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Author Bergstrom,C. T.; Lachmann, M. openurl 
  Title Signalling among relatives. I. Is costly signalling too costly? Type Journal Article
  Year 1997 Publication Proceedings of the National Academy of Sciences of the United States of America Abbreviated Journal Proc. Natl. Acad. Sci. U.S.A.  
  Volume 352(1353) Issue (up) Pages 609-617  
  Keywords Signalling  
  Abstract ahavi's handicap principle,originally proposed as an explanation for sexual selection ofelaborate male traits, suggests that a sufficient cost to dishonest signals can outweigh the rewards of deception and allow individuals to communicate honestly. Maynard Smith (1991) and Johnstone and Grafen (1992) introduce the Sir Philip Sidney game in order to extend the handicap principle to interactions among related individuals, and to demonstrate that stable costly signalling systems can exist among relatives.

In this paper we demonstrate that despite the benefits associated with honest information transfer, the costs incurred in a stable costly signalling system may leave all participants worse off than they would be in a system with no signalling at all. In both the discrete and continuous forms of the Sir Philip Sidney game, there exist conditions under which costly signalling among relatives, while stable, is so costly that it is disadvantageous compared with no signalling at all. We determine the factors which dictate signal cost and signal benefit in a generalized version of this game, and explain how signal cost can exceed signal value. Such results raise concerns about theevolutionary pathways which could have led to the existence of signalling equilibria in nature. The paper stresses the importance of comparing signalling equilibria with other possible strategies, beforedrawing conclusions regarding the optimality of signalling.
 
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  Call Number refbase @ user @ Serial 559  
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Author Mettke-Hofmann, C.; Gwinner, E. doi  openurl
  Title Long-term memory for a life on the move Type Journal Article
  Year 2003 Publication Proceedings of the National Academy of Sciences of the United States of America Abbreviated Journal Proc. Natl. Acad. Sci. U.S.A.  
  Volume 100 Issue (up) 10 Pages 5863-5866  
  Keywords Animals; Germany; Israel; Memory/*physiology; Models, Biological; Periodicity; Songbirds/*physiology  
  Abstract Evidence is accumulating that cognitive abilities are shaped by the specific ecological conditions to which animals are exposed. Long-distance migratory birds may provide a striking example of this. Field observations have shown that, at least in some species, a substantial proportion of individuals return to the same breeding, wintering, and stopover sites in successive years. This observation suggests that migrants have evolved special cognitive abilities that enable them to accomplish these feats. Here we show that memory of a particular feeding site persisted for at least 12 months in a long-distance migrant, whereas a closely related nonmigrant could remember such a site for only 2 weeks. Thus, it seems that the migratory lifestyle has influenced the learning and memorizing capacities of migratory birds. These results build a bridge between field observations suggesting special memorization feats of migratory birds and previous neuroanatomical results from the same two species indicating an increase in relative hippocampal size from the first to the second year of life in the migrant but not in the nonmigrant.  
  Address Max Planck Research Centre for Ornithology, Department of Biological Rhythms and Behaviour, Von-der-Tann-Strasse 7, 82346 Andechs, Germany. mettke-hofmann@erl.ornithol.mpg.de  
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  ISSN 0027-8424 ISBN Medium  
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  Notes PMID:12719527 Approved no  
  Call Number refbase @ user @ Serial 511  
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Author Reiss, D.; Marino, L. doi  openurl
  Title Mirror self-recognition in the bottlenose dolphin: a case of cognitive convergence 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 (up) 10 Pages 5937-5942  
  Keywords Animals; *Cognition; Dolphins/*physiology; *Visual Perception  
  Abstract The ability to recognize oneself in a mirror is an exceedingly rare capacity in the animal kingdom. To date, only humans and great apes have shown convincing evidence of mirror self-recognition. Two dolphins were exposed to reflective surfaces, and both demonstrated responses consistent with the use of the mirror to investigate marked parts of the body. This ability to use a mirror to inspect parts of the body is a striking example of evolutionary convergence with great apes and humans.  
  Address Osborn Laboratories of Marine Sciences, New York Aquarium, Wildlife Conservation Society, Brooklyn, NY 11224, USA. dlr28@columbia.edu  
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  Notes PMID:11331768 Approved no  
  Call Number Equine Behaviour @ team @ Serial 2822  
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Author Ballew, R.M.; Sabelko, J.; Gruebele, M. openurl 
  Title Direct observation of fast protein folding: the initial collapse of apomyoglobin Type Journal Article
  Year 1996 Publication Proceedings of the National Academy of Sciences of the United States of America Abbreviated Journal Proc. Natl. Acad. Sci. U.S.A.  
  Volume 93 Issue (up) 12 Pages 5759-5764  
  Keywords Animals; Apoproteins/*chemistry; Circular Dichroism; Horses; Kinetics; Muscle, Skeletal/chemistry; Myoglobin/*chemistry; *Protein Folding; Spectrometry, Fluorescence; Spectrophotometry, Infrared; Temperature  
  Abstract The rapid refolding dynamics of apomyoglobin are followed by a new temperature-jump fluorescence technique on a 15-ns to 0.5-ms time scale in vitro. The apparatus measures the protein-folding history in a single sweep in standard aqueous buffers. The earliest steps during folding to a compact state are observed and are complete in under 20 micros. Experiments on mutants and consideration of steady-state CD and fluorescence spectra indicate that the observed microsecond phase monitors assembly of an A x (H x G) helix subunit. Measurements at different viscosities indicate diffusive behavior even at low viscosities, in agreement with motions of a solvent-exposed protein during the initial collapse.  
