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Author |
Cameron, E.Z. |
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Title |
Facultative adjustment of mammalian sex ratios in support of the Trivers-Willard hypothesis: evidence for a mechanism |
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Journal Article |
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Year |
2004 |
Publication |
Proceedings. Biological sciences / The Royal Society |
Abbreviated Journal |
Proc Biol Sci |
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Volume |
271 |
Issue |
1549 |
Pages |
1723-1728 |
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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 |
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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. |
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Mammal Research Institute, Department of Zoology and Entomology, University of Pretoria, Pretoria 0002, South Africa. ezcameron@zoology.up.ac.za |
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0962-8452 |
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PMID:15306293 |
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refbase @ user @ |
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413 |
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Author |
Bell, A.M. |
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Title |
Evolutionary biology: animal personalities |
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2007 |
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Nature |
Abbreviated Journal |
Nature |
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Volume |
447 |
Issue |
7144 |
Pages |
539-540 |
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Keywords |
Aggression/physiology/psychology; Animals; Behavior, Animal/*physiology; *Evolution; Humans; *Models, Biological; Personality/genetics/*physiology; Reproduction/genetics/physiology; Risk-Taking; Selection (Genetics) |
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1476-4687 |
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PMID:17538607 |
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Equine Behaviour @ team @ |
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4099 |
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Author |
Johnson, D.D.P.; Stopka, P.; Knights, S. |
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Title |
Sociology: The puzzle of human cooperation |
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Journal Article |
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Year |
2003 |
Publication |
Nature |
Abbreviated Journal |
Nature |
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Volume |
421 |
Issue |
6926 |
Pages |
911-2; discussion 912 |
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Keywords |
Altruism; *Cooperative Behavior; Evolution; Humans; *Models, Biological; Punishment; Reward; Risk |
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Olin Institute for Strategic Studies, Harvard University, Cambridge, Massachusetts 02138, USA. dominic@post.harvard.edu |
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0028-0836 |
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PMID:12606989 |
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refbase @ user @ |
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467 |
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Tobin, T.; Combie, J.D. |
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Performance testing in horses: a review of the role of simple behavioral models in the design of performance experiments |
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Journal Article |
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Year |
1982 |
Publication |
Journal of Veterinary Pharmacology and Therapeutics |
Abbreviated Journal |
J Vet Pharmacol Ther |
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Volume |
5 |
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2 |
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105-118 |
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Analgesics, Opioid/pharmacology; Animals; Apomorphine/pharmacology; Behavior, Animal/*drug effects; Dose-Response Relationship, Drug; Fentanyl/pharmacology; Horses/*physiology; Methylphenidate/pharmacology; *Models, Biological; Motor Activity/drug effects |
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0140-7783 |
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PMID:6125601 |
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refbase @ user @ |
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1957 |
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Author |
Uehara, T.; Yokomizo, H.; Iwasa, Y. |
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Title |
Mate-choice copying as Bayesian decision making |
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Journal Article |
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Year |
2005 |
Publication |
The American naturalist |
Abbreviated Journal |
Am Nat |
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Volume |
165 |
Issue |
3 |
Pages |
403-410 |
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Keywords |
Animals; *Bayes Theorem; *Choice Behavior; Female; Male; *Models, Biological; *Sexual Behavior, Animal |
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Abstract |
Mate-choice copying by females has been reported in fishes (e.g., guppies) and lekking birds. Presumably, females assess males' quality using both information from direct observation of males and information acquired by observing other females' choices. Here, we study mathematically the conditions under which mate-choice copying is advantageous on the basis of Bayesian decision theory. A female may observe the mate choice of another female, called the model female, who has performed an optimal choice based on her own judgment. The conditions required for the focal female to choose the same mate as that chosen by the model female should depend on the male's appearance to her, the reliability of her own judgment of male quality, and the reliability of the model females. When three or more females are involved, the optimal mate choice critically depends on whether multiple model females make decisions independently or they themselves copy the choices of others. If two equally reliable females choose different males, the choice of the second female, made knowing the choice of the first, should have a stronger effect on the choice of the third (focal) female. This “last-choice precedence” should be tested experimentally. |
