HFWU Home

Equine and Animal Cognition Reference Database

Home |  Show All |  Simple Search |  Advanced Search
Quick Search:
11-20 of 40 records found matching your query:
toggle visibility Search & Display Options
Select All    Deselect All << 1 2 3 4 >>
List View
 | 
Citations
 | 
Details
   print
  Records Links
Author Cameron, E.Z. doi  openurl
  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 (down) 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 Brilot, B.O.; Johnstone, R.A. doi  openurl
  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 (down) 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  
Permanent link to this record
 
 
Author Viscido, S.V.; Miller, M.; Wethey, D.S. openurl 
  Title The dilemma of the selfish herd: the search for a realistic movement rule Type Journal Article
  Year 2002 Publication Journal of theoretical biology Abbreviated Journal J. Theor. Biol.  
  Volume (down) 217 Issue 2 Pages 183-194  
  Keywords Animals; *Behavior, Animal; *Mass Behavior; Models, Biological; *Motor Activity; Predatory Behavior  
  Abstract The selfish herd hypothesis predicts that aggregations form because individuals move toward one another to minimize their own predation risk. The “dilemma of the selfish herd” is that movement rules that are easy for individuals to follow, fail to produce true aggregations, while rules that produce aggregations require individual behavior so complex that one may doubt most animals can follow them. If natural selection at the individual level is responsible for herding behavior, a solution to the dilemma must exist. Using computer simulations, we examined four different movement rules. Relative predation risk was different for all four movement rules (p<0.05). We defined three criteria for measuring the quality of a movement rule. A good movement rule should (a) be statistically likely to benefit an individual that follows it, (b) be something we can imagine most animals are capable of following, and (c) result in a centrally compact flock. The local crowded horizon rule, which allowed individuals to take the positions of many flock-mates into account, but decreased the influence of flock-mates with distance, best satisfied these criteria. The local crowded horizon rule was very sensitive to the animal's perceptive ability. Therefore, the animal's ability to detect its neighbors is an important factor in the dynamics of group formation.  
  Address Department of Biological Sciences, University of South Carolina, Columbia, SC, 29208, USA. viscido@u.washington.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 0022-5193 ISBN Medium  
  Area Expedition Conference  
  Notes PMID:12202112 Approved no  
  Call Number refbase @ user @ Serial 554  
Permanent link to this record
 
 
Author Viscido, S.V.; Miller, M.; Wethey, D.S. doi  openurl
  Title The response of a selfish herd to an attack from outside the group perimeter Type Journal Article
  Year 2001 Publication Journal of theoretical biology Abbreviated Journal J. Theor. Biol.  
  Volume (down) 208 Issue 3 Pages 315-328  
  Keywords Animals; *Behavior, Animal; *Computer Simulation; Models, Biological; *Movement; Predatory Behavior  
  Abstract According to the selfish herd hypothesis, animals can decrease predation risk by moving toward one another if the predator can appear anywhere and will attack the nearest target. Previous studies have shown that aggregations can form using simple movement rules designed to decrease each animal's Domain of Danger. However, if the predator attacks from outside the group's perimeter, these simple movement rules might not lead to aggregation. To test whether simple selfish movement rules would decrease predation risk for those situations when the predator attacks from outside the flock perimeter, we constructed a computer model that allowed flocks of 75 simulated fiddler crabs to react to one another, and to a predator attacking from 7 m away. We attacked simulated crab flocks with predators of different sizes and attack speeds, and computed relative predation risk after 120 time steps. Final trajectories showed flight toward the center of the flock, but curving away from the predator. Path curvature depended on the predator's size and approach speed. The average crab experienced a greater decrease in predation risk when the predator was small or slow moving. Regardless of the predator's size and speed, however, predation risk always decreased as long as crabs took their flock-mates into account. We conclude that, even when flight away from an external predator occurs, the selfish avoidance of danger can lead to aggregation.  
  Address Department of Biological Sciences, University of South Carolina, Columbia, SC 29208, U.S.A. viscido@u.washington.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 0022-5193 ISBN Medium  
  Area Expedition Conference  
  Notes PMID:11207093 Approved no  
  Call Number refbase @ user @ Serial 555  
Permanent link to this record
 
 
Author Flack, J.C.; de Waal, F.B.M.; Krakauer, D.C. doi  openurl
  Title Social structure, robustness, and policing cost in a cognitively sophisticated species Type Journal Article
  Year 2005 Publication The American Naturalist Abbreviated Journal Am Nat  
  Volume (down) 165 Issue 5 Pages E126-139  
  Keywords Animals; *Behavior, Animal; Cognition; Conflict (Psychology); Female; Macaca nemestrina/*physiology; Male; Models, Biological; *Social Behavior  
  Abstract Conflict management is one of the primary requirements for social complexity. Of the many forms of conflict management, one of the rarest and most interesting is third-party policing, or intervening impartially to control conflict. Third-party policing should be hard to evolve because policers personally pay a cost for intervening, while the benefits are diffused over the whole group. In this study we investigate the incidence and costs of policing in a primate society. We report quantitative evidence of non-kin policing in the nonhuman primate, the pigtailed macaque. We find that policing is effective at reducing the intensity of or terminating conflict when performed by the most powerful individuals. We define a measure, social power consensus, that predicts effective low-cost interventions by powerful individuals and ineffective, relatively costly interventions by low-power individuals. Finally, we develop a simple probabilistic model to explore whether the degree to which policing can effectively reduce the societal cost of conflict is dependent on variance in the distribution of power. Our data and simple model suggest that third-party policing effectiveness and cost are dependent on power structure and might emerge only in societies with high variance in power.  
  Address Santa Fe Institute, Santa Fe, New Mexico 87501, USA. jflack@santafe.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 1537-5323 ISBN Medium  
  Area Expedition Conference  
  Notes PMID:15795848 Approved no  
  Call Number refbase @ user @ Serial 168  
Permanent link to this record
 
