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	Author	Brilot, B.O.; Johnstone, R.A.
	Title	The limits to cost-free signalling of need between relatives			Type	Journal Article
	Year	2003	Publication	Proceedings. Biological sciences / The Royal Society	Abbreviated Journal	Proc Biol Sci
	Volume	270	Issue	1519	Pages	1055-1060
	Keywords	Animal Communication; Animals; Birds/physiology; Models, Biological; Social Behavior
	Abstract	Theoretical models have demonstrated the possibility of stable cost-free signalling of need between relatives. The stability of these cost-free equilibria depends on the indirect fitness cost of cheating and deceiving a donor into giving away resources. We show that this stability is highly sensitive to the distribution of need among signallers and receivers. In particular, cost-free signalling is likely to prove stable only if there is very large variation in need (such that the least-needy individuals stand to gain much less than the most-needy individuals from additional resources). We discuss whether these conditions are likely to be found in altricial avian breeding systems--the most intensively studied instance of signalling of need between relatives. We suggest that cost-free signalling is more likely to prove stable and will provide parents with more information during the earlier phases of chick growth, when parents can more easily meet the demands of a brood (and chicks are more likely to reach satiation). Later, informative yet cost-free signalling is unlikely to persist.
	Address	Department of Zoology, University of Cambridge, Downing Street, Cambridge CB2 3EJ, UK. bob21@cam.ac.uk
	Corporate Author				Thesis
	Publisher		Place of Publication		Editor
	Language	English	Summary Language		Original Title
	Series Editor		Series Title		Abbreviated Series Title
	Series Volume		Series Issue		Edition
	ISSN	0962-8452	ISBN		Medium
	Area		Expedition		Conference
	Notes	PMID:12803895			Approved	no
	Call Number	refbase @ user @			Serial	558
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	Author	Wilson, D.A.; Stevenson, R.J.
	Title	The fundamental role of memory in olfactory perception			Type	Journal Article
	Year	2003	Publication	Trends in Neurosciences	Abbreviated Journal	Trends. Neurosci.
	Volume	26	Issue	5	Pages	243-247
	Keywords	olfactory perception mammals
	Abstract	Current emphasis on odorant physiochemical features as the basis for perception largely ignores the synthetic and experience-dependent nature of olfaction. Olfaction is synthetic, as mammals have only limited ability to identify elements within even simple odor mixtures. Furthermore, olfaction is experience-bound, as exposure alone can significantly affect the extent to which stimuli can be discriminated. We propose that early analytical processing of odors is inaccessible at the behavioral level and that all odors are initially encoded as `objects' in the piriform cortex. Moreover, we suggest that odor perception is wholly dependent on the integrity of this memory system and that its loss severely impairs normal perception.
	Address
	Corporate Author				Thesis
	Publisher		Place of Publication		Editor
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	Series Volume		Series Issue		Edition
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	Area		Expedition		Conference
	Notes				Approved	no
	Call Number	refbase @ user @			Serial	795
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	Author	Dubois, F.; Giraldeau, L.-A.
	Title	The forager's dilemma: food sharing and food defense as risk-sensitive foraging options			Type	Journal Article
	Year	2003	Publication	The American Naturalist	Abbreviated Journal	Am Nat
	Volume	162	Issue	6	Pages	768-779
	Keywords	Animals; Competitive Behavior/physiology; Environment; Feeding Behavior/physiology; Game Theory; *Models, Biological; Population Density; Population Dynamics
	Abstract	Although many variants of the hawk-dove game predict the frequency at which group foraging animals should compete aggressively, none of them can explain why a large number of group foraging animals share food clumps without any overt aggression. One reason for this shortcoming is that hawk-dove games typically consider only a single contest, while most group foraging situations involve opponents that interact repeatedly over discovered food clumps. The present iterated hawk-dove game predicts that in situations that are analogous to a prisoner's dilemma, animals should share the resources without aggression, provided that the number of simultaneously available food clumps is sufficiently large and the number of competitors is relatively small. However, given that the expected gain of an aggressive animal is more variable than the gain expected by nonaggressive individuals, the predicted effect of the number of food items in a clump-clump richness-depends on whether only the mean or both the mean and variability associated with payoffs are considered. More precisely, the deterministic game predicts that aggression should increase with clump richness, whereas the stochastic risk-sensitive game predicts that the frequency of encounters resulting in aggression should peak at intermediate clump richnesses or decrease with increasing clump richness if animals show sensitivity to the variance or coefficient of variation, respectively.