  Address School of Chemical Sciences and Beckman Institute for Advanced Science and Technology, University of Illinois, Urbana, 61801, USA  
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  Notes PMID:8650166 Approved no  
  Call Number Equine Behaviour @ team @ Serial 3798  
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Author Biegler, R.; McGregor, A.; Krebs, J.R.; Healy, S.D. url  doi
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  Title A larger hippocampus is associated with longer-lasting spatial memory 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 (up) 12 Pages 6941-6944  
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  Abstract Volumetric studies in a range of animals (London taxi-drivers, polygynous male voles, nest-parasitic female cowbirds, and a number of food-storing birds) have shown that the size of the hippocampus, a brain region essential to learning and memory, is correlated with tasks involving an extra demand for spatial learning and memory. In this paper, we report the quantitative advantage that food storers gain from such an enlargement. Coal tits () a food-storing species, performed better than great tits (), a nonstoring species, on a task that assessed memory persistence but not on a task that assessed memory resolution or on one that tested memory capacity. These results show that the advantage to the food-storing species associated with an enlarged hippocampus is one of memory persistence.  
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  Notes 10.1073/pnas.121034798 Approved no  
  Call Number Equine Behaviour @ team @ Serial 4743  
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Author Dusek, J.A.; Eichenbaum, H. openurl 
  Title The hippocampus and memory for orderly stimulus relations Type Journal Article
  Year 1997 Publication Proceedings of the National Academy of Sciences of the United States of America Abbreviated Journal Proc. Natl. Acad. Sci. U.S.A.  
  Volume 94 Issue (up) 13 Pages 7109-7114  
  Keywords Animals; Attention; Discrimination (Psychology)/physiology; Hippocampus/anatomy & histology/*physiology; Male; Memory/*physiology; Rats  
  Abstract Human declarative memory involves a systematic organization of information that supports generalizations and inferences from acquired knowledge. This kind of memory depends on the hippocampal region in humans, but the extent to which animals also have declarative memory, and whether inferential expression of memory depends on the hippocampus in animals, remains a major challenge in cognitive neuroscience. To examine these issues, we used a test of transitive inference pioneered by Piaget to assess capacities for systematic organization of knowledge and logical inference in children. In our adaptation of the test, rats were trained on a set of four overlapping odor discrimination problems that could be encoded either separately or as a single representation of orderly relations among the odor stimuli. Normal rats learned the problems and demonstrated the relational memory organization through appropriate transitive inferences about items not presented together during training. By contrast, after disconnection of the hippocampus from either its cortical or subcortical pathway, rats succeeded in acquiring the separate discrimination problems but did not demonstrate transitive inference, indicating that they had failed to develop or could not inferentially express the orderly organization of the stimulus elements. These findings strongly support the view that the hippocampus mediates a general declarative memory capacity in animals, as it does in humans.  
  Address Department of Psychology, Boston University, 64 Cummington Street, Boston, MA 02215, USA  
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  Notes PMID:9192700 Approved no  
  Call Number refbase @ user @ Serial 607  
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Author Amé, J.-M.; Halloy, J.; Rivault, C.; Detrain, C.; Deneubourg, J.L. doi  openurl
  Title Collegial decision making based on social amplification leads to optimal group formation 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 (up) 15 Pages 5835-5840  
  Keywords Animals; Blattellidae/*physiology; Choice Behavior; Decision Making; Leadership; *Social Behavior  
  Abstract Group-living animals are often faced with choosing between one or more alternative resource sites. A central question in such collective decision making includes determining which individuals induce the decision and when. This experimental and theoretical study of shelter selection by cockroach groups demonstrates that choices can emerge through nonlinear interaction dynamics between equal individuals without perfect knowledge or leadership. We identify a simple mechanism whereby a decision is taken on the move with limited information and signaling and without comparison of available opportunities. This mechanism leads to optimal mean benefit for group individuals. Our model points to a generic self-organized collective decision-making process independent of animal species.  
  Address Service d'Ecologie Sociale CP231, Universite Libre de Bruxelles, Avenue F. D. Roosevelt 50, B-1050 Brussels, Belgium  
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  Notes PMID:16581903 Approved no  
  Call Number Equine Behaviour @ team @ Serial 2042  
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Author Sol, D.; Duncan, R.P.; Blackburn, T.M.; Cassey, P.; Lefebvre, L. url  doi
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  Title Big brains, enhanced cognition, and response of birds to novel environments Type Journal Article
  Year 2005 Publication Proceedings of the National Academy of Sciences of the United States of America Abbreviated Journal Proc. Natl. Acad. Sci. U.S.A.  
  Volume 102 Issue (up) 15 Pages 5460-5465  
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  Abstract The widely held hypothesis that enlarged brains have evolved as an adaptation to cope with novel or altered environmental conditions lacks firm empirical support. Here, we test this hypothesis for a major animal group (birds) by examining whether large-brained species show higher survival than small-brained species when introduced to nonnative locations. Using a global database documenting the outcome of >600 introduction events, we confirm that avian species with larger brains, relative to their body mass, tend to be more successful at establishing themselves in novel environments. Moreover, we provide evidence that larger brains help birds respond to novel conditions by enhancing their innovation propensity rather than indirectly through noncognitive mechanisms. These findings provide strong evidence for the hypothesis that enlarged brains function, and hence may have evolved, to deal with changes in the environment.  
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  Notes 10.1073/pnas.0408145102 Approved no  
  Call Number Equine Behaviour @ team @ Serial 4739  
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Author Johnstone, R.A. doi  openurl
  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 (up) 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  
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  Notes PMID:11459936 Approved no  
  Call Number refbase @ user @ Serial 497  
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Author Scheffer, M.; van Nes, E.H. doi  openurl
  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 (up) 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  
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  Notes PMID:16585519 Approved no  
  Call Number refbase @ user @ Serial 510  
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