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	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
Permanent link to this record



	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
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	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	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
Permanent link to this record



	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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	Author	Earley, R.L.; Dugatkin, L.A.
	Title	Eavesdropping on visual cues in green swordtail (Xiphophorus helleri) fights: a case for networking			Type	Journal Article
	Year	2002	Publication	Proceedings. Biological sciences / The Royal Society	Abbreviated Journal	Proc Biol Sci
	Volume	269	Issue	1494	Pages	943-952
	Keywords	Aggression; Animals; Behavior, Animal; *Cyprinodontiformes; Female; Male
	Abstract	Aggressive contests probably occur in networking environments where information about fighting ability is conveyed both to an opponent and to individuals peripheral to the fight itself, the bystanders. Our primary aim was to investigate the relative influences of eavesdropping and prior social experience on the dynamics of aggressive contests in Xiphophorus helleri. A bystander's ability to witness an encounter was manipulated using clear, one-way mirror, and opaque partitions. After watching (or not watching) the initial contest, the bystander encountered either the winner or loser of the bout. Treatment comparisons of bystander-winner or bystander-loser contest dynamics indicated the presence or absence of winner, loser, or eavesdropping effects. Winner and loser effects had negligible influences on bystander contest dynamics. Eavesdropping significantly reduced the bystander's propensity to initiate aggression, escalate, and win against seen winners regardless of whether the watched bout had escalated or not. Though eavesdropping had relatively little effect on bystander-loser contest dynamics, bystanders were less prone to initiate aggression and win against losers that had escalated in the witnessed bout. Thus, bystanders appear to preferentially retain and utilize information gained about potentially dangerous opponents (winners or persistent losers). Our data lend clear support for the importance of eavesdropping in visually based aggressive signalling systems.
	Address	Department of Biology, Life Science, Room 139, University of Louisville, Louisville, KY 40292, USA. rlearl01@athena.louisville.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	0962-8452	ISBN		Medium
	Area		Expedition		Conference
	Notes	PMID:12028778			Approved	no
	Call Number	refbase @ user @			Serial	498
Permanent link to this record



	Author	Peake, T.M.; Terry, A.M.R.; McGregor, P.K.; Dabelsteen, T.
	Title	Do great tits assess rivals by combining direct experience with information gathered by eavesdropping?			Type	Journal Article
	Year	2002	Publication	Proceedings. Biological sciences / The Royal Society	Abbreviated Journal	Proc Biol Sci
	Volume	269	Issue	1503	Pages	1925-1929
	Keywords	Aggression; Animal Communication; Animals; Male; Songbirds/physiology; Territoriality; *Vocalization, Animal
	Abstract	Animals frequently use signals that travel further than the spacing between individuals. For every intended recipient of a given signal there are likely to be many other individuals that receive information. Eavesdropping on signalling interactions between other individuals provides a relatively cost-free method of assessing future opponents or mates. Male great tits (Parus major) extract relative information from such interactions between individuals unknown to them. Here, we show that male great tits can take information gathering a stage further and obtain more information about a previously unencountered intruder, by the hitherto unknown capability of combining information gathered by eavesdropping with that derived from their own direct interaction with an individual. Prior experience with an intruder (A) was achieved by subjecting a focal male to different levels of intrusion simulated using interactive playback. This intruder (A) then took part in a simulated interaction with an unknown male (B) outside the territorial boundary of the focal males. In response to subsequent intrusion by the second male (B), focal males showed low song output in response to males that had lost to a male that the subject was able to beat. Males of known high quality, or those about which information was ambiguous, elicited a high level of song output by focal males. We discuss the implications of this finding for the evolution of communication and social behaviour.
	Address	Department of Animal Behaviour, Zoological Institute, Copenhagen University, Tagensvej 16, DK 2200 Copenhagen N, Denmark. tmpeake@zi.ku.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:12350255			Approved	no
	Call Number	refbase @ user @			Serial	501
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	Author	Marinier, S.L.; Alexander, A.J.; Waring, G.H.
	Title	Flehmen behaviour in the domestic horse: Discrimination of conspecific odours			Type	Journal Article
	Year	1988	Publication	Applied Animal Behaviour Science	Abbreviated Journal	Appl. Anim. Behav. Sci.
	Volume	19	Issue	3-4	Pages	227-237
	Keywords
	Abstract	American Saddlebred horses were used to test the responses of domestic horses to the odours of conspecifics. In all cases the odours were tested in the absence of the donor animal. Thus the test animal's behavioural responses were concentrated on the olfactory stimuli, and possible interference from donor behaviour was eliminated. Stallions were significantly more responsive than mares and geldings. This was shown in both flehmen and sniffing behaviour to urine/vaginal secretions and in sniffing behaviour to faecal samples. Only stallions were used for subsequent tests. Stallions showed no significant differences in response to the odour of urine/vaginal secretions of an oestrus mare from that when she was not in season. Parameters used for analysis of data were frequency, latency and duration of flehmen as well as duration of responsiveness to samples. In testing for differences in odours between individual mares, two methods were used. The stallions differentiated between samples from individual mares. In some cases this differentiation was exhibited when the stallions were merely presented with the two samples in sequence. In other cases statistically significant differences in response to the odours were shown only by simultaneous presentation of the two samples to the test stallion. Parameters used for data analysis were frequency and duration of flehmen and duration of responsiveness.
	Address
	Corporate Author				Thesis
	Publisher		Place of Publication		Editor
	Language		Summary Language		Original Title
	Series Editor		Series Title		Abbreviated Series Title
	Series Volume		Series Issue		Edition
	ISSN		ISBN		Medium
	Area		Expedition		Conference
	Notes				Approved	no
	Call Number	refbase @ user @			Serial	507
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	Author	Scheffer, M.; van Nes, E.H.
	Title	Self-organized similarity, the evolutionary emergence of groups of similar species			Type	Journal Article
	Year	2006	Publication	Proceedings of the National Academy of Sciences of the United States of America	Abbreviated Journal	Proc. Natl. Acad. Sci. U.S.A.
	Volume	103	Issue	16	Pages	6230-6235
	Keywords	Animals; Competitive Behavior; Ecosystem; Evolution; Models, Biological
	Abstract	Ecologists have long been puzzled by the fact that there are so many similar species in nature. Here we show that self-organized clusters of look-a-likes may emerge spontaneously from coevolution of competitors. The explanation is that there are two alternative ways to survive together: being sufficiently different or being sufficiently similar. Using a model based on classical competition theory, we demonstrate a tendency for evolutionary emergence of regularly spaced lumps of similar species along a niche axis. Indeed, such lumpy patterns are commonly observed in size distributions of organisms ranging from algae, zooplankton, and beetles to birds and mammals, and could not be well explained by earlier theory. Our results suggest that these patterns may represent self-constructed niches emerging from competitive interactions. A corollary of our findings is that, whereas in species-poor communities sympatric speciation and invasion of open niches is possible, species-saturated communities may be characterized by convergent evolution and invasion by look-a-likes.
	Address	Aquatic Ecology and Water Quality Management Group, Department of Environmental Sciences, Wageningen University, P.O. Box 8080, 6700 DD, Wageningen, The Netherlands. marten.scheffer@wur.nl
	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:16585519			Approved	no
	Call Number	refbase @ user @			Serial	510
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