scholarly journals Loser-effect duration evolves independently of fighting ability

2019 ◽  
Vol 286 (1903) ◽  
pp. 20190582 ◽  
Author(s):  
Kensuke Okada ◽  
Yasukazu Okada ◽  
Sasha R. X. Dall ◽  
David J. Hosken
Keyword(s):  
Artificial Selection ◽  
Realized Heritability ◽  
Fighting Ability ◽  
Winner And Loser Effects ◽  
Theoretical Predictions ◽  
Competitive Behaviour ◽  
Effect Duration

Winning or losing contests can impact subsequent competitive behaviour and the duration of these effects can be prolonged. While it is clear effects depend on social and developmental environments, the extent to which they are heritable, and hence evolvable, is less clear and remains untested. Furthermore, theory predicts that winner and loser effects should evolve independently of actual fighting ability, but again tests of this prediction are limited. Here we used artificial selection on replicated beetle populations to show that the duration of loser effects can evolve, with a realized heritability of about 17%. We also find that naive fighting ability does not co-evolve with reductions in the duration of the loser effect. We discuss the implications of these findings and how they corroborate theoretical predictions.

scholarly journals Learning your own strength: winner and loser effects should change with age and experience

2010 ◽  
Vol 277 (1686) ◽  
pp. 1427-1434 ◽  
Author(s):  
Tim W. Fawcett ◽  
Rufus A. Johnstone
Keyword(s):  
Aggressive Behaviour ◽  
Relative Magnitude ◽  
Adaptive Behaviour ◽  
Older Individuals ◽  
Fighting Ability ◽  
Aggressive Encounter ◽  
Winner And Loser Effects ◽  
Clear Winner

Winner and loser effects, in which the outcome of an aggressive encounter influences the tendency to escalate future conflicts, have been documented in many taxa, but we have limited understanding of why they have evolved. One possibility is that individuals use previous victories and defeats to assess their fighting ability relative to others. We explored this idea by modelling a population of strong and weak individuals that do not know their own strength, but keep track of how many fights they have won. Under these conditions, adaptive behaviour generates clear winner and loser effects: individuals who win fights should escalate subsequent conflicts, whereas those who lose should retreat from aggressive opponents. But these effects depend strongly on age and experience. Young, naive individuals should show highly aggressive behaviour and pronounced loser effects. For these inexperienced individuals, fighting is especially profitable because it yields valuable information about their strength. Aggression should then decline as an individual ages and gains experience, with those who lose fights becoming more submissive. Older individuals, who have a better idea of their own strength, should be more strongly influenced by victories than losses. In conclusion, we predict that both aggressiveness and the relative magnitude of winner and loser effects should change with age, owing to changes in how individuals perceive their own strength.

The Evolution of Social Dominance I: Two-player Models

Behaviour ◽  
2003 ◽  
Vol 140 (10) ◽  
pp. 1305-1332 ◽  
Author(s):  
Geerten Hengeveld ◽  
G. Sander Van Doorn ◽  
Franz Weissing
Keyword(s):  
Dominance Rank ◽  
Extreme Case ◽  
Point Of View ◽  
Resource Holding Potential ◽  
Evolutionarily Stable Strategies ◽  
Fighting Ability ◽  
Dominance Relations ◽  
Winner And Loser Effects ◽  
Evolutionarily Stable ◽  
Do So

AbstractA difference in dominance rank is an often-used cue to resolve conflicts between two animals without escalated fights. At the group level, adherence to a dominance convention efficiently reduces the costs associated with conflicts, but from an individual's point of view, it is difficult to explain why a low ranking individual should accept its subordinate status. This is especially true if, as suggested by several authors, dominance not necessarily reflects differences in fighting ability but rather results from arbitrary historical asymmetries. According to this idea, rank differentiation emerges from behavioural strategies, referred to as winner and loser effects, in which winners of previous conflicts are more likely to win the current conflict, whereas the losers of previous conflicts are less likely to do so. In order to investigate whether dominance, based on such winner and loser effects, can be evolutionarily stable, we analyse a game theoretical model. The model focuses on an extreme case in which there are no differences in fighting ability between individuals at all. The only asymmetries that may arise between individuals are generated by the outcome of previous conflicts. By means of numerical analysis, we find alternative evolutionarily stable strategies, which all utilize these asymmetries for conventional conflict resolution. One class of these strategies is based on winner and loser effects, thus generating evolutionarily stable dominance relations even in the absence of differences in resource holding potential.