	Address	Departement des Sciences Biologiques, Universite du Quebec a Montreal, Case postale 8888, Succursale Centre-Ville, Montreal, Quebec H3C 3P8, Canada. fdubois@u-bourgogne.fr
	Corporate Author				Thesis
	Publisher		Place of Publication		Editor
	Language	English	Summary Language		Original Title
	Series Editor		Series Title		Abbreviated Series Title
	Series Volume		Series Issue		Edition
	ISSN	0003-0147	ISBN		Medium
	Area		Expedition		Conference
	Notes	PMID:14737714			Approved	no
	Call Number				Serial	2132
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	Author	Van Doorn G.S.; Hengeveld G.M.; Weissing F.J.
	Title	The Evolution of Social Dominance II: Multi-Player Models			Type	Journal Article
	Year	2003	Publication	Behavior	Abbreviated Journal	Behavior
	Volume	140	Issue	10	Pages	1333-1358
	Keywords
	Abstract	The 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.
	Address
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	Notes				Approved	no
	Call Number	Equine Behaviour @ team @			Serial	5106
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	Author	Van Doorn G.S.; Hengeveld G.M.; Weissing F.J.
	Title	The Evolution of Social Dominance I: Two-player Models			Type	Journal Article
	Year	2003	Publication	Behavior	Abbreviated Journal	Behavior
	Volume	140	Issue	10	Pages	1305-1332
	Keywords
	Abstract	A 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.
	Address
	Corporate Author				Thesis
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	Language		Summary Language		Original Title
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	Notes				Approved	no
	Call Number	Equine Behaviour @ team @			Serial	5105
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	Author	Dugatkin, L.A.; Perlin, M.; Atlas, R.
	Title	The Evolution of Group-beneficial Traits in the Absence of Between-group Selection			Type	Journal Article
	Year	2003	Publication	Journal of Theoretical Biology	Abbreviated Journal	J. Theor. Biol.
	Volume	220	Issue	1	Pages	67-74
	Keywords
	Abstract	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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	Corporate Author				Thesis
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	Notes				Approved	no
	Call Number	refbase @ user @			Serial	491
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	Author	McDonnell, S.M. (ed)
	Title	The Equid Ethogram: A Practical Field Guide to Horse Behavior			Type	Book Whole
	Year	2003	Publication		Abbreviated Journal
	Volume		Issue		Pages
	Keywords
	Abstract
	Address
	Corporate Author				Thesis
	Publisher	Eclipse Press	Place of Publication	Lexington, Kentucky	Editor	McDonnell, S.M.
	Language		Summary Language		Original Title
	Series Editor		Series Title		Abbreviated Series Title
	Series Volume		Series Issue		Edition
	ISSN		ISBN	978-1581500905	Medium
	Area		Expedition		Conference
	Notes				Approved	no
	Call Number	refbase @ user @			Serial	711
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	Author	McKinley, S.; Young, R.J.
	Title	The efficacy of the model-rival method when compared with operant conditioning for training domestic dogs to perform a retrieval-selection task			Type	Journal Article
	Year	2003	Publication	Applied Animal Behaviour Science	Abbreviated Journal	Appl. Anim. Behav. Sci.
	Volume	81	Issue	4	Pages	357-365
	Keywords	Dogs; Learning; Operant conditioning; Model-rival; Cognition
	Abstract	Traditionally, dogs have been trained by operant conditioning techniques; that is, dogs make a desired behavioural response and this response is reinforced by a reward such as food. This type of training is very effective in training dogs to perform basic obedience behaviours (e.g. `stay'). However, dogs are social animals and should be predisposed to learn from social stimuli. In the present study, we used a modified version of the model-rival technique that has been extensively used in experiments investigating the cognitive ability of parrots. In this technique, social stimuli are used to create in the animal an interest in the object without the use of food or other rewards. Therefore, the animal learns the name of the object (intrinsic reward) and not that the object's name means food. In this experiment we compared the learning ability of nine pet dogs to solve the same retrieval-selection task having been previously trained using operant conditioning or model-rival techniques. The retrieval-selection task was the dogs had to correctly select the commanded object to bring to the experimenter from a group of three similar objects. The results show no difference in the speeds with which the dogs solved the test--demonstrating the efficacy of the model-rival method. This is the first time that the effectiveness of the model-rival technique has been experimentally demonstrated with dogs. Furthermore, we believe that the methodology reported in this paper has applications in dog training and in experiments into dog cognition.
