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	Author	Cameron, E.Z.; du Toit, J.T.
	Title	Winning by a neck: tall giraffes avoid competing with shorter browsers			Type	Journal Article
	Year	2007	Publication	The American naturalist	Abbreviated Journal	Am Nat
	Volume	169	Issue	1	Pages	130-135
	Keywords	Acacia/growth & development; Animals; Feeding Behavior/physiology; Neck/anatomy & histology; Plant Leaves/growth & development; Ruminants/anatomy & histology/physiology; South Africa
	Abstract	With their vertically elongated body form, giraffes generally feed above the level of other browsers within the savanna browsing guild, despite having access to foliage at lower levels. They ingest more leaf mass per bite when foraging high in the tree, perhaps because smaller, more selective browsers deplete shoots at lower levels or because trees differentially allocate resources to promote shoot growth in the upper canopy. We erected exclosures around individual Acacia nigrescens trees in the greater Kruger ecosystem, South Africa. After a complete growing season, we found no differences in leaf biomass per shoot across height zones in excluded trees but significant differences in control trees. We conclude that giraffes preferentially browse at high levels in the canopy to avoid competition with smaller browsers. Our findings are analogous with those from studies of grazing guilds and demonstrate that resource partitioning can be driven by competition when smaller foragers displace larger foragers from shared resources. This provides the first experimental support for the classic evolutionary hypothesis that vertical elongation of the giraffe body is an outcome of competition within the browsing ungulate guild.
	Address	Mammal Research Institute, Department of Zoology and Entomology, University of Pretoria, Pretoria 0002, South Africa. ezcameron@zoology.up.ac.za
	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	1537-5323	ISBN		Medium
	Area		Expedition		Conference
	Notes	PMID:17206591			Approved	no
	Call Number	refbase @ user @			Serial	410
Permanent link to this record



	Author	Cameron, E.Z.
	Title	Facultative adjustment of mammalian sex ratios in support of the Trivers-Willard hypothesis: evidence for a mechanism			Type	Journal Article
	Year	2004	Publication	Proceedings. Biological sciences / The Royal Society	Abbreviated Journal	Proc Biol Sci
	Volume	271	Issue	1549	Pages	1723-1728
	Keywords	Age Factors; Animals; Body Constitution; Evolution; Female; Glucose/metabolism/physiology; Litter Size; Male; Mammals/physiology; Models, Biological; Reproduction/physiology; Seasons; Sex Factors; Sex Ratio; Time Factors
	Abstract	Evolutionary theory predicts that mothers of different condition should adjust the birth sex ratio of their offspring in relation to future reproductive benefits. Published studies addressing variation in mammalian sex ratios have produced surprisingly contradictory results. Explaining the source of such variation has been a challenge for sex-ratio theory, not least because no mechanism for sex-ratio adjustment is known. I conducted a meta-analysis of previous mammalian sex-ratio studies to determine if there are any overall patterns in sex-ratio variation. The contradictory nature of previous results was confirmed. However, studies that investigated indices of condition around conception show almost unanimous support for the prediction that mothers in good condition bias their litters towards sons. Recent research on the role of glucose in reproductive functioning have shown that excess glucose favours the development of male blastocysts, providing a potential mechanism for sex-ratio variation in relation to maternal condition around conception. Furthermore, many of the conflicting results from studies on sex-ratio adjustment would be explained if glucose levels in utero during early cell division contributed to the determination of offspring sex ratios.
	Address	Mammal Research Institute, Department of Zoology and Entomology, University of Pretoria, Pretoria 0002, South Africa. ezcameron@zoology.up.ac.za
	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:15306293			Approved	no
	Call Number	refbase @ user @			Serial	413
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	Author	Huebener, E.
	Title	The Rider's Impacts and Their Timers – Example: Rider's Aids for Transitions Between Different Gaits.			Type	Journal Article
	Year	2006	Publication	Tierärztliche Umschau	Abbreviated Journal	Tierärztl. Umschau
	Volume	10	Issue		Pages	515-532
	Keywords	Animal-friendly rider-horse communication – signals for changing the footfall – knee-jerk impacts in the single “fitting” moment – singular timer for those – immediate “obedience”
	Abstract	The scientific investigation of the basics of the inherited riding teachings assists in conserving its values. Riding instructors should be able to teach not only “how” but also “why”. The classic European riding teachings that have developed across the centuries are based on perceptions that have their roots in natural phenomena. They are being mirrored, for instance, in the aids to stimulate the change from one gait to the next. The movements of the horse's trunk and back provide timers for horse-friendly, sensitive aids that create attentive, diligent and happily cooperating horses.