 
Author Uehara, T.; Yokomizo, H.; Iwasa, Y. doi  openurl
  Title Mate-choice copying as Bayesian decision making Type Journal Article
  Year 2005 Publication The American naturalist Abbreviated Journal Am Nat  
  Volume (down) 165 Issue 3 Pages 403-410  
  Keywords Animals; *Bayes Theorem; *Choice Behavior; Female; Male; *Models, Biological; *Sexual Behavior, Animal  
  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.  
  Address Department of Biology, Faculty of Sciences, Kyushu University, Fukuoka 812-8581, Japan. uehara@bio-math.biology.kyushu-u.ac.jp  
  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:15729669 Approved no  
  Call Number Serial 1821  
Permanent link to this record
 
 
Author Dubois, F.; Giraldeau, L.-A.; Hamilton, I.M.; Grant, J.W.A.; Lefebvre, L. doi  openurl
  Title Distraction sneakers decrease the expected level of aggression within groups: a game-theoretic model Type Journal Article
  Year 2004 Publication The American Naturalist Abbreviated Journal Am Nat  
  Volume (down) 164 Issue 2 Pages E32-45  
  Keywords *Aggression; Animals; Behavior, Animal/*physiology; Columbidae/*physiology; Competitive Behavior; Cooperative Behavior; *Game Theory; Hawks/*physiology; Models, Biological  
  Abstract Hawk-dove games have been extensively used to predict the conditions under which group-living animals should defend their resources against potential usurpers. Typically, game-theoretic models on aggression consider that resource defense may entail energetic and injury costs. However, intruders may also take advantage of owners who are busy fighting to sneak access to unguarded resources, imposing thereby an additional cost on the use of the escalated hawk strategy. In this article we modify the two-strategy hawk-dove game into a three-strategy hawk-dove-sneaker game that incorporates a distraction-sneaking tactic, allowing us to explore its consequences on the expected level of aggression within groups. Our model predicts a lower proportion of hawks and hence lower frequencies of aggressive interactions within groups than do previous two-strategy hawk-dove games. The extent to which distraction sneakers decrease the frequency of aggression within groups, however, depends on whether they search only for opportunities to join resources uncovered by other group members or for both unchallenged resources and opportunities to usurp.  
  Address Departement des Sciences Biologiques, Universite du Quebec a Montreal, Case postale 8888 Succursale Centre-Ville, Montreal, Quebec H3C 3P8, Canada. frede_dubois@yahoo.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 1537-5323 ISBN Medium  
  Area Expedition Conference  
  Notes PMID:15278850 Approved no  
  Call Number Serial 2130  
Permanent link to this record
 
 
Author Dubois, F.; Giraldeau, L.-A. openurl 
  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 (down) 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  
Permanent link to this record
 
 
Author Kiltie, R.A.; Fan, J.; Laine, A.F. openurl 
  Title A wavelet-based metric for visual texture discrimination with applications in evolutionary ecology Type Journal Article
  Year 1995 Publication Mathematical Biosciences Abbreviated Journal Math Biosci  
  Volume (down) 126 Issue 1 Pages 21-39  
  Keywords Animals; Carnivora; *Ecology; Equidae; *Evolution; Humans; Mathematics; Models, Biological; Moths; *Pattern Recognition, Visual; Pigmentation  
  Abstract Much work on natural and sexual selection is concerned with the conspicuousness of visual patterns (textures) on animal and plant surfaces. Previous attempts by evolutionary biologists to quantify apparency of such textures have involved subjective estimates of conspicuousness or statistical analyses based on transect samples. We present a method based on wavelet analysis that avoids subjectivity and that uses more of the information in image textures than transects do. Like the human visual system for texture discrimination, and probably like that of other vertebrates, this method is based on localized analysis of orientation and frequency components of the patterns composing visual textures. As examples of the metric's utility, we present analyses of crypsis for tigers, zebras, and peppered moth morphs.  
  Address Department of Zoology, University of Florida, Gainesville  
  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 0025-5564 ISBN Medium  
  Area Expedition Conference  
  Notes PMID:7696817 Approved no  
  Call Number Equine Behaviour @ team @ Serial 2660  
Permanent link to this record
 
 
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 (down) 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  
Permanent link to this record
Select All    Deselect All << 1 2 3 4 >>
List View
 | 
Citations
 | 
Details
   print
toggle visibility Cite Options
Home CQL Search  |  Library Search  |  Show Record  |  Extract Citations Help