	Address
	Corporate Author				Thesis
	Publisher		Place of Publication		Editor
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	Notes				Approved	no
	Call Number	Equine Behaviour @ team @			Serial	2900
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	Author	Golland, L.C.; Evans, D.L.; McGowan, C.M.; Hodgson, D.R.; Rose, R.J.
	Title	The effects of overtraining on blood volumes in standardbred racehorses			Type	Journal Article
	Year	2003	Publication	Veterinary Journal (London, England : 1997)	Abbreviated Journal	Vet J
	Volume	165	Issue	3	Pages	228-233
	Keywords	Animals; Blood Volume; Erythrocytes/physiology; Hematocrit/veterinary; Horse Diseases/etiology/physiopathology; Horses; Male; Physical Conditioning, Animal; Physical Endurance
	Abstract	Red blood cell hypervolaemia has been used for diagnosis of overtraining in racehorses, and has been suggested as a mechanism of this cause of loss of racing performance. The effects of overload training (OLT) on the plasma, blood and red cell volumes were investigated in a prospective study in 12 Standardbred horses. Measurements of blood volumes were made after eight and 32 weeks of an exercise training study. Horses were randomly allocated to OLT and control groups (n=6) after 16 weeks of training. Training duration and intensity were increased more rapidly for the OLT group from week 16, until overtraining was diagnosed in week 32.There were no significant effects of OLT on plasma, blood or total red cell volumes between weeks eight and 32. These volumes significantly decreased with time. Maximal haematocrit after exercise was lower (P<0.05) in the OT group in week 32 (0.57+/-0.003% L/L) than in week eight (0.59+/-0.004 L/L). It was concluded that red cell hypervolaemia was not a mechanism for the decrease in capacity for exercise that occurs with overtraining.
	Address	Faculty of Veterinary Science, University of Sydney, Sydney, NSW 2006, Australia
	Corporate Author				Thesis
	Publisher		Place of Publication		Editor
	Language	English	Summary Language		Original Title
	Series Editor		Series Title		Abbreviated Series Title
	Series Volume		Series Issue		Edition
	ISSN	1090-0233	ISBN		Medium
	Area		Expedition		Conference
	Notes	PMID:12672368			Approved	no
	Call Number	Equine Behaviour @ team @			Serial	4045
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	Author	Hall, C.A.; Cassaday, H.J.; Derrington, A.M.
	Title	The effect of stimulus height on visual discrimination in horses			Type	Journal Article
	Year	2003	Publication	Journal of Animal Science	Abbreviated Journal	J. Anim Sci.
	Volume	81	Issue	7	Pages	1715-1720
	Keywords	Animals; Discrimination Learning/physiology; Female; Horses/physiology/psychology; Male; Orientation; Photic Stimulation; Vision/physiology
	Abstract	This study investigated the effect of stimulus height on the ability of horses to learn a simple visual discrimination task. Eight horses were trained to perform a two-choice, black/white discrimination with stimuli presented at one of two heights: ground level or at a height of 70 cm from the ground. The height at which the stimuli were presented was alternated from one session to the next. All trials within a single session were presented at the same height. The criterion for learning was four consecutive sessions of 70% correct responses. Performance was found to be better when stimuli were presented at ground level with respect to the number of trials taken to reach the criterion (P < 0.05), percentage of correct first choices (P < 0.01), and repeated errors made (P < 0.01). Thus, training horses to carry out tasks of visual discrimination could be enhanced by placing the stimuli on the ground. In addition, the results of the present study suggest that the visual appearance of ground surfaces is an important factor in both horse management and training.
	Address	School of Land-based Studies, Nottingham Trent University, Brackenhurst College Campus, Southwell, Nottinghamshire, England NG25 0QF. carol.hall@ntu.ac.uk
	Corporate Author				Thesis
	Publisher		Place of Publication		Editor
	Language	English	Summary Language		Original Title
	Series Editor		Series Title		Abbreviated Series Title
	Series Volume		Series Issue		Edition
	ISSN	0021-8812	ISBN		Medium
	Area		Expedition		Conference
	Notes	PMID:12854807			Approved	no
	Call Number	refbase @ user @			Serial	835
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