	Address
	Corporate Author				Thesis
	Publisher		Place of Publication		Editor
	Language	German	Summary Language		Original Title
	Series Editor		Series Title		Abbreviated Series Title
	Series Volume		Series Issue		Edition
	ISSN		ISBN		Medium
	Area		Expedition		Conference
	Notes				Approved	yes
	Call Number	refbase @ user @			Serial	434
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	Author	Broom, M.
	Title	A unified model of dominance hierarchy formation and maintenance			Type	Journal Article
	Year	2002	Publication	Journal of theoretical biology	Abbreviated Journal	J. Theor. Biol.
	Volume	219	Issue	1	Pages	63-72
	Keywords	Animals; Behavior, Animal; Feeding Behavior; Models, Psychological; *Social Dominance; Social Environment
	Abstract	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.
	Address	Centre for Statistics and Stochastic Modelling, School of Mathematical Sciences, University of Sussex, Falmer, Brighton, BN1 9QH, U.K. m.broom@sussex.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	0022-5193	ISBN		Medium
	Area		Expedition		Conference
	Notes	PMID:12392975			Approved	no
	Call Number	refbase @ user @			Serial	439
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	Author	Chase, I.D.; Tovey, C.; Spangler-Martin, D.; Manfredonia, M.
	Title	Individual differences versus social dynamics in the formation of animal dominance hierarchies			Type	Journal Article
	Year	2002	Publication	Proceedings of the National Academy of Sciences of the United States of America	Abbreviated Journal	Proc. Natl. Acad. Sci. U.S.A.
	Volume	99	Issue	8	Pages	5744-5749
	Keywords	Animals; Behavior, Animal; Fishes; Humans; Social Behavior; *Social Dominance
	Abstract	Linear hierarchies, the classical pecking-order structures, are formed readily in both nature and the laboratory in a great range of species including humans. However, the probability of getting linear structures by chance alone is quite low. In this paper we investigate the two hypotheses that are proposed most often to explain linear hierarchies: they are predetermined by differences in the attributes of animals, or they are produced by the dynamics of social interaction, i.e., they are self-organizing. We evaluate these hypotheses using cichlid fish as model animals, and although differences in attributes play a significant part, we find that social interaction is necessary for high proportions of groups with linear hierarchies. Our results suggest that dominance hierarchy formation is a much richer and more complex phenomenon than previously thought, and we explore the implications of these results for evolutionary biology, the social sciences, and the use of animal models in understanding human social organization.
	Address	Department of Sociology, State University of New York, Stony Brook, NY 11794-4356, USA. Ichase@notes.cc.sunysb.edu
	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	0027-8424	ISBN		Medium
	Area		Expedition		Conference
	Notes	PMID:11960030			Approved	no
	Call Number	refbase @ user @			Serial	442
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	Author	Hemelrijk, C.K.; Wantia, J.
	Title	Individual variation by self-organisation			Type	Journal Article
	Year	2005	Publication	Neuroscience and biobehavioral reviews	Abbreviated Journal	Neurosci Biobehav Rev
	Volume	29	Issue	1	Pages	125-136
	Keywords	Aggression; Animals; Behavior, Animal/physiology; Competitive Behavior/physiology; Female; Humans; Individuality; Male; Models, Psychological; Sex Characteristics; Social Dominance; Time Factors
	Abstract	In this paper, we show that differences in dominance and spatial centrality of individuals in a group may arise through self-organisation. Our instrument is a model, called DomWorld, that represents two traits that are often found in animals, namely grouping and competing. In this model individual differences grow under the following conditions: (1) when the intensity of aggression increases and grouping becomes denser, (2) when the degree of sexual dimorphism in fighting power increases. In this case the differences among females compared to males grow too, (3) when, upon encountering another individual, the tendency to attack is 'obligate' and not conditional, namely 'sensitive to risks'. Results resemble phenomena described for societies of primates, mice, birds and pigs.
	Address	Theoretical Biology, University of Groningen, NN Haren, The Netherlands. hemelrij@ifi.unizh.ch
	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	0149-7634	ISBN		Medium
	Area		Expedition		Conference
	Notes	PMID:15652260			Approved	no
	Call Number	refbase @ user @			Serial	443
Permanent link to this record



	Author	Miller, G.
	Title	Animal behavior. Signs of empathy seen in mice			Type	Journal Article
	Year	2006	Publication	Science (New York, N.Y.)	Abbreviated Journal	Science
	Volume	312	Issue	5782	Pages	1860-1861
	Keywords	Altruism; Animals; Behavior, Animal; Empathy; Formaldehyde/administration & dosage; Mice/psychology; Motivation; Pain/psychology; Social Behavior
	Abstract
	Address
	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	1095-9203	ISBN		Medium
	Area		Expedition		Conference
	Notes	PMID:16809499			Approved	no
	Call Number	refbase @ user @			Serial	461
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	Author	Miklósi, Á.; Soproni, K.