The Evolution of Social Dominance II: Multi-Player Models

Behaviour ◽  
2003 ◽  
Vol 140 (10) ◽  
pp. 1333-1358 ◽  
Author(s):  
G. Sander Van Doorn ◽  
Franz Weissing ◽  
Geerten Hengeveld
Keyword(s):  
Extreme Case ◽  
Evolutionarily Stable Strategies ◽  
Social Hierarchies ◽  
Natural Systems ◽  
Fighting Ability ◽  
Winner And Loser Effects ◽  
History Of ◽  
Linear Hierarchies ◽  
High Degree ◽  
Evolutionarily Stable

AbstractThe social hierarchies observed in natural systems often show a high degree of transitivity. Transitive hierarchies do not only require rank differentiation within pairs of individuals but also a higher level ordering of relations within the group. Several authors have suggested that the formation of linear hierarchies at the group level is an emergent property of individual behavioural rules, referred to as winner and loser effects. Winner and loser effects occur if winners of previous conflicts are more likely to escalate the current conflict, whereas the losers of previous conflicts are less likely to do so. According to this idea, an individual's position in a hierarchy may not necessarily reflect its fighting ability, but may rather result from arbitrary historical asymmetries, in particular the history of victories and defeats. However, if this is the case, it is difficult to explain from an evolutionary perspective why a low ranking individual should accept its subordinate status. Here we present a game theoretical model to investigate whether winner and loser effects giving rise to transitive hierarchies can evolve and under which conditions they are evolutionarily stable. The main version of the model focuses on an extreme case in which there are no intrinsic differences in fighting ability between individuals. The only asymmetries that may arise between individuals are generated by the outcome of previous conflicts. We show that, at evolutionary equilibrium, these asymmetries can be utilized for conventional conflict resolution. Several evolutionarily stable strategies are based on winner and loser effects and these strategies give rise to transitive hierarchies.

Artificial Selection on Growth and Correlated Selection on Competitive Behaviour in Fish

1986 ◽  
Vol 43 (5) ◽  
pp. 1059-1064 ◽  
Author(s):  
Roger W. Doyle ◽  
André J. Talbot
Keyword(s):  
Growth Rate ◽  
Artificial Selection ◽  
Rapid Growth ◽  
Relative Size ◽  
Genetic Stock ◽  
Competitive Behaviour ◽  
Game Theoretic ◽  
Improvement Programs ◽  
Selection For ◽  
Rate Selection

There is widespread concern that artificial selection for rapid growth will indirectly select for aggressive fish, thus nullifying genetic stock improvement programs based on selection. We show that this unfortunate result is highly unlikely. The argument is based on a game-theoretic analysis of two general features of fish competition: (1) the growth of some individuals is often suppressed even when food is abundant and (2) the behaviour of a fish towards other members of a population depends on its relative size. The commonsense view that growth rate selection favours aggressive fish is shown to be correct only when aggressive behaviour is independent of relative size and resources are severely limited. In experimental and aquaculture environments, growth rate selection is shown to favour a decrease in the value of both aggressive and submissive behaviour, i.e. fish which ignore each other. Artificial selection for rapid growth will therefore indirectly select for tameness, not aggression.

