary simulation model. In addition to supporting new theoretical results, this allows the effects of differing ....

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Grafen, A. (1990). Biological signals as handicaps. J. Theor.

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Grafen, A. (1990a). Biological signals as handicaps. Journal of Theoretical Biology, 144, 517-- 546.

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Grafen, A. (1990), `Biological signals as handicaps', Journal of Theoretical Biology, 144: 517-546.

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A. Grafen, "Biological signals as handicaps," J. Theor. Biol., Vol. 144, pp 517-546.

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Grafen, A. (1990). Biological signals as handicaps. Journal of Theoretical Biology, 144, 517--546.

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Grafen, A. (1990), `Biological signals as handicaps', Journal of Theoretical Biology, 144: 517-546.

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Nature 352, 328-330. Grafen, A. (1990). Biological signals as handicaps. Journal of Theoretical Biology 144, 517-546.

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