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Address |
Department of Biology, Faculty of Sciences, Kyushu University, Fukuoka 812-8581, Japan. uehara@bio-math.biology.kyushu-u.ac.jp |
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1537-5323 |
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PMID:15729669 |
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1821 |
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Author |
Kaplan, A.I.; Borodovskii, M.I. |
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Title |
[Alternative animal behavior: a model and its statistical characteristics] |
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Journal Article |
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Year |
1989 |
Publication |
Nauchnye Doklady Vysshei Shkoly. Biologicheskie Nauki |
Abbreviated Journal |
Nauchnye Doki Vyss Shkoly Biol Nauki |
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3 |
Pages |
29-32 |
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Keywords |
Animals; *Behavior, Animal; Cognition; Male; Mathematics; *Models, Biological; *Models, Statistical; Rats; Reinforcement (Psychology) |
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Abstract |
The rats' alternative behaviour in T-maze at simultaneous two-sided food refreshment in 13 trials a day during 6 days has been studied. It has been found that in the first testing days the indexes of alternative behaviour of animals correspond to the characteristics of the random alternation. However, on the 5-6th day of testing in the overwhelming majority of rats the true deviation of alternation index above or below than the theoretical values has been revealed. A question on the existence of two strategies of cognitive behaviour alteration and perseveration in rat population is under discussion. |
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Russian |
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Al'ternativnoe povedenie zhivotnykh: model' i statisticheskie kharakteristiki |
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0470-4606 |
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PMID:2742929 |
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Call Number |
Equine Behaviour @ team @ |
Serial |
2799 |
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Author |
Scheffer, M.; van Nes, E.H. |
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Title |
Self-organized similarity, the evolutionary emergence of groups of similar species |
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Journal Article |
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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. |
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Volume |
103 |
Issue |
16 |
Pages |
6230-6235 |
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Keywords |
Animals; *Competitive Behavior; *Ecosystem; *Evolution; *Models, Biological |
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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. |
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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 |
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0027-8424 |
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PMID:16585519 |
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Call Number |
refbase @ user @ |
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510 |
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Author |
Rands, S.A.; Cowlishaw, G.; Pettifor, R.A.; Rowcliffe, J.M.; Johnstone, R.A. |
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Title |
Spontaneous emergence of leaders and followers in foraging pairs |
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Journal Article |
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Year |
2003 |
Publication |
Nature |
Abbreviated Journal |
Nature |
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Volume |
423 |
Issue |
6938 |
Pages |
432-434 |
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Animals; *Energy Metabolism; Food; *Food Chain; *Models, Biological; Motor Activity; *Social Behavior; Time Factors |
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Abstract |
Animals that forage socially often stand to gain from coordination of their behaviour. Yet it is not known how group members reach a consensus on the timing of foraging bouts. Here we demonstrate a simple process by which this may occur. We develop a state-dependent, dynamic game model of foraging by a pair of animals, in which each individual chooses between resting or foraging during a series of consecutive periods, so as to maximize its own individual chances of survival. We find that, if there is an advantage to foraging together, the equilibrium behaviour of both individuals becomes highly synchronized. As a result of this synchronization, differences in the energetic reserves of the two players spontaneously develop, leading them to adopt different behavioural roles. The individual with lower reserves emerges as the 'pace-maker' who determines when the pair should forage, providing a straightforward resolution to the problem of group coordination. Moreover, the strategy that gives rise to this behaviour can be implemented by a simple 'rule of thumb' that requires no detailed knowledge of the state of other individuals. |
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Department of Zoology, University of Cambridge, Downing Street, Cambridge CB2 3EJ, UK. s.rands@zoo.cam.ac.uk |