Microcalorimeters for X-Ray Spectroscopy

1988 ◽  
Vol 102 ◽  
pp. 41
Author(s):  
E. Silver ◽  
C. Hailey ◽  
S. Labov ◽  
N. Madden ◽  
D. Landis ◽  
...  
Keyword(s):  
High Resolution ◽  
High Efficiency ◽  
Thermal Response ◽  
Low Noise ◽  
High Resolution Spectroscopy ◽  
Superconducting Transition ◽  
Sapphire Substrates ◽  
Laboratory Plasmas ◽  
Adiabatic Demagnetization ◽  
Theoretical Predictions

The merits of microcalorimetry below 1°K for high resolution spectroscopy has become widely recognized on theoretical grounds. By combining the high efficiency, broadband spectral sensitivity of traditional photoelectric detectors with the high resolution capabilities characteristic of dispersive spectrometers, the microcalorimeter could potentially revolutionize spectroscopic measurements of astrophysical and laboratory plasmas. In actuality, however, the performance of prototype instruments has fallen short of theoretical predictions and practical detectors are still unavailable for use as laboratory and space-based instruments. These issues are currently being addressed by the new collaborative initiative between LLNL, LBL, U.C.I., U.C.B., and U.C.D.. Microcalorimeters of various types are being developed and tested at temperatures of 1.4, 0.3, and 0.1°K. These include monolithic devices made from NTD Germanium and composite configurations using sapphire substrates with temperature sensors fabricated from NTD Germanium, evaporative films of Germanium-Gold alloy, or material with superconducting transition edges. A new approache to low noise pulse counting electronics has been developed that allows the ultimate speed of the device to be determined solely by the detector thermal response and geometry. Our laboratory studies of the thermal and resistive properties of these and other candidate materials should enable us to characterize the pulse shape and subsequently predict the ultimate performance. We are building a compact adiabatic demagnetization refrigerator for conveniently reaching 0.1°K in the laboratory and for use in future satellite-borne missions. A description of this instrument together with results from our most recent experiments will be presented.

A crystallographic analysis of the CoSi/Si(111) interface using Transmission Electron Microscopy

1990 ◽  
Vol 48 (4) ◽  
pp. 574-575
Author(s):  
A.C. Daykin ◽  
C.J. Kiely ◽  
R.C. Pond ◽  
J.L. Batstone
Keyword(s):  
Electron Microscopy ◽  
Transmission Electron Microscopy ◽  
Defect Structure ◽  
Room Temperature ◽  
Theoretical Method ◽  
Crystallographic Analysis ◽  
Si Substrate ◽  
Transmission Electron ◽  
Theoretical Predictions

When CoSi2 is grown onto a Si(111) surface it can form in two distinct orientations. A-type CoSi2 has the same orientation as the Si substrate and B-type is rotated by 180° degrees about the [111] surface normal.One method of producing epitaxial CoSi2 is to deposit Co at room temperature and anneal to 650°C.If greater than 10Å of Co is deposited then both A and B-type CoSi2 form via a number of intermediate silicides .The literature suggests that the co-existence of A and B-type CoSi2 is in some way linked to these intermediate silicides analogous to the NiSi2/Si(111) system. The phase which forms prior to complete CoSi2 formation is CoSi. This paper is a crystallographic analysis of the CoSi2/Si(l11) bicrystal using a theoretical method developed by Pond. Transmission electron microscopy (TEM) has been used to verify the theoretical predictions and to characterise the defect structure at the interface.

Combining Defaults and Transparency Information to Increase Policy Compliance

2020 ◽  
Vol 51 (5) ◽  
pp. 354-359 ◽  
Author(s):  
Yavor Paunov ◽  
Michaela Wänke ◽  
Tobias Vogel
Keyword(s):  
Independent Effect ◽  
Online Experiment ◽  
Policy Compliance ◽  
Empirical Question ◽  
Theoretical Predictions

Abstract. Combining the strengths of defaults and transparency information is a potentially powerful way to induce policy compliance. Despite negative theoretical predictions, a recent line of research revealed that default nudges may become more effective if people are informed why they should exhibit the targeted behavior. Yet, it is an open empirical question whether the increase in compliance came from setting a default and consequently disclosing it, or the provided information was sufficient to deliver the effect on its own. Results from an online experiment indicate that both defaulting and transparency information exert a statistically independent effect on compliance, with highest compliance rates observed in the combined condition. Practical and theoretical implications are discussed.

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