	Title	A comparative analysis of animals' understanding of the human pointing gesture			Type	Journal Article
	Year	2006	Publication	Animal cognition	Abbreviated Journal	Anim. Cogn.
	Volume	9	Issue	2	Pages	81-93
	Keywords	Animal Communication; Animals; Behavior, Animal; Child; Child, Preschool; Dogs; Fixation, Ocular; Gestures; Hand; Humans; Nonverbal Communication; Pinnipedia; Primates; Problem Solving; *Recognition (Psychology); Species Specificity
	Abstract	We review studies demonstrating the ability of some animals to understand the human pointing gesture. We present a 3-step analysis of the topic. (1) We compare and evaluate current experimental methods (2) We compare available experimental results on performance of different species and investigate the interaction of species differences and other independent variables (3) We evaluate how our present understanding of pointing comprehension answers questions about function, evolution and mechanisms. Recently, a number of different hypotheses have been put forward to account for the presence of this ability in some species and for the lack of such comprehension in others. In our view, there is no convincing evidence for the assumption that the competitive lifestyles of apes would inhibit the utilization of this human gesture. Similarly, domestication as a special evolutionary factor in the case of some species falls short in explaining high levels of pointing comprehension in some non-domestic species. We also disagree with the simplistic view of describing the phenomenon as a simple form of conditioning. We suggest that a more systematic comparative research is needed to understand the emerging communicative representational abilities in animals that provide the background for comprehending the human pointing gesture.
	Address	Department of Ethology, Eotvos Lorand University, Budapest, Pazmany P 1/c, H-1117, Budapest, Hungary. miklosa@ludens.elte.hu
	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	1435-9448	ISBN		Medium
	Area		Expedition		Conference
	Notes	PMID:16235075			Approved	no
	Call Number	refbase @ user @			Serial	463
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	Author	Mulcahy, N.J.; Call, J.
	Title	Apes save tools for future use			Type	Journal Article
	Year	2006	Publication	Science (New York, N.Y.)	Abbreviated Journal	Science
	Volume	312	Issue	5776	Pages	1038-1040
	Keywords	Animals; Association Learning; Cognition; Evolution; Mental Processes; Pan paniscus; Pan troglodytes; *Pongo pygmaeus
	Abstract	Planning for future needs, not just current ones, is one of the most formidable human cognitive achievements. Whether this skill is a uniquely human adaptation is a controversial issue. In a study we conducted, bonobos and orangutans selected, transported, and saved appropriate tools above baseline levels to use them 1 hour later (experiment 1). Experiment 2 extended these results to a 14-hour delay between collecting and using the tools. Experiment 3 showed that seeing the apparatus during tool selection was not necessary to succeed. These findings suggest that the precursor skills for planning for the future evolved in great apes before 14 million years ago, when all extant great ape species shared a common ancestor.
	Address	Max Planck Institute for Evolutionary Anthropology, Deutscher Platz 6, D-04103 Leipzig, Germany
	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	1095-9203	ISBN		Medium
	Area		Expedition		Conference
	Notes	PMID:16709782			Approved	no
	Call Number	refbase @ user @			Serial	466
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	Author	Johnstone, R.A.
	Title	Eavesdropping and animal conflict			Type	Journal Article
	Year	2001	Publication	Proceedings of the National Academy of Sciences of the United States of America	Abbreviated Journal	Proc. Natl. Acad. Sci. U.S.A.
	Volume	98	Issue	16	Pages	9177-9180
	Keywords	Aggression; Animals; Behavior, Animal; *Conflict (Psychology); Models, Theoretical
	Abstract	Fights between pairs of animals frequently take place within a wider social context. The displays exchanged during conflict, and the outcome of an encounter, are often detectable by individuals who are not immediately involved. In at least some species, such bystanders are known to eavesdrop on contests between others, and to modify their behavior toward the contestants in response to the observed interaction. Here, I extend Maynard Smith's well known model of animal aggression, the Hawk-Dove game, to incorporate the possibility of eavesdroppers. I show that some eavesdropping is favored whenever the cost of losing an escalated fight exceeds the value of the contested resource, and that its equilibrium frequency is greatest when costs are relatively high. Eavesdropping reduces the risk of escalated conflict relative to that expected by chance, given the level of aggression in the population. However, it also promotes increased aggression, because it enhances the value of victory. The net result is that escalated conflicts are predicted to occur more frequently when eavesdropping is possible.
	Address	Department of Zoology, University of Cambridge, Downing Street, Cambridge CB2 3EJ, United Kingdom. raj1003@hermes.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	0027-8424	ISBN		Medium
	Area		Expedition		Conference
	Notes	PMID:11459936			Approved	no
	Call Number	refbase @ user @			Serial	497
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