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0028-0836 |
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PMID:12761547 |
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Call Number |
Equine Behaviour @ team @ |
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5138 |
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Author |
Rands, S.A.; Cowlishaw, G.; Pettifor, R.A.; Rowcliffe, J.M.; Johnstone, R.A. |
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Title |
The emergence of leaders and followers in foraging pairs when the qualities of individuals differ |
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Journal Article |
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Year |
2008 |
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BMC Evolutionary Biology |
Abbreviated Journal |
BMC Evol Biol |
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8 |
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51 |
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Keywords |
Animals; *Feeding Behavior; *Food Chain; *Models, Biological; *Social Dominance |
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Abstract |
BACKGROUND: Foraging in groups offers animals a number of advantages, such as increasing their likelihood of finding food or detecting and avoiding predators. In order for a group to remain together, there has to be some degree of coordination of behaviour and movement between its members (which may in some cases be initiated by a decision-making leader, and in other cases may emerge as an underlying property of the group). For example, behavioural synchronisation is a phenomenon where animals within a group initiate and then continue to conduct identical behaviours, and has been characterised for a wide range of species. We examine how a pair of animals should behave using a state-dependent approach, and ask what conditions are likely to lead to behavioural synchronisation occurring, and whether one of the individuals is more likely to act as a leader. RESULTS: The model we describe considers how the energetic gain, metabolic requirements and predation risks faced by the individuals affect measures of their energetic state and behaviour (such as the degree of behavioural synchronisation seen within the pair, and the value to an individual of knowing the energetic state of its colleague). We explore how predictable changes in these measures are in response to changes in physiological requirements and predation risk. We also consider how these measures should change when the members of the pair are not identical in their metabolic requirements or their susceptibility to predation. We find that many of the changes seen in these measures are complex, especially when asymmetries exist between the members of the pair. CONCLUSION: Analyses are presented that demonstrate that, although these general patterns are robust, care needs to be taken when considering the effects of individual differences, as the relationship between individual differences and the resulting qualitative changes in behaviour may be complex. We discuss how these results are related to experimental observations, and how the model and its predictions could be extended. |
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Department of Zoology, University of Cambridge, Downing Street, Cambridge CB2 3EJ, UK. sean.rands@bristol.ac.uk |
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1471-2148 |
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PMID:18282297 |
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Equine Behaviour @ team @ |
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5126 |
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Author |
Hamilton, W.D. |
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Title |
Geometry for the selfish herd |
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Journal Article |
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Year |
1971 |
Publication |
Journal of theoretical biology |
Abbreviated Journal |
J. Theor. Biol. |
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31 |
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2 |
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295-311 |
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Animals; Anura; *Behavior, Animal; Breeding; Communication; Evolution; Fear; Metallurgy; *Models, Biological; Probability; Snakes; *Spatial Behavior |
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This paper presents an antithesis to the view that gregarious behaviour is evolved through benefits to the population or species. Following Galton (1871) and Williams (1964) gregarious behaviour is considered as a form of cover-seeking in which each animal tries to reduce its chance of being caught by a predator.
It is easy to see how pruning of marginal individuals can maintain centripetal instincts in already gregarious species; some evidence that marginal pruning actually occurs is summarized. Besides this, simply defined models are used to show that even in non-gregarious species selection is likely to favour individuals who stay close to others.
Although not universal or unipotent, cover-seeking is a widespread and important element in animal aggregation, as the literature shows. Neglect of the idea has probably followed from a general disbelief that evolution can be dysgenic for a species. Nevertheless, selection theory provides no support for such disbelief in the case of species with outbreeding or unsubdivided populations.
The model for two dimensions involves a complex problem in geometrical probability which has relevance also in metallurgy and communication science. Some empirical data on this, gathered from random number plots, is presented as of possible heuristic value. |
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0022-5193 |
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PMID:5104951 |
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refbase @ user @ |
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771 |
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